1
|
Macalinao MLM, Fornace KM, Reyes RA, Hall T, Bareng APN, Adams JH, Huon C, Chitnis CE, Luchavez JS, Tetteh KK, Yui K, Hafalla JCR, Espino FEJ, Drakeley CJ. Analytical approaches for antimalarial antibody responses to confirm historical and recent malaria transmission: an example from the Philippines. THE LANCET REGIONAL HEALTH. WESTERN PACIFIC 2023; 37:100792. [PMID: 37693871 PMCID: PMC10485684 DOI: 10.1016/j.lanwpc.2023.100792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 03/20/2023] [Accepted: 04/28/2023] [Indexed: 09/12/2023]
Abstract
Background Assessing the status of malaria transmission in endemic areas becomes increasingly challenging as countries approach elimination. Serology can provide robust estimates of malaria transmission intensities, and multiplex serological assays allow for simultaneous assessment of markers of recent and historical malaria exposure. Methods Here, we evaluated different statistical and machine learning methods for analyzing multiplex malaria-specific antibody response data to classify recent and historical exposure to Plasmodium falciparum and Plasmodium vivax. To assess these methods, we utilized samples from a health-facility based survey (n = 9132) in the Philippines, where we quantified antibody responses against 8 P. falciparum and 6 P. vivax-specific antigens from 3 sites with varying transmission intensity. Findings Measurements of antibody responses and seroprevalence were consistent with the 3 sites' known endemicity status. Among the models tested, a machine learning (ML) approach (Random Forest model) using 4 serological markers (PfGLURP R2, Etramp5.Ag1, GEXP18, and PfMSP119) gave better predictions for P. falciparum recent infection in Palawan (AUC: 0.9591, CI 0.9497-0.9684) than individual antigen seropositivity. Although the ML approach did not improve P. vivax infection predictions, ML classifications confirmed the absence of recent exposure to P. falciparum and P. vivax in both Occidental Mindoro and Bataan. For predicting historical P. falciparum and P. vivax transmission, seroprevalence and seroconversion rates based on cumulative exposure markers AMA1 and MSP119 showed reliable trends in the 3 sites. Interpretation Our study emphasizes the utility of serological markers in predicting recent and historical exposure in a sub-national elimination setting, and also highlights the potential use of machine learning models using multiplex antibody responses to improve assessment of the malaria transmission status of countries aiming for elimination. This work also provides baseline antibody data for monitoring risk in malaria-endemic areas in the Philippines. Funding Newton Fund, Philippine Council for Health Research and Development, UK Medical Research Council.
Collapse
Affiliation(s)
- Maria Lourdes M. Macalinao
- Department of Parasitology and National Reference Laboratory for Malaria and Other Parasites, Research Institute for Tropical Medicine, Department of Health, Muntinlupa City, Philippines
- Faculty of Infectious and Tropical Diseases, Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
| | - Kimberly M. Fornace
- Faculty of Infectious and Tropical Diseases, Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
- Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Ralph A. Reyes
- Department of Parasitology and National Reference Laboratory for Malaria and Other Parasites, Research Institute for Tropical Medicine, Department of Health, Muntinlupa City, Philippines
| | - Tom Hall
- Faculty of Infectious and Tropical Diseases, Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Alison Paolo N. Bareng
- Department of Parasitology and National Reference Laboratory for Malaria and Other Parasites, Research Institute for Tropical Medicine, Department of Health, Muntinlupa City, Philippines
| | | | - Christèle Huon
- Malaria Parasite Biology and Vaccines Unit, Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France
| | - Chetan E. Chitnis
- Malaria Parasite Biology and Vaccines Unit, Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France
| | - Jennifer S. Luchavez
- Department of Parasitology and National Reference Laboratory for Malaria and Other Parasites, Research Institute for Tropical Medicine, Department of Health, Muntinlupa City, Philippines
| | - Kevin K.A. Tetteh
- Faculty of Infectious and Tropical Diseases, Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Katsuyuki Yui
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
- Shionogi Global Infectious Diseases Division, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Julius Clemence R. Hafalla
- Faculty of Infectious and Tropical Diseases, Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Fe Esperanza J. Espino
- Department of Parasitology and National Reference Laboratory for Malaria and Other Parasites, Research Institute for Tropical Medicine, Department of Health, Muntinlupa City, Philippines
| | - Chris J. Drakeley
- Faculty of Infectious and Tropical Diseases, Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| |
Collapse
|
2
|
Okek EJ, Ocan M, Obondo SJ, Kiyimba A, Arinaitwe E, Nankabirwa J, Ssewanyana I, Kamya MR. Effects of anti-malarial prophylaxes on maternal transfer of Immunoglobulin-G (IgG) and association to immunity against Plasmodium falciparum infections among children in a Ugandan birth cohort. PLoS One 2023; 18:e0277789. [PMID: 36812236 PMCID: PMC9946240 DOI: 10.1371/journal.pone.0277789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 10/10/2022] [Indexed: 02/24/2023] Open
Abstract
BACKGROUND The in-utero transfer of malaria specific IgG to the fetus in Plasmodium falciparum infected pregnant women potentially plays a role in provision of immune protection against malaria in the first birth year. However, the effect of Intermittent Prophylactic Treatment in Pregnancy (IPTp) and placental malaria on the extent of in-utero antibody transfer in malaria endemic regions like Uganda remain unknown. The aim of this study was thus to establish the effect of IPTp on in-utero transfer of malaria specific IgG to the fetus and the associated immune protection against malaria in the first birth year of children born to mothers who had P. falciparum infection during pregnancy in Uganda. METHODS We screened a total of 637 cord blood samples from a double blinded randomized clinical trial on Sulfadoxine-Pyrimethamine (SP) and Dihydroartemisinin-Piperaquine (DP) IPTp in a Ugandan birth cohort; study conducted from Busia, Eastern Uganda. Luminex assay was used to measure the cord levels of IgG sub-types (IgG1, IgG2, IgG3 and IgG4) against 15 different P. falciparum specific antigens, with tetanus toxoid (t.t) as a control antigen. Man-Whitney U test (non-parametric) in STATA (ver15) was used in statistical analysis of the samples. In addition, Multivariate cox regression analysis was used to determine the effect of maternal transfer of IgG on the incidence of malaria in the first birth year of children under study. RESULTS Mothers on SP expressed higher levels of cord IgG4 against erythrocyte binding antigens (EBA140, EBA175 and EBA181) (p<0.05). Placental malaria did not affect cord levels of IgG sub-types against selected P. falciparum specific antigens (p>0.05). Children who expressed higher levels (75th percentile) of total IgG against the six key P. falciparum antigens (Pf SEA, Rh4.2, AMA1, GLURP, Etramp5Ag1 and EBA 175) had higher risk of malaria in the first birth year; AHRs: 1.092, 95% CI: 1.02-1.17 (Rh4.2); 1.32, 95% CI: 1.00-1.74 (PfSEA); 1.21, 95%CI: 0.97-1.52 (Etramp5Ag1); 1.25, 95%CI: 0.98-1.60 (AMA1); 1.83, 95%CI: 1.15-2.93 (GLURP) (GLURP), and 1.35,; 95%CI: 1.03-1.78 (EBA175). Children born to mothers categorized as poorest had the highest risk of malaria infections in the first birth year (AHR: 1.79, 95% CI: 1.31-2.4). Children born to mothers who had malaria infections during gestation had higher risk of getting malaria in the first birth year (AHR 1.30; 95%CI: 0.97-1.7). CONCLUSION Malaria prophylaxis in pregnant mothers using either DP or SP does not affect expression of antibodies against P. falciparum specific antigens in the cord blood. Poverty and malaria infections during pregnancy are key risk factors of malaria infections in the first birth year of growth of children. Antibodies against P. falciparum specific antigens does not protect against parasitemia and malaria infections in the first birth year of children born in malaria endemic areas.
Collapse
Affiliation(s)
- Erick Jacob Okek
- Department of Immunology and Molecular Biology, College of Health Sciences, Makerere University, Kampala, Uganda
- Department of Medicine, Malaria Research Training Program, College of Health Sciences, Makerere University, Kampala, Uganda
- * E-mail:
| | - Moses Ocan
- Department of Medicine, Malaria Research Training Program, College of Health Sciences, Makerere University, Kampala, Uganda
- Department of Pharmacology & Therapeutics, College of Health Sciences, Makerere University, Kampala, Uganda
| | - Sande James Obondo
- Department of Immunology and Molecular Biology, College of Health Sciences, Makerere University, Kampala, Uganda
| | - Anthony Kiyimba
- San Francisco Infectious Disease Research Collaboration, Makerere University-University of California, Kampala, Uganda
| | - Emmanuel Arinaitwe
- Department of Medicine, Malaria Research Training Program, College of Health Sciences, Makerere University, Kampala, Uganda
- San Francisco Infectious Disease Research Collaboration, Makerere University-University of California, Kampala, Uganda
| | - Joaniter Nankabirwa
- Department of Medicine, Malaria Research Training Program, College of Health Sciences, Makerere University, Kampala, Uganda
- San Francisco Infectious Disease Research Collaboration, Makerere University-University of California, Kampala, Uganda
| | - Isaac Ssewanyana
- San Francisco Infectious Disease Research Collaboration, Makerere University-University of California, Kampala, Uganda
- Central Public Health Laboratories, Ministry of Health, Kampala, Uganda
| | - Moses Robert Kamya
- Department of Medicine, Malaria Research Training Program, College of Health Sciences, Makerere University, Kampala, Uganda
- San Francisco Infectious Disease Research Collaboration, Makerere University-University of California, Kampala, Uganda
| |
Collapse
|
3
|
de Jong RM, Alkema M, Oulton T, Dumont E, Teelen K, Nakajima R, de Assis RR, Press KWD, Ngotho P, Tetteh KK, Felgner P, Marti M, Collins KA, Drakeley C, Bousema T, Stone WJ. The acquisition of humoral immune responses targeting Plasmodium falciparum sexual stages in controlled human malaria infections. Front Immunol 2022; 13:930956. [PMID: 35924245 PMCID: PMC9339717 DOI: 10.3389/fimmu.2022.930956] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 06/28/2022] [Indexed: 11/13/2022] Open
Abstract
Individuals infected with P. falciparum develop antibody responses to intra-erythrocytic gametocyte proteins and exported gametocyte proteins present on the surface of infected erythrocytes. However, there is currently limited knowledge on the immunogenicity of gametocyte antigens and the specificity of gametocyte-induced antibody responses. In this study, we assessed antibody responses in participants of two controlled human malaria infection (CHMI) studies by ELISA, multiplexed bead-based antibody assays and protein microarray. By comparing antibody responses in participants with and without gametocyte exposure, we aimed to disentangle the antibody response induced by asexual and sexual stage parasites. We showed that after a single malaria infection, a significant anti-sexual stage humoral response is induced in malaria-naïve individuals, even after exposure to relatively low gametocyte densities (up to ~1,600 gametocytes/mL). In contrast to antibody responses to well-characterised asexual blood stage antigens that were detectable by day 21 after infection, responses to sexual stage antigens (including transmission blocking vaccine candidates Pfs48/45 and Pfs230) were only apparent at 51 days after infection. We found antigens previously associated with early gametocyte or anti-gamete immunity were highly represented among responses linked with gametocyte exposure. Our data provide detailed insights on the induction and kinetics of antibody responses to gametocytes and identify novel antigens that elicit antibody responses exclusively in individuals with gametocyte exposure. Our findings provide target identification for serological assays for surveillance of the malaria infectious reservoir, and support vaccine development by describing the antibody response to leading vaccine antigens after primary infection.
Collapse
Affiliation(s)
- Roos M. de Jong
- Department of Medical Microbiology and Radboud Centre of Infectious Diseases, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Manon Alkema
- Department of Medical Microbiology and Radboud Centre of Infectious Diseases, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Tate Oulton
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Elin Dumont
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Karina Teelen
- Department of Medical Microbiology and Radboud Centre of Infectious Diseases, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Rie Nakajima
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, United States
| | - Rafael Ramiro de Assis
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, United States
| | | | - Priscilla Ngotho
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Kevin K.A. Tetteh
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Phil Felgner
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, United States
| | - Matthias Marti
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Katharine A. Collins
- Department of Medical Microbiology and Radboud Centre of Infectious Diseases, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Teun Bousema
- Department of Medical Microbiology and Radboud Centre of Infectious Diseases, Radboud University Medical Centre, Nijmegen, Netherlands,Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Will J.R. Stone
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom,*Correspondence: Will J.R. Stone,
| |
Collapse
|
4
|
Khan SN, Ali R, Khan S, Rooman M, Norin S, Zareen S, Ali I, Ayaz S. Genetic Diversity of Polymorphic Marker Merozoite Surface Protein 1 ( Msp-1) and 2 ( Msp-2) Genes of Plasmodium falciparum Isolates From Malaria Endemic Region of Pakistan. Front Genet 2021; 12:751552. [PMID: 34868223 PMCID: PMC8635745 DOI: 10.3389/fgene.2021.751552] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Accepted: 10/04/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Understanding the genetic diversity of Plasmodium species through polymorphic studies can assist in designing more effective control strategies of malaria like new drug formulation and development of a vaccine. Pakistan is moderate endemic for Plasmodium falciparum, but little is known about the genetic diversity of this parasite. This study aimed to investigate the molecular diversity of P. falciparum based on msp-1 and msp-2 genes in the malaria-endemic regions of Khyber Pakhtunkhwa, Pakistan. Methods: A total of 199/723 blood samples, tested positive by microscopy for falciparum malaria, were collected from four districts (Dera Ismail Khan, Karak, Mardan, and Peshawar) of Khyber Pakhtunkhwa. Nested PCR amplification technique was employed to target block 2 of msp-1 and the central domain of msp-2 genes, including their respective allelic families K1, MAD20, RO33, FC27, and 3D7/IC, and to detect the extent of genetic diversity of P. falciparum clinical isolates. Results: Among the 199 microscopy-positive P. falciparum samples, a total of 192 were confirmed using PCR. Ninety-seven amplicons were observed for msp-1 and 95 for msp-2. A total of 33 genotypes, 17 for msp-1 (eight K1, six MAD20, and three RO33) and 16 for msp-2 (nine FC27 and seven 3D7/IC), were identified. The specific allelic frequency of the K1 family was higher (44.3%) than that of MAD20 (33.0%) and RO33 (23.0%) for msp-1, while the FC27 allelic family was dominant (60.0%) compared with 3D7/IC (40.0%) for msp-2. No polyclonal infection was observed in msp-1 and msp-2. The expected heterozygosity was 0.98 and 0.97 for msp-1 and msp-2, respectively. Conclusion: It was concluded that the P. falciparum populations are highly polymorphic, and diverse allelic variants of msp-1 and msp-2 are present in Khyber Pakhtunkhwa, Pakistan.
Collapse
Affiliation(s)
- Shahid Niaz Khan
- Department of Zoology, Faculty of Biological Sciences, Kohat University of Science and Technology, Kohat, Pakistan
| | - Rehman Ali
- Department of Zoology, Faculty of Biological Sciences, Kohat University of Science and Technology, Kohat, Pakistan
| | - Sanaullah Khan
- Department of Zoology, University of Peshawar, Peshawar, Pakistan
| | - Muhammad Rooman
- Department of Zoology, Hazara University, Mansehra, Pakistan
| | - Sadia Norin
- Department of Zoology, Faculty of Biological Sciences, Kohat University of Science and Technology, Kohat, Pakistan
| | - Shehzad Zareen
- Department of Zoology, Faculty of Biological Sciences, Kohat University of Science and Technology, Kohat, Pakistan
| | - Ijaz Ali
- Department of Biosciences, COMSATS University Islamabad, Islamabad, Pakistan
| | - Sultan Ayaz
- College of Veterinary Sciences and Animal Husbandry, Abdul Wali Khan University Garden Campus Mardan, Mardan, Pakistan
| |
Collapse
|
5
|
Barry A, Bradley J, Stone W, Guelbeogo MW, Lanke K, Ouedraogo A, Soulama I, Nébié I, Serme SS, Grignard L, Patterson C, Wu L, Briggs JJ, Janson O, Awandu SS, Ouedraogo M, Tarama CW, Kargougou D, Zongo S, Sirima SB, Marti M, Drakeley C, Tiono AB, Bousema T. Higher gametocyte production and mosquito infectivity in chronic compared to incident Plasmodium falciparum infections. Nat Commun 2021; 12:2443. [PMID: 33903595 PMCID: PMC8076179 DOI: 10.1038/s41467-021-22573-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 03/09/2021] [Indexed: 11/09/2022] Open
Abstract
Plasmodium falciparum gametocyte kinetics and infectivity may differ between chronic and incident infections. In the current study, we assess parasite kinetics and infectivity to mosquitoes among children (aged 5-10 years) from Burkina Faso with (a) incident infections following parasite clearance (n = 48) and (b) chronic asymptomatic infections (n = 60). In the incident infection cohort, 92% (44/48) of children develop symptoms within 35 days, compared to 23% (14/60) in the chronic cohort. All individuals with chronic infection carried gametocytes or developed them during follow-up, whereas only 35% (17/48) in the incident cohort produce gametocytes before becoming symptomatic and receiving treatment. Parasite multiplication rate (PMR) and the relative abundance of ap2-g and gexp-5 transcripts are positively associated with gametocyte production. Antibody responses are higher and PMR lower in chronic infections. The presence of symptoms and sexual stage immune responses are associated with reductions in gametocyte infectivity to mosquitoes. We observe that most incident infections require treatment before the density of mature gametocytes is sufficient to infect mosquitoes. In contrast, chronic, asymptomatic infections represent a significant source of mosquito infections. Our observations support the notion that malaria transmission reduction may be expedited by enhanced case management, involving both symptom-screening and infection detection.
Collapse
Affiliation(s)
- Aissata Barry
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
- Radboud Institute for Health Sciences and Radboud Center for Infectious Diseases, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - John Bradley
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | - Will Stone
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Moussa W Guelbeogo
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Kjerstin Lanke
- Radboud Institute for Health Sciences and Radboud Center for Infectious Diseases, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Alphonse Ouedraogo
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Issiaka Soulama
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Issa Nébié
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Samuel S Serme
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Lynn Grignard
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Catriona Patterson
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Lindsey Wu
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Jessica J Briggs
- Department of Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Owen Janson
- Department of Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Shehu S Awandu
- Radboud Institute for Health Sciences and Radboud Center for Infectious Diseases, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Mireille Ouedraogo
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Casimire W Tarama
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Désiré Kargougou
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Soumanaba Zongo
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Sodiomon B Sirima
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Matthias Marti
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Chris Drakeley
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | - Alfred B Tiono
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou 01, Burkina Faso
| | - Teun Bousema
- Radboud Institute for Health Sciences and Radboud Center for Infectious Diseases, Radboud University Medical Centre, Nijmegen, The Netherlands.
| |
Collapse
|
6
|
Liposome engraftment and antigen combination potentiate the immune response towards conserved epitopes of the malaria vaccine candidate MSP2. Vaccine 2021; 39:1746-1757. [PMID: 33618946 DOI: 10.1016/j.vaccine.2021.02.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 01/30/2021] [Accepted: 02/06/2021] [Indexed: 11/23/2022]
Abstract
Merozoite surface protein 2 (MSP2) is a highly abundant, GPI-anchored surface antigen on merozoites of the malaria parasite Plasmodium falciparum. It consists of highly conserved N- and C-terminal domains, and a central polymorphic region that allows all MSP2 alleles to be categorized into the 3D7 or FC27 family. Previously it has been shown that epitope accessibility differs between lipid-bound and lipid-free MSP2, suggesting that lipid interactions modulate the conformation and antigenicity in a way that may better mimic native MSP2 on the merozoite surface. Therefore, we have immunised mice with MSP2 engrafted onto liposomes using a C-terminal tether that mimics the native GPI anchor. To improve the immunogenicity of the formulated antigen, liposomes were supplemented with Pathogen Associated Molecular Pattern molecules, specifically agonists of the Toll-like receptor 4 (TLR4) or TLR2. Induced antibodies were directed mostly towards conserved epitopes, predominantly in the conserved C-terminal region of MSP2. We also found that immunisation with a combination of 3D7 and FC27 MSP2 enhanced antibody responses to conserved epitopes, and that the overall responses of mice immunised with MSP2-engrafted liposomes were comparable in magnitude to those of mice immunised with MSP2 formulated in Montanide ISA720. The antibodies elicited in mice by immunising with MSP2-engrafted liposomes recognised the native form of parasite MSP2 on western blots and were found to be cross-reactive with isolated 3D7 and FC27 merozoites when investigated by ELISA. The liposome-tethered MSP2 induced higher titres of complement-fixing antibodies to 3D7 and FC27 MSP2 than did MSP2 formulated in Montanide ISA720. Our results indicate that liposomal formulation represents a viable strategy for eliciting a strong immune response that favours conserved epitopes in MSP2 and thus a strain-transcendent immune response.
Collapse
|
7
|
Ssewanyana I, Rek J, Rodriguez I, Wu L, Arinaitwe E, Nankabirwa JI, Beeson JG, Mayanja-Kizza H, Rosenthal PJ, Dorsey G, Kamya MR, Drakeley C, Greenhouse B, Tetteh KKA. Impact of a Rapid Decline in Malaria Transmission on Antimalarial IgG Subclasses and Avidity. Front Immunol 2021; 11:576663. [PMID: 33584643 PMCID: PMC7873448 DOI: 10.3389/fimmu.2020.576663] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 11/17/2020] [Indexed: 11/19/2022] Open
Abstract
Understanding how immunity to malaria is affected by declining transmission is important to aid vaccine design and understand disease resurgence. Both IgG subclasses and avidity of antigen-specific responses are important components of an effective immune response. Using a multiplex bead array assay, we measured the total IgG, IgG subclasses, and avidity profiles of responses to 18 P. falciparum blood stage antigens in samples from 160 Ugandans collected at two time points during high malaria transmission and two time points following a dramatic reduction in transmission. Results demonstrated that, for the antigens tested, (i) the rate of decay of total IgG following infection declined with age and was driven consistently by the decrease in IgG3 and occasionally the decrease in IgG1; (ii) the proportion of IgG3 relative to IgG1 in the absence of infection increased with age; (iii) the increase in avidity index (the strength of association between the antibody and antigen) following infection was largely due to a rapid loss of non-avid compared to avid total IgG; and (iv) both avid and non-avid total IgG in the absence of infection increased with age. Further studies are required to understand the functional differences between IgG1 and IgG3 in order to determine their contribution to the longevity of protective immunity to malaria. Measuring changes in antibody avidity may be a better approach of detecting affinity maturation compared to avidity index due to the differential expansion and contraction of high and low avidity total IgG.
Collapse
Affiliation(s)
- Isaac Ssewanyana
- Infectious Diseases Research Collaboration, Kampala, Uganda.,Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - John Rek
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Isabel Rodriguez
- Department of Medicine, University of California San Francisco, San Francisco, CA, United States
| | - Lindsey Wu
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Emmanuel Arinaitwe
- Infectious Diseases Research Collaboration, Kampala, Uganda.,Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Joaniter I Nankabirwa
- Infectious Diseases Research Collaboration, Kampala, Uganda.,School of Medicine, Makerere University, Kampala, Uganda
| | - James G Beeson
- Burnet Institute, Melbourne, VIC, Australia.,Central Clinical School, Monash University, Melbourne, VIC, Australia.,Department of Medicine, University of Melbourne, Melbourne, VIC, Australia
| | | | - Philip J Rosenthal
- Department of Medicine, University of California San Francisco, San Francisco, CA, United States
| | - Grant Dorsey
- Department of Medicine, University of California San Francisco, San Francisco, CA, United States
| | - Moses R Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda.,School of Medicine, Makerere University, Kampala, Uganda
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Bryan Greenhouse
- Department of Medicine, University of California San Francisco, San Francisco, CA, United States.,Chan Zuckerberg Biohub, San Francisco, CA, United States
| | - Kevin K A Tetteh
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| |
Collapse
|
8
|
van den Hoogen LL, Bareng P, Alves J, Reyes R, Macalinao M, Rodrigues JM, Fernandes JM, Goméz LF, Hall T, Singh SK, Fornace K, Luchavez J, Kitchen A, Chiodini P, Espino F, Tetteh KKA, Stresman G, Sepúlveda N, Drakeley C. Comparison of Commercial ELISA Kits to Confirm the Absence of Transmission in Malaria Elimination Settings. Front Public Health 2020; 8:480. [PMID: 33014975 PMCID: PMC7509087 DOI: 10.3389/fpubh.2020.00480] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 07/28/2020] [Indexed: 11/13/2022] Open
Abstract
Background: Antimalarial antibody measurements are useful because they reflect historical and recent exposure to malaria. As such, they may provide additional information to assess ongoing transmission in low endemic or pre-elimination settings where cases are rare. In addition, the absence of antibody responses in certain individuals can indicate the cessation of transmission. Commercial malaria enzyme-linked immunosorbent assays (ELISA) detect antimalarial antibodies and are commonly used to screen blood donations for possible malaria infection. However, there is no standardized test to detect antimalarial antibodies for epidemiological use. Here we compared five commercially available ELISA kits (Trinity Biotech, newbio, DiaPro, Cellabs, and NovaTec) in search of a standardized tool for supporting claims of absence of malaria transmission. For comparison, a research-based (RB) ELISA protocol was performed alongside the commercial kits. Results: The commercial kits were first compared using serum samples from known malaria-unexposed individuals (n = 223) and Toxoplasma-infected individuals (n = 191) to assess specificity and cross-reactivity against non-malaria infections. In addition, 134 samples from ≥10-year-olds collected in a hyperendemic region in the Gambia in the early 1990s were used to assess sensitivity. Three out of five kits showed high sensitivity (90–92%), high specificity (98–99%), low cross-reactivity (0–3%) and were considered user-friendly (Trinity Biotech, newbio and NovaTec). Two of these kits (Trinity Biotech and NovaTec) were taken forward for epidemiological evaluation and results were compared to those using the RB-ELISA. Samples from two pre-elimination settings (Praia, Cape Verde; n = 1,396, and Bataan, the Philippines; n = 1,824) were tested. Serological results from both the Trinity Biotech kit and the RB-ELISA concurred with recent passively detected case counts in both settings. Results from the Trinity Biotech kit reflected a significant decrease in the number of reported cases in Bataan in the 1990s better than the RB-ELISA. Results from the NovaTec kit did not reflect transmission patterns in either setting. Conclusion: The Trinity Biotech commercial ELISA kit was considered reliable for epidemiological use and accurately described transmission patterns in two (previously) malaria endemic settings. The use of this simple and standardized serological tool may aid national control and elimination programs by confirming that regions are free from malaria.
Collapse
Affiliation(s)
- Lotus L van den Hoogen
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Paolo Bareng
- Department of Health, Research Institute for Tropical Medicine, Manila, Philippines
| | - Joana Alves
- National Institute of Public Health, Praia, Cape Verde
| | - Ralph Reyes
- Department of Health, Research Institute for Tropical Medicine, Manila, Philippines
| | - Malou Macalinao
- Department of Health, Research Institute for Tropical Medicine, Manila, Philippines
| | | | - José M Fernandes
- Faculty of Science and Technology, University of Cape Verde, Praia, Cape Verde
| | - Lara F Goméz
- Department of Natural, Life and Environmental Sciences, Jean Piaget University of Cape Verde, Praia, Cape Verde
| | - Tom Hall
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Susheel K Singh
- Department of Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark.,Department of Immunology and Microbiology, Centre for Medical Parasitology, University of Copenhagen, Copenhagen, Denmark
| | - Kimberly Fornace
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Jennifer Luchavez
- Department of Health, Research Institute for Tropical Medicine, Manila, Philippines
| | - Alan Kitchen
- NHS Blood and Transplant, London, United Kingdom
| | - Peter Chiodini
- Hospital for Tropical Diseases and London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Fe Espino
- Department of Health, Research Institute for Tropical Medicine, Manila, Philippines
| | - Kevin K A Tetteh
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Gillian Stresman
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Nuno Sepúlveda
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom.,Centre of Statistics and Applications, University of Lisbon, Lisbon, Portugal
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| |
Collapse
|
9
|
van den Hoogen LL, Stresman G, Présumé J, Romilus I, Mondélus G, Elismé T, Existe A, Hamre KES, Ashton RA, Druetz T, Joseph V, Beeson JG, Singh SK, Boncy J, Eisele TP, Chang MA, Lemoine JF, Tetteh KKA, Rogier E, Drakeley C. Selection of Antibody Responses Associated With Plasmodium falciparum Infections in the Context of Malaria Elimination. Front Immunol 2020; 11:928. [PMID: 32499783 PMCID: PMC7243477 DOI: 10.3389/fimmu.2020.00928] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 04/21/2020] [Indexed: 12/30/2022] Open
Abstract
In our aim to eliminate malaria, more sensitive tools to detect residual transmission are quickly becoming essential. Antimalarial antibody responses persist in the blood after a malaria infection and provide a wider window to detect exposure to infection compared to parasite detection metrics. Here, we aimed to select antibody responses associated with recent and cumulative exposure to malaria using cross-sectional survey data from Haiti, an elimination setting. Using a multiplex bead assay, we generated data for antibody responses (immunoglobulin G) to 23 Plasmodium falciparum targets in 29,481 participants across three surveys. This included one community-based survey in which participants were enrolled during household visits and two sentinel group surveys in which participants were enrolled at schools and health facilities. First, we correlated continuous antibody responses with age (Spearman) to determine which showed strong age-related associations indicating accumulation over time with limited loss. AMA-1 and MSP-119 antibody levels showed the strongest correlation with age (0.47 and 0.43, p < 0.001) in the community-based survey, which was most representative of the underlying age structure of the population, thus seropositivity to either of these antibodies was considered representative of cumulative exposure to malaria. Next, in the absence of a gold standard for recent exposure, we included antibody responses to the remaining targets to predict highly sensitive rapid diagnostic test (hsRDT) status using receiver operating characteristic curves. For this, only data from the survey with the highest hsRDT prevalence was used (7.2%; 348/4,849). The performance of the top two antigens in the training dataset (two-thirds of the dataset; n = 3,204)-Etramp 5 ag 1 and GLURP-R0 (area-under-the-curve, AUC, 0.892 and 0.825, respectively)-was confirmed in the test dataset (remaining one-third of the dataset; n = 1,652, AUC 0.903 and 0.848, respectively). As no further improvement was seen by combining seropositivity to GLURP-R0 and Etramp 5 ag 1 (p = 0.266), seropositivity to Etramp 5 ag 1 alone was selected as representative of current or recent exposure to malaria. The validation of antibody responses associated with these exposure histories simplifies analyses and interpretation of antibody data and facilitates the application of results to evaluate programs.
Collapse
Affiliation(s)
- Lotus L. van den Hoogen
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health & Tropical Medicine, New Orleans, LA, United States
| | - Gillian Stresman
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | | | | | - Gina Mondélus
- Laboratoire National de Santé Publique, Port-au-Prince, Haiti
| | - Tamara Elismé
- Laboratoire National de Santé Publique, Port-au-Prince, Haiti
| | | | - Karen E. S. Hamre
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
- CDC Foundation, Atlanta, GA, United States
| | - Ruth A. Ashton
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health & Tropical Medicine, New Orleans, LA, United States
| | - Thomas Druetz
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health & Tropical Medicine, New Orleans, LA, United States
- Department of Social and Preventive Medicine, University of Montreal School of Public Health, Montreal, QC, Canada
| | - Vena Joseph
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health & Tropical Medicine, New Orleans, LA, United States
| | - James G. Beeson
- Burnet Institute, Melbourne, VIC, Australia
- Department of Medicine, The University of Melbourne, Melbourne, VIC, Australia
- Central Clinical School and Department of Microbiology, Monash University, Clayton, VIC, Australia
| | - Susheel K. Singh
- Department of Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark
- Department of Immunology and Microbiology, Centre for Medical Parasitology, University of Copenhagen, Copenhagen, Denmark
| | - Jacques Boncy
- Laboratoire National de Santé Publique, Port-au-Prince, Haiti
| | - Thomas P. Eisele
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health & Tropical Medicine, New Orleans, LA, United States
| | - Michelle A. Chang
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
| | - Jean F. Lemoine
- Ministère de la Santé Publique et de la Population, Port-au-Prince, Haiti
| | - Kevin K. A. Tetteh
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Eric Rogier
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| |
Collapse
|
10
|
van den Hoogen LL, Présumé J, Romilus I, Mondélus G, Elismé T, Sepúlveda N, Stresman G, Druetz T, Ashton RA, Joseph V, Eisele TP, Hamre KES, Chang MA, Lemoine JF, Tetteh KKA, Boncy J, Existe A, Drakeley C, Rogier E. Quality control of multiplex antibody detection in samples from large-scale surveys: the example of malaria in Haiti. Sci Rep 2020; 10:1135. [PMID: 31980693 PMCID: PMC6981173 DOI: 10.1038/s41598-020-57876-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 01/07/2020] [Indexed: 12/14/2022] Open
Abstract
Measuring antimalarial antibodies can estimate transmission in a population. To compare outputs, standardized laboratory testing is required. Here we describe the in-country establishment and quality control (QC) of a multiplex bead assay (MBA) for three sero-surveys in Haiti. Total IgG data against 21 antigens were collected for 32,758 participants. Titration curves of hyperimmune sera were included on assay plates, assay signals underwent 5-parameter regression, and inspection of the median and interquartile range (IQR) for the y-inflection point was used to determine assay precision. The medians and IQRs were similar for Surveys 1 and 2 for most antigens, while the IQRs increased for some antigens in Survey 3. Levey-Jennings charts for selected antigens provided a pass/fail criterion for each assay plate and, of 387 assay plates, 13 (3.4%) were repeated. Individual samples failed if IgG binding to the generic glutathione-S-transferase protein was observed, with 659 (2.0%) samples failing. An additional 455 (1.4%) observations failed due to low bead numbers (<20/analyte). The final dataset included 609,438 anti-malaria IgG data points from 32,099 participants; 96.6% of all potential data points if no QC failures had occurred. The MBA can be deployed with high-throughput data collection and low inter-plate variability while ensuring data quality.
Collapse
Affiliation(s)
- Lotus L van den Hoogen
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK.
| | | | | | - Gina Mondélus
- Laboratoire National de Santé Publique, Port-au-Prince, Haiti
| | - Tamara Elismé
- Laboratoire National de Santé Publique, Port-au-Prince, Haiti
| | - Nuno Sepúlveda
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
- Centre of Statistics and Applications, University of Lisbon, Lisbon, Portugal
| | - Gillian Stresman
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Thomas Druetz
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health & Tropical Medicine, New Orleans, Louisiana, USA
- Department of Social and Preventive Medicine, University of Montreal School of Public Health, Montreal, Canada
| | - Ruth A Ashton
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health & Tropical Medicine, New Orleans, Louisiana, USA
| | - Vena Joseph
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health & Tropical Medicine, New Orleans, Louisiana, USA
| | - Thomas P Eisele
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health & Tropical Medicine, New Orleans, Louisiana, USA
| | - Karen E S Hamre
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
- CDC Foundation, Atlanta, Georgia, USA
| | - Michelle A Chang
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Jean F Lemoine
- Ministère de la santé publique et de la population, Port-au-Prince, Haiti
| | - Kevin K A Tetteh
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Jacques Boncy
- Laboratoire National de Santé Publique, Port-au-Prince, Haiti
| | | | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Eric Rogier
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| |
Collapse
|
11
|
Tiendrebeogo RW, Spallek R, Oehlmann W, Singh M, Theisen M, Nebie I, Moret R, Roussilhon C, Corradin G. Immunogenicity of a recombinant fusion construct composed of intrinsically unstructured, low polymorphic segments derived from merozoite surface protein 2 and trophozoite exported protein 1. Vaccine 2019; 37:5332-5340. [PMID: 31358409 DOI: 10.1016/j.vaccine.2019.07.048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 06/20/2019] [Accepted: 07/11/2019] [Indexed: 10/26/2022]
Abstract
To overcome the extensive polymorphism found in human Plasmodium antigens and to avoid the lengthy characterization of their 3 dimensional structure and subsequent production of the native proteins we have been concentrated in large unstructured, non-or low-polymorphic fragments present in the blood stage of P. falciparum. Three fragments derived from the 2 family-specific and constant regions of merozoite surface protein (MSP2) and PFF0165c protein were previously selected for evaluation as potential single vaccine candidates. In order to increase and optimize their potential efficacy against P. falciparum infection the 3 antigens were combined in a single DNA recombinant product (FusN) and compared its antigenicity with that of single antigens in sera of volunteers living in endemic countries. Immunogenicity of the FusN was then compared with that of the mixture of 3 antigens in 3 strains of mice. Antigen specific, affinity purified human antibodies were then tested in antibody dependent cellular inhibition and merozoite opsonization assays. In addition, the antigen specific antibody response and its association with protection from malaria infection were determined. The data collected indicate that the recombinant product is an equal or better antigen /immunogen than fragments used either alone or as a mixture for vaccination in combination with adjuvant. In addition, antibody response to FusN shows a stronger association with protection than single fragments. The use of a single construct as vaccine would drastically reduce the cost of manufacturing and development of the GMP product.
Collapse
Affiliation(s)
- Regis Wendpayangde Tiendrebeogo
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark; Department for Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark
| | - Ralf Spallek
- LIONEX Diagnostics & Therapeutics GmbH, 38126 Braunschweig, Germany
| | - Wulf Oehlmann
- LIONEX Diagnostics & Therapeutics GmbH, 38126 Braunschweig, Germany
| | - Mahavir Singh
- LIONEX Diagnostics & Therapeutics GmbH, 38126 Braunschweig, Germany
| | - Michael Theisen
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark; Department for Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark
| | - Issa Nebie
- Centre National de Recherche et de Formation sur le Paludisme, BP 2208, Ouagadougou 01, Burkina Faso
| | - Remy Moret
- ASAREN 01BP3916, Ouagadougou 01, Burkina Faso
| | | | - Giampietro Corradin
- Biochemistry Department, University of Lausanne, 1066 Epalinges, Switzerland.
| |
Collapse
|
12
|
Jaenisch T, Heiss K, Fischer N, Geiger C, Bischoff FR, Moldenhauer G, Rychlewski L, Sié A, Coulibaly B, Seeberger PH, Wyrwicz LS, Breitling F, Loeffler FF. High-density Peptide Arrays Help to Identify Linear Immunogenic B-cell Epitopes in Individuals Naturally Exposed to Malaria Infection. Mol Cell Proteomics 2019; 18:642-656. [PMID: 30630936 PMCID: PMC6442360 DOI: 10.1074/mcp.ra118.000992] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 11/28/2018] [Indexed: 01/31/2023] Open
Abstract
High-density peptide arrays are an excellent means to profile anti-plasmodial antibody responses. Different protein intrinsic epitopes can be distinguished, and additional insights are gained, when compared with assays involving the full-length protein. Distinct reactivities to specific epitopes within one protein may explain differences in published results, regarding immunity or susceptibility to malaria. We pursued three approaches to find specific epitopes within important plasmodial proteins, (1) twelve leading vaccine candidates were mapped as overlapping 15-mer peptides, (2) a bioinformatical approach served to predict immunogenic malaria epitopes which were subsequently validated in the assay, and (3) randomly selected peptides from the malaria proteome were screened as a control. Several peptide array replicas were prepared, employing particle-based laser printing, and were used to screen 27 serum samples from a malaria-endemic area in Burkina Faso, West Africa. The immunological status of the individuals was classified as "protected" or "unprotected" based on clinical symptoms, parasite density, and age. The vaccine candidate screening approach resulted in significant hits in all twelve proteins and allowed us (1) to verify many known immunogenic structures, (2) to map B-cell epitopes across the entire sequence of each antigen and (3) to uncover novel immunogenic epitopes. Predicting immunogenic regions in the proteome of the human malaria parasite Plasmodium falciparum, via the bioinformatics approach and subsequent array screening, confirmed known immunogenic sequences, such as in the leading malaria vaccine candidate CSP and discovered immunogenic epitopes derived from hypothetical or unknown proteins.
Collapse
Affiliation(s)
- Thomas Jaenisch
- From the ‡Center for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Im Neuenheimer Feld 324, D 69120 Heidelberg, Germany;; §German Center for Infectious Disease Research, Heidelberg (DZIF);; ¶HEiKA - Heidelberg Karlsruhe Research Partnership, Heidelberg University, Karlsruhe Institute of Technology (KIT), Germany;.
| | - Kirsten Heiss
- From the ‡Center for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Im Neuenheimer Feld 324, D 69120 Heidelberg, Germany;; §German Center for Infectious Disease Research, Heidelberg (DZIF)
| | - Nico Fischer
- From the ‡Center for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Im Neuenheimer Feld 324, D 69120 Heidelberg, Germany;; §German Center for Infectious Disease Research, Heidelberg (DZIF);; ¶HEiKA - Heidelberg Karlsruhe Research Partnership, Heidelberg University, Karlsruhe Institute of Technology (KIT), Germany
| | - Carolin Geiger
- From the ‡Center for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Im Neuenheimer Feld 324, D 69120 Heidelberg, Germany;; §German Center for Infectious Disease Research, Heidelberg (DZIF)
| | - F Ralf Bischoff
- ‖German Cancer Research Center, Im Neuenheimer Feld 280, D 69120 Heidelberg, Germany
| | - Gerhard Moldenhauer
- ‖German Cancer Research Center, Im Neuenheimer Feld 280, D 69120 Heidelberg, Germany
| | - Leszek Rychlewski
- BioInfoBank Institute, Św. Marcin 80/82 lok. 355, 61-809 Poznań, Poland
| | - Ali Sié
- Centre de Recherche en Santé de Nouna, BP 02 Nouna, Rue Namory Keita, Burkina Faso
| | - Boubacar Coulibaly
- Centre de Recherche en Santé de Nouna, BP 02 Nouna, Rue Namory Keita, Burkina Faso
| | - Peter H Seeberger
- §§Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, D 14476 Potsdam, Germany
| | - Lucjan S Wyrwicz
- Department of Oncology and Radiotherapy, M Sklodowska Curie Memorial Cancer Center, Wawelska 15, 02-034 Warsaw, Poland
| | - Frank Breitling
- ‖‖Institute of Microstructure Technology, Karlsruhe Institute of Technology, Germany Hermann-von-Helmholtz-Platz 1, D 76344 Eggenstein-Leopoldshafen, Germany
| | - Felix F Loeffler
- ¶HEiKA - Heidelberg Karlsruhe Research Partnership, Heidelberg University, Karlsruhe Institute of Technology (KIT), Germany;; §§Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, D 14476 Potsdam, Germany;.
| |
Collapse
|
13
|
Dobaño C, Santano R, Vidal M, Jiménez A, Jairoce C, Ubillos I, Dosoo D, Aguilar R, Williams NA, Díez-Padrisa N, Ayestaran A, Valim C, Asante KP, Owusu-Agyei S, Lanar D, Chauhan V, Chitnis C, Dutta S, Angov E, Gamain B, Coppel RL, Beeson JG, Reiling L, Gaur D, Cavanagh D, Gyan B, Nhabomba AJ, Campo JJ, Moncunill G. Differential Patterns of IgG Subclass Responses to Plasmodium falciparum Antigens in Relation to Malaria Protection and RTS,S Vaccination. Front Immunol 2019; 10:439. [PMID: 30930896 PMCID: PMC6428712 DOI: 10.3389/fimmu.2019.00439] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 02/19/2019] [Indexed: 12/24/2022] Open
Abstract
Naturally acquired immunity (NAI) to Plasmodium falciparum malaria is mainly mediated by IgG antibodies but the subclasses, epitope targets and effector functions have not been unequivocally defined. Dissecting the type and specificity of antibody responses mediating NAI is a key step toward developing more effective vaccines to control the disease. We investigated the role of IgG subclasses to malaria antigens in protection against disease and the factors that affect their levels, including vaccination with RTS,S/AS01E. We analyzed plasma and serum samples at baseline and 1 month after primary vaccination with RTS,S or comparator in African children and infants participating in a phase 3 trial in two sites of different malaria transmission intensity: Kintampo in Ghana and Manhiça in Mozambique. We used quantitative suspension array technology (qSAT) to measure IgG1−4 responses to 35 P. falciparum pre-erythrocytic and blood stage antigens. Our results show that the pattern of IgG response is predominantly IgG1 or IgG3, with lower levels of IgG2 and IgG4. Age, site and RTS,S vaccination significantly affected antibody subclass levels to different antigens and susceptibility to clinical malaria. Univariable and multivariable analysis showed associations with protection mainly for cytophilic IgG3 levels to selected antigens, followed by IgG1 levels and, unexpectedly, also with IgG4 levels, mainly to antigens that increased upon RTS,S vaccination such as MSP5 and MSP1 block 2, among others. In contrast, IgG2 was associated with malaria risk. Stratified analysis in RTS,S vaccinees pointed to novel associations of IgG4 responses with immunity mainly involving pre-erythrocytic antigens upon RTS,S vaccination. Multi-marker analysis revealed a significant contribution of IgG3 responses to malaria protection and IgG2 responses to malaria risk. We propose that the pattern of cytophilic and non-cytophilic IgG antibodies is antigen-dependent and more complex than initially thought, and that mechanisms of both types of subclasses could be involved in protection. Our data also suggests that RTS,S efficacy is significantly affected by NAI, and indicates that RTS,S vaccination significantly alters NAI.
Collapse
Affiliation(s)
- Carlota Dobaño
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.,Centro de Investigação em Saúde de Manhiça (CISM), Manhiça, Mozambique
| | - Rebeca Santano
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
| | - Marta Vidal
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
| | - Alfons Jiménez
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.,Spanish Consortium for Research in Epidemiology and Public Health (CIBERESP), Barcelona, Spain
| | - Chenjerai Jairoce
- Centro de Investigação em Saúde de Manhiça (CISM), Manhiça, Mozambique
| | - Itziar Ubillos
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
| | - David Dosoo
- Kintampo Health Research Centre, Kintampo, Ghana
| | - Ruth Aguilar
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
| | - Nana Aba Williams
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
| | | | | | - Clarissa Valim
- Department of Osteopathic Medical Specialties, Michigan State University, East Lansing, MI, United States.,Department of Immunology and Infectious Diseases, Harvard T.H. Chen School of Public Health, Boston, MA, United States
| | | | - Seth Owusu-Agyei
- Kintampo Health Research Centre, Kintampo, Ghana.,Disease Control Department, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - David Lanar
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Virander Chauhan
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Chetan Chitnis
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Sheetij Dutta
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Evelina Angov
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Benoit Gamain
- Unité Biologie Intégrée du Globule Rouge, Laboratoire d'Excellence GR-Ex, UMR_S1134, Inserm, INTS, Université Sorbonne Paris Cité, Université Paris Diderot, Paris, France
| | - Ross L Coppel
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Melbourne, VIC, Australia
| | | | | | - Deepak Gaur
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India.,Laboratory of Malaria and Vaccine Research, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - David Cavanagh
- Ashworth Laboratories, Centre for Immunity, Infection and Evolution, School of Biological Sciences, Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, United Kingdom
| | - Ben Gyan
- Kintampo Health Research Centre, Kintampo, Ghana.,Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | | | - Joseph J Campo
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.,Centro de Investigação em Saúde de Manhiça (CISM), Manhiça, Mozambique
| | - Gemma Moncunill
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.,Centro de Investigação em Saúde de Manhiça (CISM), Manhiça, Mozambique
| |
Collapse
|
14
|
Antibody responses to Plasmodium vivax Duffy binding and Erythrocyte binding proteins predict risk of infection and are associated with protection from clinical Malaria. PLoS Negl Trop Dis 2019; 13:e0006987. [PMID: 30768655 PMCID: PMC6400399 DOI: 10.1371/journal.pntd.0006987] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 03/05/2019] [Accepted: 11/12/2018] [Indexed: 01/05/2023] Open
Abstract
Background The Plasmodium vivax Duffy Binding Protein (PvDBP) is a key target of naturally acquired immunity. However, region II of PvDBP, which contains the receptor-binding site, is highly polymorphic. The natural acquisition of antibodies to different variants of PvDBP region II (PvDBPII), including the AH, O, P and Sal1 alleles, the central region III-V (PvDBPIII-V), and P. vivax Erythrocyte Binding Protein region II (PvEBPII) and their associations with risk of clinical P. vivax malaria are not well understood. Methodology Total IgG and IgG subclasses 1, 2, and 3 that recognize four alleles of PvDBPII (AH, O, P, and Sal1), PvDBPIII-V and PvEBPII were measured in samples collected from a cohort of 1 to 3 year old Papua New Guinean (PNG) children living in a highly endemic area of PNG. The levels of binding inhibitory antibodies (BIAbs) to PvDBPII (AH, O, and Sal1) were also tested in a subset of children. The association of presence of IgG with age, cumulative exposure (measured as the product of age and malaria infections during follow-up) and prospective risk of clinical malaria were evaluated. Results The increase in antigen-specific total IgG, IgG1, and IgG3 with age and cumulative exposure was only observed for PvDBPII AH and PvEBPII. High levels of total IgG and predominant subclass IgG3 specific for PvDBPII AH were associated with decreased incidence of clinical P. vivax episodes (aIRR = 0.56–0.68, P≤0.001–0.021). High levels of total IgG and IgG1 to PvEBPII correlated strongly with protection against clinical vivax malaria compared with IgGs against all PvDBPII variants (aIRR = 0.38, P<0.001). Antibodies to PvDBPII AH and PvEBPII showed evidence of an additive effect, with a joint protective association of 70%. Conclusion Antibodies to the key parasite invasion ligands PvDBPII and PvEBPII are good correlates of protection against P. vivax malaria in PNG. This further strengthens the rationale for inclusion of PvDBPII in a recombinant subunit vaccine for P. vivax malaria and highlights the need for further functional studies to determine the potential of PvEBPII as a component of a subunit vaccine for P. vivax malaria. Plasmodium vivax is responsible for most malaria infections outside Africa, with 13.8 million vivax malaria cases reported annually worldwide. Antibodies are a key component of the host response to P. vivax infection, and their study can assist in identifying suitable vaccine candidates and serological biomarkers for malaria surveillance. The binding of P. vivax Duffy binding protein region II (PvDBPII) to the Duffy Antigen Receptor for Chemokines (DARC) is critical for P. vivax invasion of reticulocytes. Although the binding residues for DARC are highly conserved across PvDBPII, the parasite displays high sequence diversity in non-binding residues of PvDBPII. Other regions such as PvDBPIII-V are relatively conserved. Recently, sequencing of P. vivax field isolates, identified a homologous erythrocyte-binding protein (PvEBP), which harbors a domain, region II (PvEBPII), that is homologous to PvDBPII. To date, there has been limited investigation into the naturally acquired immunity to both PvDBPIII-V and PvEBPII in human populations. Using a longitudinal cohort study, we have characterized the serological response to PvDBPII, PvDBPIII-V, and PvEBPII among 1–3 years old PNG children and investigated associations with protection against clinical malaria. This study shows that both total IgG and IgG3 to the predominant PvDBPII AH allele in PNG, and total IgG and IgG1 to PvEBPII were associated with protection from P. vivax malaria.
Collapse
|
15
|
Yman V, White MT, Asghar M, Sundling C, Sondén K, Draper SJ, Osier FHA, Färnert A. Antibody responses to merozoite antigens after natural Plasmodium falciparum infection: kinetics and longevity in absence of re-exposure. BMC Med 2019; 17:22. [PMID: 30696449 PMCID: PMC6352425 DOI: 10.1186/s12916-019-1255-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 01/08/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Antibodies against merozoite antigens are key components of malaria immunity. The naturally acquired antibody response to these antigens is generally considered short-lived; however, the underlying mechanisms remain unclear. Prospective studies of travellers with different levels of prior exposure, returning to malaria-free countries with Plasmodium infection, offer a unique opportunity to investigate the kinetics and composition of the antibody response after natural infection. METHODS Adults diagnosed with P. falciparum malaria in Stockholm, Sweden (20 likely malaria naïve and 41 with repeated previous exposure during residency in sub-Saharan Africa) were sampled at diagnosis and 10 days and 1, 3, 6, and 12 months after treatment. Total and subclass-specific IgG responses to P. falciparum merozoite antigens (AMA-1, MSP-119, MSP-2, MSP-3, and RH5) and tetanus toxoid were measured by multiplex bead-based immunoassays and ELISA. Mathematical modelling was used to estimate the exposure-dependent longevity of antibodies and antibody-secreting cells (ASCs). RESULTS A majority of individuals mounted detectable antibody responses towards P. falciparum merozoite antigens at diagnosis; however, the magnitude and breadth were greater in individuals with prior exposure. In both exposure groups, antibody levels increased rapidly for 2 weeks and decayed thereafter. Previously exposed individuals maintained two- to ninefold greater antibody levels throughout the 1-year follow-up. The half-lives of malaria-specific long-lived ASCs, responsible for maintaining circulating antibodies, ranged from 1.8 to 3.7 years for merozoite antigens and were considerably short compared to tetanus-specific ASCs. Primary infected individuals did acquire a long-lived component of the antibody response; however, the total proportion of long-lived ASCs generated in response to infection was estimated not to exceed 10%. In contrast, previously exposed individuals maintained substantially larger numbers of long-lived ASCs (10-56% of total ASCs). CONCLUSION The short-lived nature of the naturally acquired antibody response, to all tested merozoite antigens, following primary malaria infection can be attributed to a combination of a poor acquisition and short half-life of long-lived ASCs. Greater longevity is acquired with repeated infections and can be explained by the maintenance of larger numbers of long-lived ASCs. These insights advance our understanding of naturally acquired malaria immunity and will guide strategies for further development of both vaccines and serological tools to monitor exposure.
Collapse
Affiliation(s)
- Victor Yman
- Division of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Karolinska University Hospital, 171 76, Stockholm, Sweden.
| | - Michael T White
- Department of Parasites and Insect Vectors, Institut Pasteur, 25-28 Rue du Dr Roux, 75015, Paris, France
| | - Muhammad Asghar
- Division of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Karolinska University Hospital, 171 76, Stockholm, Sweden
| | - Christopher Sundling
- Division of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Karolinska University Hospital, 171 76, Stockholm, Sweden
| | - Klara Sondén
- Division of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Karolinska University Hospital, 171 76, Stockholm, Sweden
- Department of Infectious Diseases, Karolinska University Hospital, 171 76, Stockholm, Sweden
| | - Simon J Draper
- Jenner Institute, University of Oxford, Oxford, OX3 7DQ, UK
| | - Faith H A Osier
- Kenya Medical Research Institute - Wellcome Trust Research Program, Centre for Geographic Medicine Research-Coast, PO Box 230-80108, Kilifi, Kenya
- Centre for Infectious Diseases, Parasitology, Heidelberg University Hospital, Im Neuenheimer Feld 324, 69120, Heidelberg, Germany
| | - Anna Färnert
- Division of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Karolinska University Hospital, 171 76, Stockholm, Sweden
- Department of Infectious Diseases, Karolinska University Hospital, 171 76, Stockholm, Sweden
| |
Collapse
|
16
|
Mbengue B, Fall MM, Varela ML, Loucoubar C, Joos C, Fall B, Niang MS, Niang B, Mbow M, Dieye A, Perraut R. Analysis of antibody responses to selected Plasmodium falciparum merozoite surface antigens in mild and cerebral malaria and associations with clinical outcomes. Clin Exp Immunol 2019; 196:86-96. [PMID: 30580455 DOI: 10.1111/cei.13254] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/13/2018] [Indexed: 11/28/2022] Open
Abstract
Merozoite surface proteins (MSPs) are critical for parasite invasion; they represent attractive targets for antibody-based protection against clinical malaria. To identify protection-associated target MSPs, the present study analysed antibody responses to whole merozoite extract (ME) and to defined MSP recombinant antigens in hospitalized patients from a low endemic urban area as a function of disease severity (mild versus cerebral malaria). Sera from 110 patients with confirmed severe cerebral malaria (CM) and 91 patients with mild malaria (MM) were analysed (mean age = 29 years) for total and subclass immunoglobulin (Ig)G to ME and total IgG to MSP1p19, MSP2, MSP3, MSP4 and MSP5 by enzyme-linked immunosorbent assay (ELISA). Functional antibody responses were evaluated using the antibody-dependent respiratory burst (ADRB) assay in a subset of sera. There was a trend towards higher IgG1 and IgG4 levels to ME in CM compared to MM; only ME IgM responses differed significantly between fatal and surviving CM patients. Increased prevalence of IgG to individual MSPs was found in the CM compared to the MM group, including significantly higher levels of IgG to MSP4 and MSP5 in the former. Sera from fatal (24·5%) versus surviving cases showed significantly lower IgG to MSP1p19 and MSP3 (P < 0·05). ADRB assay readouts correlated with high levels of anti-MSP IgG, and trended higher in sera from patients with surviving compared to fatal CM outcome (P = 0·07). These results document strong differential antibody responses to MSP antigens as targets of protective immunity against CM and in particular MSP1p19 and MSP3 as prognostic indicators.
Collapse
Affiliation(s)
- B Mbengue
- Service d'Immunologie FMPO, Université Cheikh Anta Diop de Dakar, Senegal.,Unité d'Immunogénétique, Institut Pasteur de Dakar, IPD, Senegal
| | - M M Fall
- Service de Réanimation, Hôpital Principal de Dakar, HPD, Senegal
| | - M-L Varela
- Unité d'Immunologie, Institut Pasteur de Dakar, IPD, Senegal
| | - C Loucoubar
- Groupe de Biostatistique et Bioinformatique, IPD, Senegal
| | - C Joos
- Unité d'Immunologie, Institut Pasteur de Dakar, IPD, Senegal
| | - B Fall
- Fédération des Laboratoires, Hôpital Principal de Dakar, HPD, Senegal
| | - M S Niang
- Service d'Immunologie FMPO, Université Cheikh Anta Diop de Dakar, Senegal
| | - B Niang
- Service de Réanimation, Hôpital Principal de Dakar, HPD, Senegal
| | - M Mbow
- Service d'Immunologie FMPO, Université Cheikh Anta Diop de Dakar, Senegal
| | - A Dieye
- Service d'Immunologie FMPO, Université Cheikh Anta Diop de Dakar, Senegal.,Unité d'Immunogénétique, Institut Pasteur de Dakar, IPD, Senegal
| | - R Perraut
- Unité d'Immunogénétique, Institut Pasteur de Dakar, IPD, Senegal.,Unité d'Immunologie, Institut Pasteur de Dakar, IPD, Senegal
| |
Collapse
|
17
|
Kamuyu G, Tuju J, Kimathi R, Mwai K, Mburu J, Kibinge N, Chong Kwan M, Hawkings S, Yaa R, Chepsat E, Njunge JM, Chege T, Guleid F, Rosenkranz M, Kariuki CK, Frank R, Kinyanjui SM, Murungi LM, Bejon P, Färnert A, Tetteh KKA, Beeson JG, Conway DJ, Marsh K, Rayner JC, Osier FHA. KILchip v1.0: A Novel Plasmodium falciparum Merozoite Protein Microarray to Facilitate Malaria Vaccine Candidate Prioritization. Front Immunol 2018; 9:2866. [PMID: 30619257 PMCID: PMC6298441 DOI: 10.3389/fimmu.2018.02866] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 11/21/2018] [Indexed: 12/12/2022] Open
Abstract
Passive transfer studies in humans clearly demonstrated the protective role of IgG antibodies against malaria. Identifying the precise parasite antigens that mediate immunity is essential for vaccine design, but has proved difficult. Completion of the Plasmodium falciparum genome revealed thousands of potential vaccine candidates, but a significant bottleneck remains in their validation and prioritization for further evaluation in clinical trials. Focusing initially on the Plasmodium falciparum merozoite proteome, we used peer-reviewed publications, multiple proteomic and bioinformatic approaches, to select and prioritize potential immune targets. We expressed 109 P. falciparum recombinant proteins, the majority of which were obtained using a mammalian expression system that has been shown to produce biologically functional extracellular proteins, and used them to create KILchip v1.0: a novel protein microarray to facilitate high-throughput multiplexed antibody detection from individual samples. The microarray assay was highly specific; antibodies against P. falciparum proteins were detected exclusively in sera from malaria-exposed but not malaria-naïve individuals. The intensity of antibody reactivity varied as expected from strong to weak across well-studied antigens such as AMA1 and RH5 (Kruskal–Wallis H test for trend: p < 0.0001). The inter-assay and intra-assay variability was minimal, with reproducible results obtained in re-assays using the same chip over a duration of 3 months. Antibodies quantified using the multiplexed format in KILchip v1.0 were highly correlated with those measured in the gold-standard monoplex ELISA [median (range) Spearman's R of 0.84 (0.65–0.95)]. KILchip v1.0 is a robust, scalable and adaptable protein microarray that has broad applicability to studies of naturally acquired immunity against malaria by providing a standardized tool for the detection of antibody correlates of protection. It will facilitate rapid high-throughput validation and prioritization of potential Plasmodium falciparum merozoite-stage antigens paving the way for urgently needed clinical trials for the next generation of malaria vaccines.
Collapse
Affiliation(s)
- Gathoni Kamuyu
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya.,Centre for Infectious Diseases, Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| | - James Tuju
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya.,Department of Biochemistry, Pwani University, Kilifi, Kenya
| | - Rinter Kimathi
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Kennedy Mwai
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - James Mburu
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Nelson Kibinge
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Marisa Chong Kwan
- Arrayjet, Innovative Microarray Solutions, Edinburgh, United Kingdom
| | - Sam Hawkings
- Arrayjet, Innovative Microarray Solutions, Edinburgh, United Kingdom
| | - Reuben Yaa
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Emily Chepsat
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - James M Njunge
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Timothy Chege
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Fatuma Guleid
- Department of Pathology, University of Cape Town, Cape Town, South Africa
| | - Micha Rosenkranz
- Centre for Infectious Diseases, Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| | - Christopher K Kariuki
- Department of Tropical and Infectious Diseases, Institute of Primate Research, Nairobi, Kenya.,Cellular and Molecular Immunology, Vrije Universiteit Brussels, Brussels, Belgium
| | - Roland Frank
- Centre for Infectious Diseases, Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| | - Samson M Kinyanjui
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya.,Department of Biochemistry, Pwani University, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Linda M Murungi
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Anna Färnert
- Division of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.,Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Kevin K A Tetteh
- Immunology and Infection Department, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - James G Beeson
- Burnet Institute, Melbourne, VIC, Australia.,Central Clinical School, Monash University, Melbourne, VIC, Australia.,Department of Medicine, University of Melbourne, Melbourne, VIC, Australia
| | - David J Conway
- Pathogen Molecular Biology Department, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Kevin Marsh
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom.,African Academy of Sciences, Nairobi, Kenya
| | - Julian C Rayner
- Wellcome Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Faith H A Osier
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya.,Centre for Infectious Diseases, Parasitology, Heidelberg University Hospital, Heidelberg, Germany.,Department of Biochemistry, Pwani University, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| |
Collapse
|
18
|
Amoah LE, Abagna HB, Akyea-Mensah K, Lo AC, Kusi KA, Gyan BA. Characterization of anti-EBA175RIII-V in asymptomatic adults and children living in communities in the Greater Accra Region of Ghana with varying malaria transmission intensities. BMC Immunol 2018; 19:34. [PMID: 30453898 PMCID: PMC6245760 DOI: 10.1186/s12865-018-0271-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 11/08/2018] [Indexed: 11/10/2022] Open
Abstract
Background Antibodies against Region III-V of the erythrocyte binding antigen (EBA) 175 (EBA175RIII-V) have been suggested to provide protection from malaria in a natural infection. However, the quality and quantity of naturally induced antibodies to EBA175RIII-V has not been fully characterized in different cohorts of Ghanaians. This study sought to determine the characteristics of antibodies against EBA175RIII-V in asymptomatic adults and children living in two communities of varying P. falciparum parasite prevalence in southern Ghana. Methods Microscopic evaluation of thick and thin blood smears was used to identify asymptomatic Plasmodium falciparum carriage and indirect enzyme linked immunosorbent (ELISA) used to assess antibody concentrations and avidity. Results Parasite carriage estimated by microscopy in Obom was 35.6% as opposed to 3.5% in Asutsuare. Levels of IgG, IgG1, IgG2, IgG3 and IgG4 against EBA175RIII-V in the participants from Obom were significantly higher (P < 0.05, Dunn’s Multiple Comparison test) than those in Asutsuare. However the relative avidity of IgG antibodies against EBA175RIII-V was significantly higher (P < 0.0001, Mann Whitney test) in Asutsuare than in Obom. Conclusions People living in communities with limited exposure to P. falciparum parasites have low quantities of high avidity antibodies against EBA175RIII-V whilst people living in communities with high exposure to the parasites have high quantities of age-dependent but low avidity antibodies against EBA175RIII-V. Electronic supplementary material The online version of this article (10.1186/s12865-018-0271-y) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- L E Amoah
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana.
| | - H B Abagna
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - K Akyea-Mensah
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - A C Lo
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana.,Present address: University Cheikh Anta DIOP, Dakar, Senegal
| | - K A Kusi
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - B A Gyan
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| |
Collapse
|
19
|
Feng G, Boyle MJ, Cross N, Chan JA, Reiling L, Osier F, Stanisic DI, Mueller I, Anders RF, McCarthy JS, Richards JS, Beeson JG. Human Immunization With a Polymorphic Malaria Vaccine Candidate Induced Antibodies to Conserved Epitopes That Promote Functional Antibodies to Multiple Parasite Strains. J Infect Dis 2018; 218:35-43. [PMID: 29584918 PMCID: PMC6904323 DOI: 10.1093/infdis/jiy170] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 03/22/2018] [Indexed: 12/15/2022] Open
Abstract
Background Overcoming antigenic diversity is a key challenge in the development of effective Plasmodium falciparum malaria vaccines. Strategies that promote the generation of antibodies targeting conserved epitopes of vaccine antigens may provide protection against diverse parasites strains. Understanding differences between vaccine-induced and naturally acquired immunity is important to achieving this goal. Methods We analyzed antibodies generated in a phase 1 human vaccine trial, MSP2-C1, which included 2 allelic forms of MSP2, an abundant vaccine antigen on the merozoite surface. Vaccine-induced responses were assessed for functional activity against multiple parasite strains, and cross-reactivity of antibodies was determined using competition ELISA and epitope mapping approaches. Results Vaccination induced cytophilic antibody responses with strain-transcending opsonic phagocytosis and complement-fixing function. In contrast to antibodies acquired via natural infection, vaccine-induced antibodies were directed towards conserved epitopes at the C-terminus of MSP2, whereas naturally acquired antibodies mainly targeted polymorphic epitopes. Functional activity of C-terminal-targeted antibodies was confirmed using monoclonal antibodies that promoted opsonic phagocytosis against multiple parasite strains. Conclusion Vaccination generated markedly different responses to polymorphic antigens than naturally acquired immunity and targeted conserved functional epitopes. Induction of antibodies targeting conserved regions of malaria antigens provides a promising vaccine strategy to overcome antigenic diversity for developing effective malaria vaccines.
Collapse
Affiliation(s)
- Gaoqian Feng
- Burnet Institute, Melbourne
- Department of Medicine, University of Melbourne, Parkville, Australia
| | | | | | | | | | - Faith Osier
- Burnet Institute, Melbourne
- Centre for Geographic Medicine - Coast, Kenya Medical Research Institute, Kilifi, Kenya
- Department of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Germany
| | | | - Ivo Mueller
- Walter and Eliza Hall Institute of Medical Research, Parkville
| | - Robin F Anders
- Department of Biochemistry and Genetics, La Trobe University, Melbourne
| | - James S McCarthy
- Clinical Tropical Medicine Laboratory, Queensland Institute of Medical Research Berghofer Medical Research Institute, Herston
| | - Jack S Richards
- Burnet Institute, Melbourne
- Department of Medicine, University of Melbourne, Parkville, Australia
- Central Clinical School and Department of Microbiology, Monash University, Melbourne, Australia
| | - James G Beeson
- Burnet Institute, Melbourne
- Department of Medicine, University of Melbourne, Parkville, Australia
- Central Clinical School and Department of Microbiology, Monash University, Melbourne, Australia
| |
Collapse
|
20
|
Nasr A, Saleh AM, Eltoum M, Abushouk A, Hamza A, Aljada A, El-Toum ME, Abu-Zeid YA, Allam G, ElGhazali G. Antibody responses to P. falciparum Apical Membrane Antigen 1(AMA-1) in relation to haemoglobin S (HbS), HbC, G6PD and ABO blood groups among Fulani and Masaleit living in Western Sudan. Acta Trop 2018; 182:115-123. [PMID: 29486174 DOI: 10.1016/j.actatropica.2018.02.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 02/12/2018] [Accepted: 02/23/2018] [Indexed: 01/02/2023]
Abstract
Fulani and Masaleit are two sympatric ethnic groups in western Sudan who are characterised by marked differences in susceptibility to Plasmodium falciparum malaria. It has been demonstrated that Glucose-6-phosphate dehydrogenase (G6PD) deficiency and Sickle cell trait HbAS carriers are protected from the most severe forms of malaria. This study aimed to investigate a set of specific IgG subclasses against P. falciparum Apical Membrane Antigen 1 (AMA-1 3D7), haemoglobin variants and (G6PD) in association with malaria susceptibility among Fulani ethnic group compared to sympatric ethnic group living in Western Sudan. A total of 124 children aged 5-9 years from each tribe living in an area of hyper-endemic P. falciparum unstable malaria transmission were recruited and genotyped for the haemoglobin (Hb) genes, (G6PD) and (ABO) blood groups. Furthermore, the level of plasma IgG antibody subclasses against P. falciparum antigen (AMA-1) were measured using enzyme linked immunosorbent assays (ELISA). Higher levels of anti-malarial IgG1, IgG2 and IgG3 but not IgG4 antibody were found in Fulani when compared to Masaleit. Individuals carrying the HbCC phenotype were significantly associated with higher levels of IgG1 and IgG2. Furthermore, individuals having the HbAS phenotype were associated with higher levels of specific IgG2 and IgG4 antibodies. In addition, patients with G6PD A/A genotype were associated with higher levels of specific IgG2 antibody compared with those carrying the A/G and G/G genotypes. The results indicate that the Fulani ethnic group show lower frequency of HbAS, HbSS and HbAC compared to the Masaleit ethnic group. The inter-ethnic analysis shows no statistically significant difference in G6PD genotypes (P value = 0.791). However, the intra-ethnic analysis indicates that both ethnic groups have less A/A genotypes and (A) allele frequency of G6PD compared to G/G genotypes, while the HbSA genotype was associated with higher levels of IgG2 (AMA-1) and IgG4 antibodies. In addition, patients carrying the G6PD A/A genotype were associated with higher levels of specific IgG2 antibody compared with those carrying the A/G and G/G genotypes. The present results revealed that the Fulani ethnic group has statistically significantly lower frequency of abnormal haemoglobin resistant to malaria infection compared to the Masaleit ethnic group.
Collapse
|
21
|
Patel P, Bharti PK, Bansal D, Raman RK, Mohapatra PK, Sehgal R, Mahanta J, Sultan AA, Singh N. Genetic diversity and antibody responses against Plasmodium falciparum vaccine candidate genes from Chhattisgarh, Central India: Implication for vaccine development. PLoS One 2017; 12:e0182674. [PMID: 28787005 PMCID: PMC5546615 DOI: 10.1371/journal.pone.0182674] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 07/21/2017] [Indexed: 11/22/2022] Open
Abstract
The genetic diversity in Plasmodium falciparum antigens is a major hurdle in developing an effective malaria vaccine. Protective efficacy of the vaccine is dependent on the polymorphic alleles of the vaccine candidate antigens. Therefore, we investigated the genetic diversity of the potential vaccine candidate antigens i.e. msp-1, msp-2, glurp, csp and pfs25 from field isolates of P.falciparum and determined the natural immune response against the synthetic peptide of these antigens. Genotyping was performed using Sanger method and size of alleles, multiplicity of infection, heterogeneity and recombination rate were analyzed. Asexual stage antigens were highly polymorphic with 55 and 50 unique alleles in msp-1 and msp-2 genes, respectively. The MOI for msp-1 and msp-2 were 1.67 and 1.28 respectively. A total 59 genotype was found in glurp gene with 8 types of amino acid repeats in the conserved part of RII repeat region. The number of NANP repeats from 40 to 44 was found among 55% samples in csp gene while pfs25 was found almost conserved with only two amino acid substitution site. The level of genetic diversity in the present study population was very similar to that from Asian countries. A higher IgG response was found in the B-cell epitopes of msp-1 and csp antigens and higher level of antibodies against csp B-cell epitope and glurp antigen were recorded with increasing age groups. Significantly, higher positive responses were observed in the csp antigen among the samples with ≥42 NANP repeats. The present finding showed extensive diversity in the asexual stage antigens.
Collapse
Affiliation(s)
- Priyanka Patel
- National Institute for Research in Tribal Health, Indian Council of Medical Research, Garha, Jabalpur, Madhya Pradesh, India
| | - Praveen K. Bharti
- National Institute for Research in Tribal Health, Indian Council of Medical Research, Garha, Jabalpur, Madhya Pradesh, India
| | - Devendra Bansal
- Department of Microbiology and Immunology, Weill Cornell Medicine - Qatar, Cornell University, Qatar Foundation - Education City, Doha, Qatar
| | - Rajive K. Raman
- Community Health Centre Janakpur, District Baikunthpur, Chhattisgarh, India
| | - Pradyumna K. Mohapatra
- Regional Medical Research Centre, NE, Indian Council of Medical Research, Dibrugarh, Assam, India
| | - Rakesh Sehgal
- Department of Parasitology, Postgraduate Institute of Medical Education and Research, Chandigarh, Punjab, India
| | - Jagadish Mahanta
- Regional Medical Research Centre, NE, Indian Council of Medical Research, Dibrugarh, Assam, India
| | - Ali A. Sultan
- Department of Microbiology and Immunology, Weill Cornell Medicine - Qatar, Cornell University, Qatar Foundation - Education City, Doha, Qatar
| | - Neeru Singh
- National Institute for Research in Tribal Health, Indian Council of Medical Research, Garha, Jabalpur, Madhya Pradesh, India
- * E-mail:
| |
Collapse
|
22
|
Das SC, Morales RA, Seow J, Krishnarjuna B, Dissanayake R, Anders RF, MacRaild CA, Norton RS. Lipid interactions modulate the structural and antigenic properties of the C-terminal domain of the malaria antigen merozoite surface protein 2. FEBS J 2017; 284:2649-2662. [DOI: 10.1111/febs.14135] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 05/18/2017] [Accepted: 06/12/2017] [Indexed: 01/06/2023]
Affiliation(s)
- Sreedam C. Das
- Medicinal Chemistry; Monash Institute of Pharmaceutical Sciences; Monash University; Melbourne Australia
| | - Rodrigo A.V. Morales
- Medicinal Chemistry; Monash Institute of Pharmaceutical Sciences; Monash University; Melbourne Australia
| | - Jeffrey Seow
- Medicinal Chemistry; Monash Institute of Pharmaceutical Sciences; Monash University; Melbourne Australia
| | - Bankala Krishnarjuna
- Medicinal Chemistry; Monash Institute of Pharmaceutical Sciences; Monash University; Melbourne Australia
| | - Ravindu Dissanayake
- Department of Biochemistry and Genetics; La Trobe Institute for Molecular Science; La Trobe University; Melbourne Australia
| | - Robin F. Anders
- Department of Biochemistry and Genetics; La Trobe Institute for Molecular Science; La Trobe University; Melbourne Australia
| | - Christopher A. MacRaild
- Medicinal Chemistry; Monash Institute of Pharmaceutical Sciences; Monash University; Melbourne Australia
| | - Raymond S. Norton
- Medicinal Chemistry; Monash Institute of Pharmaceutical Sciences; Monash University; Melbourne Australia
| |
Collapse
|
23
|
Murungi LM, Sondén K, Odera D, Oduor LB, Guleid F, Nkumama IN, Otiende M, Kangoye DT, Fegan G, Färnert A, Marsh K, Osier FHA. Cord blood IgG and the risk of severe Plasmodium falciparum malaria in the first year of life. Int J Parasitol 2016; 47:153-162. [PMID: 27890694 PMCID: PMC5297353 DOI: 10.1016/j.ijpara.2016.09.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Revised: 08/31/2016] [Accepted: 09/03/2016] [Indexed: 01/18/2023]
Abstract
Severe malaria episodes are rare during the first few months of life. The rate of decay of cord blood IgG is inversely proportional to the starting concentration. Antibody dependent respiratory burst mediated by cord IgG protects from severe malaria during the first 6 months of infancy.
Young infants are less susceptible to severe episodes of malaria but the targets and mechanisms of protection are not clear. Cord blood antibodies may play an important role in mediating protection but many studies have examined their association with the outcome of infection or non-severe malaria. Here, we investigated whether cord blood IgG to Plasmodium falciparum merozoite antigens and antibody-mediated effector functions were associated with reduced odds of developing severe malaria at different time points during the first year of life. We conducted a case-control study of well-defined severe falciparum malaria nested within a longitudinal birth cohort of Kenyan children. We measured cord blood total IgG levels against five recombinant merozoite antigens and antibody function in the growth inhibition activity and neutrophil antibody-dependent respiratory burst assays. We also assessed the decay of maternal antibodies during the first 6 months of life. The mean antibody half-life range was 2.51 months (95% confidence interval (CI): 2.19–2.92) to 4.91 months (95% CI: 4.47–6.07). The rate of decline of maternal antibodies was inversely proportional to the starting concentration. The functional assay of antibody-dependent respiratory burst activity predicted significantly reduced odds of developing severe malaria during the first 6 months of life (Odds ratio (OR) 0.07, 95% CI: 0.007–0.74, P = 0.007). Identification of the targets of antibodies mediating antibody-dependent respiratory burst activity could contribute to the development of malaria vaccines that protect against severe episodes of malaria in early infancy.
Collapse
Affiliation(s)
- Linda M Murungi
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya.
| | - Klara Sondén
- Unit of Infectious Diseases, Department of Medicine, Solna, Karolinska Institutet, SE-171 76 Stockholm, Sweden
| | - Dennis Odera
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya
| | - Loureen B Oduor
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya
| | - Fatuma Guleid
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya
| | - Irene N Nkumama
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya
| | - Mark Otiende
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya
| | - David T Kangoye
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya; Centre National de Recherche et de Formation sur le Paludisme (CNRFP), 01 BP 2208, Ouagadougou 01, Burkina Faso
| | - Greg Fegan
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya
| | - Anna Färnert
- Unit of Infectious Diseases, Department of Medicine, Solna, Karolinska Institutet, SE-171 76 Stockholm, Sweden; Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Kevin Marsh
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya; African Academy of Sciences, P.O. Box 24916-00502, Nairobi, Kenya; Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom
| | - Faith H A Osier
- Kenya Medical Research Institute, Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya
| |
Collapse
|
24
|
Murungi LM, Sondén K, Llewellyn D, Rono J, Guleid F, Williams AR, Ogada E, Thairu A, Färnert A, Marsh K, Draper SJ, Osier FHA. Targets and Mechanisms Associated with Protection from Severe Plasmodium falciparum Malaria in Kenyan Children. Infect Immun 2016; 84:950-963. [PMID: 26787721 PMCID: PMC4807498 DOI: 10.1128/iai.01120-15] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 01/14/2016] [Indexed: 01/23/2023] Open
Abstract
Severe malaria (SM) is a life-threatening complication of infection with Plasmodium falciparum Epidemiological observations have long indicated that immunity against SM is acquired relatively rapidly, but prospective studies to investigate its immunological basis are logistically challenging and have rarely been undertaken. We investigated the merozoite targets and antibody-mediated mechanisms associated with protection against SM in Kenyan children aged 0 to 2 years. We designed a unique prospective matched case-control study of well-characterized SM clinical phenotypes nested within a longitudinal birth cohort of children (n= 5,949) monitored over the first 2 years of life. We quantified immunological parameters in sera collected before the SM event in cases and their individually matched controls to evaluate the prospective odds of developing SM in the first 2 years of life. Anti-AMA1 antibodies were associated with a significant reduction in the odds of developing SM (odds ratio [OR] = 0.37; 95% confidence interval [CI] = 0.15 to 0.90; P= 0.029) after adjustment for responses to all other merozoite antigens tested, while those against MSP-2, MSP-3, Plasmodium falciparum Rh2 [PfRh2], MSP-119, and the infected red blood cell surface antigens were not. The combined ability of total IgG to inhibit parasite growth and mediate the release of reactive oxygen species from neutrophils was associated with a marked reduction in the odds of developing SM (OR = 0.07; 95% CI = 0.006 to 0.82;P= 0.03). Assays of these two functional mechanisms were poorly correlated (Spearman rank correlation coefficient [rs] = 0.12;P= 0.07). Our data provide epidemiological evidence that multiple antibody-dependent mechanisms contribute to protective immunity via distinct targets whose identification could accelerate the development of vaccines to protect against SM.
Collapse
Affiliation(s)
- Linda M Murungi
- KEMRI Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya
| | - Klara Sondén
- Unit of Infectious Diseases, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden
| | - David Llewellyn
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Josea Rono
- KEMRI Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya
| | - Fatuma Guleid
- KEMRI Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya
| | | | - Edna Ogada
- KEMRI Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya
| | - Amos Thairu
- KEMRI Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya
| | - Anna Färnert
- Unit of Infectious Diseases, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden
| | - Kevin Marsh
- KEMRI Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya
- Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom
| | - Simon J Draper
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Faith H A Osier
- KEMRI Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya
| |
Collapse
|
25
|
Strain-transcending immune response generated by chimeras of the malaria vaccine candidate merozoite surface protein 2. Sci Rep 2016; 6:20613. [PMID: 26865062 PMCID: PMC4749986 DOI: 10.1038/srep20613] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 01/08/2016] [Indexed: 12/16/2022] Open
Abstract
MSP2 is an intrinsically disordered protein that is abundant on the merozoite surface and essential to the parasite Plasmodium falciparum. Naturally-acquired antibody responses to MSP2 are biased towards dimorphic sequences within the central variable region of MSP2 and have been linked to naturally-acquired protection from malaria. In a phase IIb study, an MSP2-containing vaccine induced an immune response that reduced parasitemias in a strain-specific manner. A subsequent phase I study of a vaccine that contained both dimorphic forms of MSP2 induced antibodies that exhibited functional activity in vitro. We have assessed the contribution of the conserved and variable regions of MSP2 to the generation of a strain-transcending antibody response by generating MSP2 chimeras that included conserved and variable regions of the 3D7 and FC27 alleles. Robust anti-MSP2 antibody responses targeting both conserved and variable regions were generated in mice, although the fine specificity and the balance of responses to these regions differed amongst the constructs tested. We observed significant differences in antibody subclass distribution in the responses to these chimeras. Our results suggest that chimeric MSP2 antigens can elicit a broad immune response suitable for protection against different strains of P. falciparum.
Collapse
|
26
|
Yman V, White MT, Rono J, Arcà B, Osier FH, Troye-Blomberg M, Boström S, Ronca R, Rooth I, Färnert A. Antibody acquisition models: A new tool for serological surveillance of malaria transmission intensity. Sci Rep 2016; 6:19472. [PMID: 26846726 PMCID: PMC4984902 DOI: 10.1038/srep19472] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 12/09/2015] [Indexed: 11/13/2022] Open
Abstract
Serology has become an increasingly important tool for the surveillance of a wide range of infectious diseases. It has been particularly useful to monitor malaria transmission in elimination settings where existing metrics such as parasite prevalence and incidence of clinical cases are less sensitive. Seroconversion rates, based on antibody prevalence to Plasmodium falciparum asexual blood-stage antigens, provide estimates of transmission intensity that correlate with entomological inoculation rates but lack precision in settings where seroprevalence is still high. Here we present a new and widely applicable method, based on cross-sectional data on individual antibody levels. We evaluate its use as a sero-surveillance tool in a Tanzanian setting with declining malaria prevalence. We find that the newly developed mathematical models produce more precise estimates of transmission patterns, are robust in high transmission settings and when sample sizes are small, and provide a powerful tool for serological evaluation of malaria transmission intensity.
Collapse
Affiliation(s)
- Victor Yman
- Unit of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden
| | - Michael T White
- MRC Centre for Outbreak Analysis &Modelling, Department of Infectious Disease Epidemiology, Imperial College, London, United Kingdom
| | - Josea Rono
- Unit of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.,KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya
| | - Bruno Arcà
- Department of Public Health and Infectious Diseases, Parasitology Section, Sapienza University of Rome, Italy
| | - Faith H Osier
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya
| | - Marita Troye-Blomberg
- Department of Molecular Biosciences, the Wenner-Gren Institute, Stockholm University, Sweden
| | - Stéphanie Boström
- Department of Molecular Biosciences, the Wenner-Gren Institute, Stockholm University, Sweden
| | - Raffaele Ronca
- Department of Biology, Federico II University, Naples, Italy
| | | | - Anna Färnert
- Unit of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden
| |
Collapse
|
27
|
Kangoye DT, Mensah VA, Murungi LM, Nkumama I, Nebie I, Marsh K, Cisse B, Bejon P, Osier FHA, Sirima SB. Dynamics and role of antibodies to Plasmodium falciparum merozoite antigens in children living in two settings with differing malaria transmission intensity. Vaccine 2015; 34:160-6. [PMID: 26541134 PMCID: PMC4683095 DOI: 10.1016/j.vaccine.2015.10.058] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 09/26/2015] [Accepted: 10/12/2015] [Indexed: 11/17/2022]
Abstract
BACKGROUND Young infants have reduced susceptibility to febrile malaria compared with older children, but the mechanism for this remains unclear. There are conflicting data on the role of passively acquired antibodies. Here, we examine antibody titres to merozoite surface antigens in the protection of children in their first two years of life in two settings with differing malaria transmission intensity and compare these titres to previously established protective thresholds. METHODS Two cohorts of children aged four to six weeks were recruited in Banfora, Burkina and Keur Soce, Senegal and followed up for two years. Malaria infections were detected by light microscopic examination of blood smears collected at active and passive case detection visits. The titres of antibodies to the Plasmodium falciparum recombinant merozoite proteins (AMA1-3D7, MSP1-19, MSP2-Dd2, and MSP3-3D7) were measured by enzyme-linked immunosorbent assay at 1-6, 9, 12, 15 and 18 months of age and compared with the protective thresholds established in Kenyan children. RESULTS Antibody titres were below the protective thresholds throughout the study period and we did not find any association with protection against febrile malaria. Antibodies to AMA1 and MSP1-19 appeared to be markers of exposure in the univariate analysis (and so associated with increasing risk) and adjusting for exposure reduced the strength and significance of this association. CONCLUSION The antibody levels we measured are unlikely to be responsible for the apparent protection against febrile malaria seen in young infants. Further work to identify protective antibody responses might include functional assays and a wider range of antigens.
Collapse
Affiliation(s)
- David Tiga Kangoye
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), 01 BP 2208, Ouagadougou 01, Burkina Faso; Kenya Medical Research Institute, Centre for Geographic Medicine Research Coast (KEMRI-CGMRC), P.O. Box 230, Kilifi 80108, Kenya.
| | | | - Linda Muthoni Murungi
- Kenya Medical Research Institute, Centre for Geographic Medicine Research Coast (KEMRI-CGMRC), P.O. Box 230, Kilifi 80108, Kenya
| | - Irene Nkumama
- Kenya Medical Research Institute, Centre for Geographic Medicine Research Coast (KEMRI-CGMRC), P.O. Box 230, Kilifi 80108, Kenya
| | - Issa Nebie
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), 01 BP 2208, Ouagadougou 01, Burkina Faso
| | - Kevin Marsh
- Kenya Medical Research Institute, Centre for Geographic Medicine Research Coast (KEMRI-CGMRC), P.O. Box 230, Kilifi 80108, Kenya; Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom
| | - Badara Cisse
- Service de Parasitologie, Université Cheikh Anta Diop (UCAD), BP 5005 UCAD, Dakar, Senegal
| | - Philip Bejon
- Kenya Medical Research Institute, Centre for Geographic Medicine Research Coast (KEMRI-CGMRC), P.O. Box 230, Kilifi 80108, Kenya; Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Churchill Hospital, Oxford, United Kingdom
| | - Faith Hope Among'in Osier
- Kenya Medical Research Institute, Centre for Geographic Medicine Research Coast (KEMRI-CGMRC), P.O. Box 230, Kilifi 80108, Kenya
| | - Sodiomon Bienvenu Sirima
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), 01 BP 2208, Ouagadougou 01, Burkina Faso
| |
Collapse
|
28
|
Sack BK, Keitany GJ, Vaughan AM, Miller JL, Wang R, Kappe SHI. Mechanisms of stage-transcending protection following immunization of mice with late liver stage-arresting genetically attenuated malaria parasites. PLoS Pathog 2015; 11:e1004855. [PMID: 25974076 PMCID: PMC4431720 DOI: 10.1371/journal.ppat.1004855] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Accepted: 04/06/2015] [Indexed: 11/19/2022] Open
Abstract
Malaria, caused by Plasmodium parasite infection, continues to be one of the leading causes of worldwide morbidity and mortality. Development of an effective vaccine has been encumbered by the complex life cycle of the parasite that has distinct pre-erythrocytic and erythrocytic stages of infection in the mammalian host. Historically, malaria vaccine development efforts have targeted each stage in isolation. An ideal vaccine, however, would target multiple life cycle stages with multiple arms of the immune system and be capable of eliminating initial infection in the liver, the subsequent blood stage infection, and would prevent further parasite transmission. We have previously shown that immunization of mice with Plasmodium yoelii genetically attenuated parasites (GAP) that arrest late in liver stage development elicits stage-transcending protection against both a sporozoite challenge and a direct blood stage challenge. Here, we show that this immunization strategy engenders both T- and B-cell responses that are essential for stage-transcending protection, but the relative importance of each is determined by the host genetic background. Furthermore, potent anti-blood stage antibodies elicited after GAP immunization rely heavily on FC-mediated functions including complement fixation and FC receptor binding. These protective antibodies recognize the merozoite surface but do not appear to recognize the immunodominant merozoite surface protein-1. The antigen(s) targeted by stage-transcending immunity are present in both the late liver stages and blood stage parasites. The data clearly show that GAP-engendered protective immune responses can target shared antigens of pre-erythrocytic and erythrocytic parasite life cycle stages. As such, this model constitutes a powerful tool to identify novel, protective and stage-transcending T and B cell targets for incorporation into a multi-stage subunit vaccine.
Collapse
Affiliation(s)
- Brandon K. Sack
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Gladys J. Keitany
- Department of Immunology, University of Washington, Seattle, Washington, United States of America
| | - Ashley M. Vaughan
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Jessica L. Miller
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Ruobing Wang
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Stefan H. I. Kappe
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
- * E-mail:
| |
Collapse
|
29
|
Rono J, Färnert A, Murungi L, Ojal J, Kamuyu G, Guleid F, Nyangweso G, Wambua J, Kitsao B, Olotu A, Marsh K, Osier FH. Multiple clinical episodes of Plasmodium falciparum malaria in a low transmission intensity setting: exposure versus immunity. BMC Med 2015; 13:114. [PMID: 25967134 PMCID: PMC4445794 DOI: 10.1186/s12916-015-0354-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Accepted: 04/27/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Epidemiological studies indicate that some children experience many more episodes of clinical malaria than their age mates in a given location. Whether this is as a result of the micro-heterogeneity of malaria transmission with some children effectively getting more exposure to infectious mosquitoes than others, or reflects a failure in the acquisition of immunity needs to be elucidated. Here, we investigated the determinants of increased susceptibility to clinical malaria by comparing the intensity of exposure to Plasmodium falciparum and the acquisition of immunity in children at the extreme ends of the over-dispersed distribution of the incidence of clinical malaria. METHODS The study was nested within a larger cohort in an area where the intensity of malaria transmission was low. We identified children who over a five-year period experienced 5 to 16 clinical malaria episodes (children at the tail-end of the over-dispersed distribution, n = 35), remained malaria-free (n = 12) or had a single episode (n = 26). We quantified antibodies against seven Plasmodium falciparum merozoite antigens in plasma obtained at six cross-sectional surveys spanning these five years. We analyzed the antibody responses to identify temporal dynamics that associate with disease susceptibility. RESULTS Children experiencing multiple episodes of malaria were more likely to be parasite positive by microscopy at cross-sectional surveys (X (2) test for trend 14.72 P = 0.001) and had a significantly higher malaria exposure index, than those in the malaria-free or single episode groups (Kruskal-Wallis test P = 0.009). In contrast, the five-year temporal dynamics of anti-merozoite antibodies were similar in the three groups. Importantly in all groups, antibody levels were below the threshold concentrations previously observed to be correlated with protective immunity. CONCLUSIONS We conclude that in the context of a low malaria transmission setting, susceptibility to clinical malaria is not accounted for by anti-merozoite antibodies but appears to be a consequence of increased parasite exposure. We hypothesize that intensive exposure is a prerequisite for protective antibody concentrations, while little to modest exposure may manifest as multiple clinical infections with low levels of antibodies. These findings have implications for interventions that effectively lower malaria transmission intensity.
Collapse
Affiliation(s)
- Josea Rono
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
- Infectious Diseases Unit, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden.
| | - Anna Färnert
- Infectious Diseases Unit, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden.
| | - Linda Murungi
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
| | - John Ojal
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
| | - Gathoni Kamuyu
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
| | - Fatuma Guleid
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
| | - George Nyangweso
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
| | - Juliana Wambua
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
| | - Barnes Kitsao
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
| | - Ally Olotu
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
| | - Kevin Marsh
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
- Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, University of Oxford, Oxford, UK.
| | - Faith Ha Osier
- KEMRI-Wellcome Trust Research Programme, Centre for Geographical Medicine Research-Coast, Kilifi, Kenya.
| |
Collapse
|
30
|
Structural basis for epitope masking and strain specificity of a conserved epitope in an intrinsically disordered malaria vaccine candidate. Sci Rep 2015; 5:10103. [PMID: 25965408 PMCID: PMC4428071 DOI: 10.1038/srep10103] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 03/30/2015] [Indexed: 12/15/2022] Open
Abstract
Merozoite surface protein 2 (MSP2) is an intrinsically disordered, membrane-anchored antigen of the malaria parasite Plasmodium falciparum. MSP2 can elicit a protective, albeit strain-specific, antibody response in humans. Antibodies are generated to the conserved N- and C-terminal regions but many of these react poorly with the native antigen on the parasite surface. Here we demonstrate that recognition of a conserved N-terminal epitope by mAb 6D8 is incompatible with the membrane-bound conformation of that region, suggesting a mechanism by which native MSP2 escapes antibody recognition. Furthermore, crystal structures and NMR spectroscopy identify transient, strain-specific interactions between the 6D8 antibody and regions of MSP2 beyond the conserved epitope. These interactions account for the differential affinity of 6D8 for the two allelic families of MSP2, even though 6D8 binds to a fully conserved epitope. These results highlight unappreciated mechanisms that may modulate the specificity and efficacy of immune responses towards disordered antigens.
Collapse
|
31
|
Cheng Y, Li J, Ito D, Kong DH, Ha KS, Lu F, Wang B, Sattabongkot J, Lim CS, Tsuboi T, Han ET. Antigenicity and immunogenicity of PvRALP1, a novel Plasmodium vivax rhoptry neck protein. Malar J 2015; 14:186. [PMID: 25925592 PMCID: PMC4435652 DOI: 10.1186/s12936-015-0698-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 04/12/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Proteins secreted from the rhoptry in Plasmodium merozoites are associated with the formation of tight junctions and parasitophorous vacuoles during invasion of erythrocytes and are sorted within the rhoptry neck or bulb. Very little information has been obtained to date about Plasmodium vivax rhoptry-associated leucine (Leu) zipper-like protein 1 (PvRALP1; PVX_096245), a putative rhoptry protein. PvRALP1 contains a signal peptide, a glycine (Gly)/glutamate (Glu)-rich domain, and a Leu-rich domain, all of which are conserved in other Plasmodium species. METHODS Recombinant PvRALP1s were expressed as full-length protein without the signal peptide (PvRALP1-Ecto) and as truncated protein consisting of the Gly/Glu- and Leu-rich domains (PvRALP1-Tr) using the wheat germ cell-free expression system. The immunoreactivity to these two fragments of recombinant PvRALP1 protein in serum samples from P. vivax-infected patients and immunized mice, including analysis of immunoglobulin G (IgG) subclasses, was evaluated by enzyme-linked immunosorbent assay or protein microarray technology. The subcellular localization of PvRALP1 in blood stage parasites was also determined. RESULTS Recombinant PvRALP1-Ecto and PvRALP1-Tr proteins were successfully expressed, and in serum samples from P. vivax patients from the Republic of Korea, the observed immunoreactivities to these proteins had 58.9% and 55.4% sensitivity and 95.0% and 92.5% specificity, respectively. The response to PvRALP1 in humans was predominantly cytophilic antibodies (IgG1 and IgG3), but a balanced Th1/Th2 response was observed in mice. Unexpectedly, there was no significant inverse correlation between levels of parasitaemia and levels of antibody against either PvRALP1-Ecto (R2=0.11) or PvRALP1-Tr (R2=0.14) antigens. PvRALP1 was localized in the rhoptry neck of merozoites, and this was the first demonstration of the localization of this protein in P. vivax. CONCLUSIONS This study analysed the antigenicity and immunogenicity of PvRALP1 and suggested that PvRALP1 may be immunogenic in humans during parasite infection and might play an important role during invasion of P. vivax parasites.
Collapse
Affiliation(s)
- Yang Cheng
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Hyoja2-dong, Chuncheon, Gangwon-do, 200-701, Republic of Korea. .,Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Rockville, MD, 20852, USA.
| | - Jian Li
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Hyoja2-dong, Chuncheon, Gangwon-do, 200-701, Republic of Korea. .,Department of Parasitology, College of Basic Medicine, Hubei University of Medicine, Hubei, 442000, China.
| | - Daisuke Ito
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Rockville, MD, 20852, USA. .,Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime, 790-8577, Japan.
| | - Deok-Hoon Kong
- Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, 200-701, Republic of Korea.
| | - Kwon-Soo Ha
- Department of Molecular and Cellular Biochemistry, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, 200-701, Republic of Korea.
| | - Feng Lu
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Hyoja2-dong, Chuncheon, Gangwon-do, 200-701, Republic of Korea. .,Key Laboratory of Parasitic Disease Control and Prevention (Ministry of Health), and Jiangsu Provincial Key Laboratory of Parasite Molecular Biology, Jiangsu Institute of Parasitic Diseases, Wuxi, Jiangsu Province, People's Republic of China.
| | - Bo Wang
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Hyoja2-dong, Chuncheon, Gangwon-do, 200-701, Republic of Korea. .,Department of Clinical Laboratory, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, People's Republic of China.
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand.
| | - Chae Seung Lim
- Department of Laboratory Medicine, College of Medicine, Korea University Guro Hospital, Seoul, 152-703, Republic of Korea.
| | - Takafumi Tsuboi
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime, 790-8577, Japan.
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, Kangwon National University School of Medicine, Hyoja2-dong, Chuncheon, Gangwon-do, 200-701, Republic of Korea.
| |
Collapse
|
32
|
MacRaild CA, Zachrdla M, Andrew D, Krishnarjuna B, Nováček J, Žídek L, Sklenář V, Richards JS, Beeson JG, Anders RF, Norton RS. Conformational dynamics and antigenicity in the disordered malaria antigen merozoite surface protein 2. PLoS One 2015; 10:e0119899. [PMID: 25742002 PMCID: PMC4351039 DOI: 10.1371/journal.pone.0119899] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 01/16/2015] [Indexed: 12/14/2022] Open
Abstract
Merozoite surface protein 2 (MSP2) of Plasmodium falciparum is an abundant, intrinsically disordered protein that is GPI-anchored to the surface of the invasive blood stage of the malaria parasite. Recombinant MSP2 has been trialled as a component of a malaria vaccine, and is one of several disordered proteins that are candidates for inclusion in vaccines for malaria and other diseases. Nonetheless, little is known about the implications of protein disorder for the development of an effective antibody response. We have therefore undertaken a detailed analysis of the conformational dynamics of the two allelic forms of MSP2 (3D7 and FC27) using NMR spectroscopy. Chemical shifts and NMR relaxation data indicate that conformational and dynamic properties of the N- and C-terminal conserved regions in the two forms of MSP2 are essentially identical, but significant variation exists between and within the central variable regions. We observe a strong relationship between the conformational dynamics and the antigenicity of MSP2, as assessed with antisera to recombinant MSP2. Regions of increased conformational order in MSP2, including those in the conserved regions, are more strongly antigenic, while the most flexible regions are minimally antigenic. This suggests that modifications that increase conformational order may offer a means to tune the antigenicity of MSP2 and other disordered antigens, with implications for vaccine design.
Collapse
Affiliation(s)
- Christopher A. MacRaild
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, 3052, Australia
- * E-mail:
| | - Milan Zachrdla
- NCBR, Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
- CEITEC, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
| | - Dean Andrew
- Centre for Biomedical Research, Burnet Institute, Melbourne, Victoria, 3004, Australia
| | - Bankala Krishnarjuna
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, 3052, Australia
| | - Jiří Nováček
- NCBR, Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
- CEITEC, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
| | - Lukáš Žídek
- NCBR, Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
- CEITEC, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
| | - Vladimír Sklenář
- NCBR, Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
- CEITEC, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
| | - Jack S. Richards
- Centre for Biomedical Research, Burnet Institute, Melbourne, Victoria, 3004, Australia
| | - James G. Beeson
- Centre for Biomedical Research, Burnet Institute, Melbourne, Victoria, 3004, Australia
| | - Robin F. Anders
- Department of Biochemistry, La Trobe University, Victoria, 3086, Australia
| | - Raymond S. Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, 3052, Australia
| |
Collapse
|
33
|
Cherif MK, Sanou GS, Bougouma EC, Diarra A, Ouédraogo A, Dolo A, Troye-Blomberg M, Cavanagh DR, Theisen M, Modiano D, Sirima SB, Nebié I. Is Fc gamma receptor IIA (FcγRIIA) polymorphism associated with clinical malaria and Plasmodium falciparum specific antibody levels in children from Burkina Faso? Acta Trop 2015; 142:41-6. [PMID: 25447268 DOI: 10.1016/j.actatropica.2014.09.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 09/26/2014] [Accepted: 09/29/2014] [Indexed: 11/18/2022]
Abstract
In the present study, the influences of FcγRIIA polymorphism on susceptibility to malaria and antibody responses to Plasmodium falciparum antigens were analyzed in children. We recruited 96 healthy children between 3 and 10 years at the beginning of the high transmission season and we followed up for 5 months through the high transmission season to assess the parasitological, immunological and genetic endpoints in relation to clinical malaria status. There was a similar distribution of homozygous and heterozygous individuals carrying the FcγRIIA-131R/R and FcγRIIA-131R/H allele, whereas the number of FcγRIIA-131H/H homozygous individuals was lower. P. falciparum infection frequency was not associated with the FcγRIIa-131R/H polymorphism. Only IgG antibody responses to GLURP R0 showed a significant association between antibody levels and FcγRIIA polymorphism (p=0.02). IgG levels to MSP2a were significantly higher in children who did not experience any clinical malaria episode compared to those who experienced at least one malaria episode (p=0.019). Cytophilic and non-cytophylic IgG subclass levels were higher in children without malaria than those who experienced at least one malaria episode. This difference was statistically significant for IgG1 to MSP3 (p=0.003) and to MSP2a (p=0.006); IgG3 to MSP2a (p=0.007) and to GLURP R0 (p=0.044); IgG2 to MSP2b (p=0.007) and IgG4 to MSP3 (p=0.051) and to MSP2a (p=0.049). In this study, homozygous carriers of the FcγRIIA-131R/R allele had higher malaria-specific antibody levels compare to the heterozygous carriers FcγRIIA-131R/H alleles and to homozygous carriers of FcγRIIA-131H/H alleles. The pre-existing antibodies responses were related to a reduced subsequent risk of clinical malaria.
Collapse
Affiliation(s)
- Mariama K Cherif
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso; Université de Ouagadougou, Burkina Faso
| | - Guillaume S Sanou
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso; Polytechnic University of Bobo Dioulasso, Burkina Faso
| | - Edith C Bougouma
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Amidou Diarra
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Alphonse Ouédraogo
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Amagana Dolo
- Malaria Research and Training Centre, University of Mali, Bamako, Mali
| | | | - David R Cavanagh
- Institute of Immunology and Infection Research, University of Edinburgh, EH9 3JT, Scotland, United Kingdom
| | - Michael Theisen
- Department of Clinical Biochemistry and Immunology, Statens Serum Institut, Copenhagen, Denmark; Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, department of Infectious Diseases, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - David Modiano
- Department of Public Health Sciences, University La Sapienza, Rome, Italy
| | - Sodiomon B Sirima
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Issa Nebié
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso.
| |
Collapse
|
34
|
Balam S, Olugbile S, Servis C, Diakité M, D'Alessandro A, Frank G, Moret R, Nebie I, Tanner M, Felger I, Smith T, Kajava AV, Spertini F, Corradin G. Plasmodium falciparum merozoite surface protein 2: epitope mapping and fine specificity of human antibody response against non-polymorphic domains. Malar J 2014; 13:510. [PMID: 25526742 PMCID: PMC4320585 DOI: 10.1186/1475-2875-13-510] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 12/06/2014] [Indexed: 11/16/2022] Open
Abstract
Background Two long synthetic peptides representing the dimorphic and constant C-terminal domains of the two allelic families of Plasmodium falciparum merozoite surface proteins 2 are considered promising malaria vaccine candidates. The aim of the current study is to characterize the immune response (epitope mapping) in naturally exposed individuals and relate immune responses to the risk of clinical malaria. Methods To optimize their construction, the fine specificity of human serum antibodies from donors of different age, sex and living in four distinct endemic regions was determined in ELISA by using overlapping 20 mer peptides covering the two domains. Immune purified antibodies were used in Western blot and immunofluorescence assay to recognize native parasite derivate proteins. Results Immunodominant epitopes were characterized, and their distribution was similar irrespective of geographic origin, age group and gender. Acquisition of a 3D7 family and constant region-specific immune response and antibody avidity maturation occur early in life while a longer period is needed for the corresponding FC27 family response. In addition, the antibody response to individual epitopes within the 3D7 family-specific region contributes to protection from malaria infection with different statistical weight. It is also illustrated that affinity-purified antibodies against the dimorphic or constant regions recognized homologous and heterologous parasites in immunofluorescence and homologous and heterologous MSP2 and other polypeptides in Western blot. Conclusion Data from this current study may contribute to a development of MSP2 vaccine candidates based on conserved and dimorphic regions thus bypassing the complexity of vaccine development related to the polymorphism of full-length MSP2. Electronic supplementary material The online version of this article (doi:10.1186/1475-2875-13-510) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Saidou Balam
- Department of Biochemistry, University of Lausanne, Ch des Boveresses 155, 1066 Epalinges, Switzerland.
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Acquisition of antibodies against Plasmodium falciparum merozoites and malaria immunity in young children and the influence of age, force of infection, and magnitude of response. Infect Immun 2014; 83:646-60. [PMID: 25422270 DOI: 10.1128/iai.02398-14] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Individuals in areas of Plasmodium falciparum endemicity develop immunity to malaria after repeated exposure. Knowledge of the acquisition and nature of protective immune responses to P. falciparum is presently limited, particularly for young children. We examined antibodies (IgM, IgG, and IgG subclasses) to merozoite antigens and their relationship to the prospective risk of malaria in children 1 to 4 years of age in a region of malaria endemicity in Papua New Guinea. IgG, IgG1, and IgG3 responses generally increased with age, were higher in children with active infection, and reflected geographic heterogeneity in malaria transmission. Antigenic properties, rather than host factors, appeared to be the main determinant of the type of IgG subclass produced. High antibody levels were not associated with protection from malaria; in contrast, they were typically associated with an increased risk of malaria. Adjustment for malaria exposure, using a novel molecular measure of the force of infection by P. falciparum, accounted for much of the increased risk, suggesting that the antibodies were markers of higher exposure to P. falciparum. Comparisons between antibodies in this cohort of young children and in a longitudinal cohort of older children suggested that the lack of protective association was explained by lower antibody levels among young children and that there is a threshold level of antibodies required for protection from malaria. Our results suggest that in populations with low immunity, such as young children, antibodies to merozoite antigens may act as biomarkers of malaria exposure and that, with increasing exposure and responses of higher magnitude, antibodies may act as biomarkers of protective immunity.
Collapse
|
36
|
Roy SW, Ferreira MU. A new model for the origins of allelic dimorphism in Plasmodium falciparum. Parasitol Int 2014; 64:229-37. [PMID: 25251164 DOI: 10.1016/j.parint.2014.09.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 07/11/2014] [Accepted: 09/12/2014] [Indexed: 11/17/2022]
Abstract
In his landmark 1987 study of the merozoite surface protein-1 locus in Plasmodium falciparum, Kazuyuki Tanabe and coauthors introduced the phenomenon of allelic dimorphism, in which antigenic diversity is arranged into two maximally diverged haplotypes. Further work has extended this finding to other loci in P. falciparum. Each of the loci at which allelic dimorphism is observed encodes major surface antigens of blood-stage malaria parasites, and is consequently a major vaccine target, thus understanding the origins and implications of allelic dimorphism is of crucial importance. Here we examine the essential features of allelic dimorphism in dimorphic malarial surface antigens. From sequence analysis, we conclude that the ancestral population may have been recombining/multimorphic rather than dimorphic. We hypothesize a pathway to allelic dimorphism in which an ancestral allele-rich recombining population could have undergone a severe population bottleneck, putatively caused by the lateral transfer of P. falciparum from apes to humans. This bottleneck produced a reduction in allelic diversity, favoring the survival of the most divergent alleles, which in turn led to recombination suppression by strong natural selection against recombinants.
Collapse
Affiliation(s)
- Scott W Roy
- Department of Biology, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA.
| | - Marcelo U Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, 05508-900 São Paulo, SP, Brazil.
| |
Collapse
|
37
|
Osier FH, Mackinnon MJ, Crosnier C, Fegan G, Kamuyu G, Wanaguru M, Ogada E, McDade B, Rayner JC, Wright GJ, Marsh K. New antigens for a multicomponent blood-stage malaria vaccine. Sci Transl Med 2014; 6:247ra102. [PMID: 25080477 PMCID: PMC4856877 DOI: 10.1126/scitranslmed.3008705] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
An effective blood-stage vaccine against Plasmodium falciparum remains a research priority, but the number of antigens that have been translated into multicomponent vaccines for testing in clinical trials remains limited. Investigating the large number of potential targets found in the parasite proteome has been constrained by an inability to produce natively folded recombinant antigens for immunological studies. We overcame these constraints by generating a large library of biochemically active merozoite surface and secreted full-length ectodomain proteins. We then systematically examined the antibody reactivity against these proteins in a cohort of Kenyan children (n = 286) who were sampled at the start of a malaria transmission season and prospectively monitored for clinical episodes of malaria over the ensuing 6 months. We found that antibodies to previously untested or little-studied proteins had superior or equivalent potential protective efficacy to the handful of current leading malaria vaccine candidates. Moreover, cumulative responses to combinations comprising 5 of the 10 top-ranked antigens, including PF3D7_1136200, MSP2, RhopH3, P41, MSP11, MSP3, PF3D7_0606800, AMA1, Pf113, and MSRP1, were associated with 100% protection against clinical episodes of malaria. These data suggest not only that there are many more potential antigen candidates for the malaria vaccine development pipeline but also that effective vaccination may be achieved by combining a selection of these antigens.
Collapse
MESH Headings
- Age Factors
- Antibodies, Protozoan/blood
- Antigens, Protozoan/immunology
- Biomarkers/blood
- Child
- Child, Preschool
- Humans
- Infant
- Infant, Newborn
- Kenya/epidemiology
- Malaria Vaccines/immunology
- Malaria, Falciparum/blood
- Malaria, Falciparum/epidemiology
- Malaria, Falciparum/immunology
- Malaria, Falciparum/parasitology
- Malaria, Falciparum/prevention & control
- Malaria, Falciparum/transmission
- Merozoites/immunology
- Peptide Fragments/immunology
- Plasmodium falciparum/immunology
- Prospective Studies
- Protozoan Proteins/immunology
- Seroepidemiologic Studies
- Time Factors
Collapse
Affiliation(s)
- Faith H Osier
- Pathogen Vector and Human Biology Department, Kenya Medical Research Institute Centre for Geographical Medicine Research, Coast, P. O. Box 230, 80108 Kilifi, Kenya
| | - Margaret J Mackinnon
- Pathogen Vector and Human Biology Department, Kenya Medical Research Institute Centre for Geographical Medicine Research, Coast, P. O. Box 230, 80108 Kilifi, Kenya
| | - Cécile Crosnier
- Cell Surface Signalling Laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1HH, UK. Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, UK
| | - Gregory Fegan
- Pathogen Vector and Human Biology Department, Kenya Medical Research Institute Centre for Geographical Medicine Research, Coast, P. O. Box 230, 80108 Kilifi, Kenya
| | - Gathoni Kamuyu
- Pathogen Vector and Human Biology Department, Kenya Medical Research Institute Centre for Geographical Medicine Research, Coast, P. O. Box 230, 80108 Kilifi, Kenya
| | - Madushi Wanaguru
- Cell Surface Signalling Laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1HH, UK. Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, UK
| | - Edna Ogada
- Pathogen Vector and Human Biology Department, Kenya Medical Research Institute Centre for Geographical Medicine Research, Coast, P. O. Box 230, 80108 Kilifi, Kenya
| | - Brian McDade
- Cell Surface Signalling Laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1HH, UK
| | - Julian C Rayner
- Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, UK
| | - Gavin J Wright
- Cell Surface Signalling Laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1HH, UK. Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, UK
| | - Kevin Marsh
- Pathogen Vector and Human Biology Department, Kenya Medical Research Institute Centre for Geographical Medicine Research, Coast, P. O. Box 230, 80108 Kilifi, Kenya.
| |
Collapse
|
38
|
Barry AE, Arnott A. Strategies for designing and monitoring malaria vaccines targeting diverse antigens. Front Immunol 2014; 5:359. [PMID: 25120545 PMCID: PMC4112938 DOI: 10.3389/fimmu.2014.00359] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 07/13/2014] [Indexed: 01/28/2023] Open
Abstract
After more than 50 years of intensive research and development, only one malaria vaccine candidate, “RTS,S,” has progressed to Phase 3 clinical trials. Despite only partial efficacy, this candidate is now forecast to become the first licensed malaria vaccine. Hence, more efficacious second-generation malaria vaccines that can significantly reduce transmission are urgently needed. This review will focus on a major obstacle hindering development of effective malaria vaccines: parasite antigenic diversity. Despite extensive genetic diversity in leading candidate antigens, vaccines have been and continue to be formulated using recombinant antigens representing only one or two strains. These vaccine strains represent only a small fraction of the diversity circulating in natural parasite populations, leading to escape of non-vaccine strains and challenging investigators’ abilities to measure strain-specific efficacy in vaccine trials. Novel strategies are needed to overcome antigenic diversity in order for vaccine development to succeed. Many studies have now cataloged the global diversity of leading Plasmodium falciparum and Plasmodium vivax vaccine antigens. In this review, we describe how population genetic approaches can be applied to this rich data source to predict the alleles that best represent antigenic diversity, polymorphisms that contribute to it, and to identify key polymorphisms associated with antigenic escape. We also suggest an approach to summarize the known global diversity of a given antigen to predict antigenic diversity, how to select variants that best represent the strains circulating in natural parasite populations and how to investigate the strain-specific efficacy of vaccine trials. Use of these strategies in the design and monitoring of vaccine trials will not only shed light on the contribution of genetic diversity to the antigenic diversity of malaria, but will also maximize the potential of future malaria vaccine candidates.
Collapse
Affiliation(s)
- Alyssa E Barry
- Division of Infection and Immunity, Walter and Eliza Hall Institute of Medical Research , Parkville, VIC , Australia ; Department of Medical Biology, The University of Melbourne , Parkville, VIC , Australia
| | - Alicia Arnott
- Division of Infection and Immunity, Walter and Eliza Hall Institute of Medical Research , Parkville, VIC , Australia ; Department of Medical Biology, The University of Melbourne , Parkville, VIC , Australia
| |
Collapse
|
39
|
Diop F, Richard V, Diouf B, Sokhna C, Diagne N, Trape JF, Faye MM, Tall A, Diop G, Balde AT. Dramatic declines in seropositivity as determined with crude extracts of Plasmodium falciparum schizonts between 2000 and 2010 in Dielmo and Ndiop, Senegal. Malar J 2014; 13:83. [PMID: 24602390 PMCID: PMC3975713 DOI: 10.1186/1475-2875-13-83] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 02/26/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Programmes of pre-elimination of malaria have been implemented in Senegal since 2010, and the burden of malaria has decreased substantially. These changes in the epidemiology should be monitored with effective tools that allow changes in patterns of transmission to be estimated. In Dielmo and Ndiop, two villages of Senegal with different malaria endemicity, infections have been followed longitudinally for 20 years, during which time there have been several control interventions leading to substantial decreases of transmission. This study aimed to compare malaria antibody responses of the inhabitants of these two villages, between 2000 and 2010, using schizont crude extracts of a local strain of P. falciparum (Pf Sch07/03). METHODS Sera collected from inhabitants of the two villages (141 from Dielmo and 79 from Ndiop in 2000; 143 from Dielmo and 79 from Ndiop in 2010) were used to assess the prevalence of antibodies against crude schizont extracts of Pf Sch07/03. Three ages groups were defined: [5-9] yrs, [10-14] yrs and [15-19] yrs. Statistical comparisons were performed. Seroprevalence and the magnitude of antibody responses were compared between age groups, villages and periods. RESULTS Overall seroprevalence to P.fSch07/03 decreased between 2000 and 2010 in both villages: from 94.4% to 44.4% in Dielmo and from 74.4% to 34.6% in Ndiop. The difference between Dielmo and Ndiop was highly significant in 2000 (p<0.001) but not in 2010 (p >0.20). The decrease in seroprevalence was larger in younger (more than 40%) than older (less than 19%) inhabitants. Longitudinal monitoring of the younger group showed that seroprevalence decreased between 2000 and 2010 in Dielmo from 98.7 to 79.3, but not in Ndiop from 67.6 to 66.7. The magnitude of antibody responses in seropositive individuals was significantly higher in 2000 than 2010 for both villages. CONCLUSIONS Crude extracts of P. falciparum are appropriate tools for evaluating malaria prevalence at different periods, and in both low and high endemic area. Using crude extracts from local strains to assess transmission may allow efficient evaluation of the consequences of control programs on malaria transmission.
Collapse
|
40
|
Wilmore JR, Maue AC, Lefebvre JS, Haynes L, Rochford R. AcutePlasmodium chabaudiInfection Dampens Humoral Responses to a Secondary T-Dependent Antigen but Enhances Responses to a Secondary T-Independent Antigen. THE JOURNAL OF IMMUNOLOGY 2013; 191:4731-9. [DOI: 10.4049/jimmunol.1301450] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
|
41
|
Rono J, Osier FHA, Olsson D, Montgomery S, Mhoja L, Rooth I, Marsh K, Färnert A. Breadth of anti-merozoite antibody responses is associated with the genetic diversity of asymptomatic Plasmodium falciparum infections and protection against clinical malaria. Clin Infect Dis 2013; 57:1409-16. [PMID: 23983244 DOI: 10.1093/cid/cit556] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Elucidating the mechanisms of naturally acquired immunity to Plasmodium falciparum infections would be highly valuable for malaria vaccine development. Asymptomatic multiclonal infections have been shown to predict protection from clinical malaria in a transmission-dependent manner, but the mechanisms underlying this are unclear. We assessed the breadth of antibody responses to several vaccine candidate merozoite antigens in relation to the infecting parasite population and clinical immunity. METHODS In a cohort study in Tanzania, 320 children aged 1-16 years who were asymptomatic at baseline were included. We genotyped P. falciparum infections by targeting the msp2 gene using polymerase chain reaction and capillary electrophoresis and measured antibodies to 7 merozoite antigens using a multiplex assay. We assessed the correlation between the number of clones and the breadth of the antibody response, and examined their effects on the risk of malaria during 40 weeks of follow-up using age-adjusted multivariate regression models. RESULTS The antibody breadth was positively correlated with the number of clones (RR [risk ratio], 1.63; 95% confidence interval [CI], 1.32-2.02). Multiclonal infections were associated with a nonsignificant reduction in the risk of malaria in the absence of antibodies (RR, 0.83; 95% CI, .29-2.34). The breadth of the antibody response was significantly associated with a reduced risk of malaria in the absence of infections (RR, 0.25; 95% CI, .09-.66). In combination, these factors were associated with a lower risk of malaria than they were individually (RR, 0.14; 95% CI, .04-.48). CONCLUSIONS These data suggest that malaria vaccines mimicking naturally acquired immunity should ideally induce antibody responses that can be boosted by natural infections.
Collapse
Affiliation(s)
- Josea Rono
- Infectious Diseases Unit, Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden
| | | | | | | | | | | | | | | |
Collapse
|
42
|
Khosravi A, Asadollahy E, Ghafourian S, Sadeghifard N, Mohebi R. Synthesis and evaluation of monoclonal antibody against Plasmodium falciparum merozoite surface antigen 2. ASIAN PAC J TROP MED 2013; 6:798-803. [PMID: 23870469 DOI: 10.1016/s1995-7645(13)60141-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Revised: 06/15/2013] [Accepted: 07/15/2013] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE To assess the quality of expressed MSP-2 and also to confirm the immune response against different domains of these proteins. METHODS Mice were immunized with a schizont extract to stimulate the immune system to make antibodies against different antigens of the late stage parasite including production of antibodies against different domains of Plasmodium falciparum (P. falciparum) MSP-2. B lymphocytes of immunized mice were extracted from the spleen and the fusion was performed using NS-1 myeloma cells and the hybridoma cells were assayed by ELISA either with a schizont extract or different domains of MSP-2 and/or by IFAT with whole schizont preparation. Fusion of NS-1 and spleen cells was performed. The positive hybrids were cloned and ELISA was applied against different dilutions. The positive clones were transferred to a small tissue culture flask and after developing they were assayed against schizont extract and the different MSP-2 domains. The positive clones were expanded to large (75 cm(2)) flask and cultured under the same conditions, checking them using both ELISA and IFAT and the positive cells were frozen as soon as possible. RESULTS A total number of 7 fusions including 26 plates (2 496 wells) were performed, of which 1 336 hybrids were produced and the overall efficiency (1 336/2496 × 100) was about 53%. ELISA was performed to detect the positive hybrids against crude schizont extract by which the highest frequency to crude schizont extract was found for the supernatant of the hybrids produced in fusion number 3 (66 out of 315 hybrids). The supernatant of both B5 and F1 hybridoma cells were more positive against domain 2 of the MSP-2 recombinant protein in Western blotting test. Western blotting results also showed that different domains of the MSP-2 recombinant protein and also the MSP-2 of the P. falciparum parasite were recognized by some of the positive clones and also immune sera. CONCLUSIONS Bringing together all the results of this study it has been confirmed that some clones have recognized both schizont extract and different domains of the MSP-2 recombinant protein and therefore confirming the quality of the MSP-2 domains.
Collapse
Affiliation(s)
- Afra Khosravi
- Immunology Department, Faculty of Medicine, Ilam University of Medical Sciences, Ilam, Iran
| | | | | | | | | |
Collapse
|
43
|
Murungi LM, Kamuyu G, Lowe B, Bejon P, Theisen M, Kinyanjui SM, Marsh K, Osier FHA. A threshold concentration of anti-merozoite antibodies is required for protection from clinical episodes of malaria. Vaccine 2013; 31:3936-42. [PMID: 23800539 PMCID: PMC3763364 DOI: 10.1016/j.vaccine.2013.06.042] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 05/14/2013] [Accepted: 06/12/2013] [Indexed: 11/03/2022]
Abstract
Antibodies to selected Plasmodium falciparum merozoite antigens are often reported to be associated with protection from malaria in one epidemiological cohort, but not in another. Here, we sought to understand this paradox by exploring the hypothesis that a threshold concentration of antibodies is necessary for protection. We analyzed data from two independent cohorts along the Kenyan coast, one in which antibodies to AMA1, MSP-2 and MSP-3 were associated with protection from malaria (Chonyi) and another in which this association was not observed (Junju). We used a malaria reference reagent to standardize antibody measurements across both cohorts, and applied statistical methods to derive the threshold concentration of antibodies against each antigen that best correlated with a reduced risk of malaria (the protective threshold), in the Chonyi cohort. We then tested whether antibodies in Junju reached the protective threshold concentrations observed in the Chonyi cohort. Except for children under 3 years, the age-matched proportions of children achieving protective threshold concentrations of antibodies against AMA1 and MSP-2 were significantly lower in Junju compared to Chonyi (Fishers exact test, P<0.01). For MSP-3, this difference was significant only among 4-5 year olds. We conclude that although antibodies are commonly detected in malaria endemic populations, they may be present in concentrations that are insufficient for protection. Our results have implications for the analysis and interpretation of similar data from immuno-epidemiological studies.
Collapse
Affiliation(s)
- Linda M Murungi
- KEMRI Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya.
| | | | | | | | | | | | | | | |
Collapse
|
44
|
Ibara-Okabande R, Koukouikila-Koussounda F, Ndounga M, Vouvoungui J, Malonga V, Casimiro PN, Ibara JR, Sidibe A, Ntoumi F. Reduction of multiplicity of infections but no change in msp2 genetic diversity in Plasmodium falciparum isolates from Congolese children after introduction of artemisinin-combination therapy. Malar J 2012; 11:410. [PMID: 23217196 PMCID: PMC3543211 DOI: 10.1186/1475-2875-11-410] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 11/30/2012] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND In this first study conducted after the introduction of artemisinin-combination therapy (ACT), the major objective was to evaluate Plasmodium falciparum genetic diversity and multiplicity of infection in isolates from Congolese children between one and nine years of age enrolled and followed up for one year. The secondary objective was to characterize the msp2 profiles of P. falciparum isolates collected from successive malaria episodes in ten children who had four or more clinical episodes during the follow up. METHODS Three-hundred and thirteen children residing in southern part of Brazzaville participated in this study. Blood samples were obtained from all children at enrollment and checked for P. falciparum infection. Based on the one year follow-up data, two clinical groups were considered according to the number of malaria episodes presented over the follow up period: "protected"(children who did not experience any episode) and "unprotected" (those who experienced more that two episodes). Therefore, the msp2 genetic diversity of P. falciparum isolates collected at enrollment in the two groups was characterized by allele-specific nested PCR and compared. The msp2 profiles of P. falciparum isolates collected from successive malaria episodes was also characterized by allele-specific nested PCR. RESULTS Forty-three percent of FC27 and fifty-seven percent of 3D7 in protected vs fifty-six percent of FC27 and forty-four percent of 3D7 in isolates from unprotected children were detected. Seven and two alleles belonging to the FC27, and six and three alleles belonging to 3D7 families were distinguished in isolates from protected and unprotected children respectively. The mean multiplicity of infection (MOI) values at inclusion for the msp2 locus was 1.29 and 1.43 for protected and unprotected children respectively. 43 isolates were obtained from the ten children who had four or more clinical episodes during the follow up. A total of 63 alleles or fragments corresponding to 57% (36/63) FC27 and 43% (27/63) 3D7 were detected. The variant 400bp of FC27 was the most prevalent. 46% (20/43), 42% (18/43), 2% (1/43) and 2% (1/43) of isolates were found to have 1, 2, 3 and 4 parasite genotypes respectively and the mean MOI was 1.78. CONCLUSION This study shows that the introduction of ACT in the Republic of Congo has reduced the MOI but not the genetic diversity of P. falciparum isolates from children living in Southern districts of Brazzaville.
Collapse
Affiliation(s)
- Rod Ibara-Okabande
- Fondation Congolaise pour la Recherche Médicale, Brazzaville, Republic of Congo
| | | | | | | | | | | | | | | | | |
Collapse
|
45
|
Antigenic characterization of an intrinsically unstructured protein, Plasmodium falciparum merozoite surface protein 2. Infect Immun 2012; 80:4177-85. [PMID: 22966050 DOI: 10.1128/iai.00665-12] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Merozoite surface protein 2 (MSP2) is an abundant glycosylphosphatidylinositol (GPI)-anchored protein of Plasmodium falciparum, which is a potential component of a malaria vaccine. As all forms of MSP2 can be categorized into two allelic families, a vaccine containing two representative forms of MSP2 may overcome the problem of diversity in this highly polymorphic protein. Monomeric recombinant MSP2 is an intrinsically unstructured protein, but its conformational properties on the merozoite surface are unknown. This question is addressed here by analyzing the 3D7 and FC27 forms of recombinant and parasite MSP2 using a panel of monoclonal antibodies raised against recombinant MSP2. The epitopes of all antibodies, mapped using both a peptide array and by nuclear magnetic resonance (NMR) spectroscopy on full-length recombinant MSP2, were shown to be linear. The antibodies revealed antigenic differences, which indicate that the conserved N- and C-terminal regions, but not the central variable region, are less accessible in the parasite antigen. This appears to be an intrinsic property of parasite MSP2 and is not dependent on interactions with other merozoite surface proteins as the loss of some conserved-region epitopes seen using the immunofluorescence assay (IFA) on parasite smears was also seen on Western blot analyses of parasite lysates. Further studies of the structural basis of these antigenic differences are required in order to optimize recombinant MSP2 constructs being evaluated as potential vaccine components.
Collapse
|
46
|
A phase 1 trial of MSP2-C1, a blood-stage malaria vaccine containing 2 isoforms of MSP2 formulated with Montanide® ISA 720. PLoS One 2011; 6:e24413. [PMID: 21949716 PMCID: PMC3176224 DOI: 10.1371/journal.pone.0024413] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Accepted: 08/10/2011] [Indexed: 11/19/2022] Open
Abstract
Background In a previous Phase 1/2b malaria vaccine trial testing the 3D7 isoform of the malaria vaccine candidate Merozoite surface protein 2 (MSP2), parasite densities in children were reduced by 62%. However, breakthrough parasitemias were disproportionately of the alternate dimorphic form of MSP2, the FC27 genotype. We therefore undertook a dose-escalating, double-blinded, placebo-controlled Phase 1 trial in healthy, malaria-naïve adults of MSP2-C1, a vaccine containing recombinant forms of the two families of msp2 alleles, 3D7 and FC27 (EcMSP2-3D7 and EcMSP2-FC27), formulated in equal amounts with Montanide® ISA 720 as a water-in-oil emulsion. Methodology/Principal Findings The trial was designed to include three dose cohorts (10, 40, and 80 µg), each with twelve subjects receiving the vaccine and three control subjects receiving Montanide® ISA 720 adjuvant emulsion alone, in a schedule of three doses at 12-week intervals. Due to unexpected local reactogenicity and concern regarding vaccine stability, the trial was terminated after the second immunisation of the cohort receiving the 40 µg dose; no subjects received the 80 µg dose. Immunization induced significant IgG responses to both isoforms of MSP2 in the 10 µg and 40 µg dose cohorts, with antibody levels by ELISA higher in the 40 µg cohort. Vaccine-induced antibodies recognised native protein by Western blots of parasite protein extracts and by immunofluorescence microscopy. Although the induced anti-MSP2 antibodies did not directly inhibit parasite growth in vitro, IgG from the majority of individuals tested caused significant antibody-dependent cellular inhibition (ADCI) of parasite growth. Conclusions/Significance As the majority of subjects vaccinated with MSP2-C1 developed an antibody responses to both forms of MSP2, and that these antibodies mediated ADCI provide further support for MSP2 as a malaria vaccine candidate. However, in view of the reactogenicity of this formulation, further clinical development of MSP2-C1 will require formulation of MSP2 in an alternative adjuvant. Trial Registration Australian New Zealand Clinical Trials Registry 12607000552482
Collapse
|
47
|
Plasmodium falciparum serine repeat antigen 5 (SE36) as a malaria vaccine candidate. Vaccine 2011; 29:5837-45. [DOI: 10.1016/j.vaccine.2011.06.052] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 05/31/2011] [Accepted: 06/14/2011] [Indexed: 12/29/2022]
|
48
|
Khosravi A, Hommel M, Sayemiri K. Age-dependent antibody response to Plasmodium falciparum merozoite surface protein 2 (MSP-2). Parasite Immunol 2011; 33:145-57. [PMID: 21306398 DOI: 10.1111/j.1365-3024.2010.01260.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Merozoite surface protein 2 (MSP-2), a very immunogenic malaria antigen, is a highly polymorphic 45-53 kDa merozoite surface protein, which is regarded as a promising vaccine candidate. The highly polymorphic nature of MSP-2 suggests that the molecule can be involved in protective immunity against malaria. The antibody responses to MSP-2 antigen are mostly directed against polymorphic and dimorphic regions of the protein. The current study aimed at testing the reactivity of human sera from a malaria-endemic area of Gambia against MSP-2 regions 2, 3 and 4 compared to crude schizont extract in a period of 20 years. The age-dependent immunity was analysed in a manner of cross-sectional study (the data of the first visit) and also a longitudinal study design (analysing the data at four different time points from 1960 to 1980) testing the sera of 178 individuals randomly selected from the Keneba Serum Collection by using MSP-2 recombinant protein. The total IgG responses were measured by ELISA. Kolmogorov-Smirnov was used to check the normal distribution of OD, Hb and parasitaemia, and then Spearman correlation was applied to analyse the data. Most sera recognized, predominantly, the variable regions of the MSP-2, particularly the domain 3. The IgG response against all the antigens increased with age. The IgG responses against domain 3 of MSP-2 were associated with an increase in haemoglobin levels but a decrease in parasitaemia, suggesting that this immune response may be one of the most useful means for further studies on protective immunity against malaria.
Collapse
Affiliation(s)
- A Khosravi
- Immunology Department, Ilam University of Medical Sciences, Ilam, Iran.
| | | | | |
Collapse
|
49
|
Effect of HIV infection on the acute antibody response to malaria antigens in children: an observational study. Malar J 2011; 10:55. [PMID: 21375768 PMCID: PMC3066111 DOI: 10.1186/1475-2875-10-55] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2011] [Accepted: 03/05/2011] [Indexed: 11/30/2022] Open
Abstract
Background In sub-Saharan Africa, the distributions of malaria and HIV widely overlap. Among pregnant and non-pregnant adults, HIV affects susceptibility to malaria, its clinical course and impairs antibody responses to malaria antigens. However, the relationship between the two diseases in childhood, when most deaths from malaria occur, is less clear. It was previously reported that HIV is associated with admission to hospital in rural Kenya with severe malaria among children, except in infancy. HIV-infected children with severe malaria were older, had higher parasite density and increased mortality, raising a hypothesis that HIV interferes with naturally acquired immunity to malaria, hence with little effect at younger ages (a shorter history of exposure). To test this hypothesis, levels of anti-merozoite and schizont extract antibodies were compared between HIV-infected and uninfected children who participated in the original study. Methods IgG responses to malaria antigens that are potential targets for immunity to malaria (AMA1, MSP2, MSP3 and schizont extract) were compared between 115 HIV-infected and 115 age-matched, HIV-uninfected children who presented with severe malaria. The children were classified as high and low responders for each antigen and assigned antibody-response breadth scores according to the number of antigens to which they were responsive. A predictive logistic regression model was used to test if HIV was an effect modifier on the age-related acquisition of antibody responses, with age as a continuous variable. Results Point estimates of the responses to all antigens were lower amongst HIV-infected children, but this was only statistically significant for AMA1 (P = 0.028). HIV-infected children were less likely to be high responders to AMA1 [OR 0.44 (95%CI, 0.2-0.90) P = 0.024]. HIV was associated with a reduced breadth of responses to individual merozoite antigens (P = 0.02). HIV strongly modified the acquisition of antibodies against schizont extract with increasing age (P < 0.0001), but did not modify the rate of age-related acquisition of responses to individual merozoite antigens. Conclusions In children with severe malaria, HIV infection is associated with a lower magnitude and narrower breadth of IgG responses to merozoite antigens and stunting of age-related acquisition of the IgG antibody response to schizont extract.
Collapse
|
50
|
Strain-transcending Fc-dependent killing of Plasmodium falciparum by merozoite surface protein 2 allele-specific human antibodies. Infect Immun 2010; 79:1143-52. [PMID: 21189324 DOI: 10.1128/iai.01034-10] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
It is widely accepted that antibody responses against the human parasitic pathogen Plasmodium falciparum protect the host from the rigors of severe malaria and death. However, there is a continuing need for the development of in vitro correlate assays of immune protection. To this end, the capacity of human monoclonal and polyclonal antibodies in eliciting phagocytosis and parasite growth inhibition via Fcγ receptor-dependent mechanisms was explored. In examining the extent to which sequence diversity in merozoite surface protein 2 (MSP2) results in the evasion of antibody responses, an unexpectedly high level of heterologous function was measured for allele-specific human antibodies. The dependence on Fcγ receptors for opsonic phagocytosis and monocyte-mediated antibody-dependent parasite inhibition was demonstrated by the mutation of the Fc domain of monoclonal antibodies against both MSP2 and a novel vaccine candidate, peptide 27 from the gene PFF0165c. The described flow cytometry-based functional assays are expected to be useful for assessing immunity in naturally infected and vaccinated individuals and for prioritizing among blood-stage antigens for inclusion in blood-stage vaccines.
Collapse
|