1
|
Khattab A, Rezola M, Barroso M, Kyrklund M, Pihlajamaa T, Freitag TL, van Gemert GJ, Bousema T, Permi P, Turunen O, Sauerwein R, Luty AJF, Meri S. Hijacking the human complement inhibitor C4b-binding protein by the sporozoite stage of the Plasmodium falciparum parasite. Front Immunol 2022; 13:1051161. [PMID: 36479121 PMCID: PMC9720182 DOI: 10.3389/fimmu.2022.1051161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 11/02/2022] [Indexed: 11/22/2022] Open
Abstract
The complement system is considered the first line of defense against pathogens. Hijacking complement regulators from blood is a common evasion tactic of pathogens to inhibit complement activation on their surfaces. Here, we report hijacking of the complement C4b-binding protein (C4bp), the regulator of the classical and lectin pathways of complement activation, by the sporozoite (SPZ) stage of the Plasmodium falciparum parasite. This was shown by direct binding of radiolabeled purified C4bp to live SPZs as well as by binding of C4bp from human serum to SPZs in indirect immunofluorescence assays. Using a membrane-bound peptide array, peptides from the N-terminal domain (NTD) of P. falciparum circumsporozoite protein (CSP) were found to bind C4bp. Soluble biotinylated peptide covering the same region on the NTD and a recombinantly expressed NTD also bound C4bp in a dose-dependent manner. NTD-binding site on C4bp was mapped to the CCP1-2 of the C4bp α-chain, a common binding site for many pathogens. Native CSP was also co-immunoprecipitated with C4bp from human serum. Preventing C4bp binding to the SPZ surface negatively affected the SPZs gliding motility in the presence of functional complement and malaria hyperimmune IgG confirming the protective role of C4bp in controlling complement activation through the classical pathway on the SPZ surface. Incorporating the CSP-C4bp binding region into a CSP-based vaccine formulation could induce vaccine-mediated immunity that neutralizes this immune evasion region and increases the vaccine efficacy.
Collapse
Affiliation(s)
- Ayman Khattab
- Department of Bacteriology and Immunology, Haartman Institute, and Translational Immunology Research Program, University of Helsinki, Helsinki, Finland,Department of Nucleic Acid Research, Genetic Engineering and Biotechnology Research Institute, City of Scientific Research and Technological Applications, New Borg El-Arab, Alexandria, Egypt,*Correspondence: Ayman Khattab,
| | - Mikel Rezola
- Department of Bacteriology and Immunology, Haartman Institute, and Translational Immunology Research Program, University of Helsinki, Helsinki, Finland
| | - Marta Barroso
- Department of Bacteriology and Immunology, Haartman Institute, and Translational Immunology Research Program, University of Helsinki, Helsinki, Finland
| | - Mikael Kyrklund
- Department of Bacteriology and Immunology, Haartman Institute, and Translational Immunology Research Program, University of Helsinki, Helsinki, Finland,Department of Bioproducts and Biosystems, Aalto University, Espoo, Finland
| | - Tero Pihlajamaa
- Department of Clinical Chemistry, HUSLAB, Helsinki University Hospital, HUS Diagnostic Center, Helsinki, Finland
| | - Tobias L. Freitag
- Department of Bacteriology and Immunology, Haartman Institute, and Translational Immunology Research Program, University of Helsinki, Helsinki, Finland
| | | | - Teun Bousema
- Department of Medical Microbiology, Radboudumc, Nijmegen, Netherlands
| | - Perttu Permi
- Department of Chemistry, Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland,Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - Ossi Turunen
- Department of Bioproducts and Biosystems, Aalto University, Espoo, Finland,School of Forest Sciences, University of Eastern Finland, Joensuu, Finland
| | | | | | - Seppo Meri
- Department of Bacteriology and Immunology, Haartman Institute, and Translational Immunology Research Program, University of Helsinki, Helsinki, Finland,HUSLAB Diagnostic Center, Helsinki University Central Hospital, Helsinki, Finland,Department of Biomedical Sciences, Humanitas University, Milan, Italy
| |
Collapse
|
2
|
Andisi KC, Abdi AI. Analysis of var Gene Transcription Pattern Using DBLα Tags. Methods Mol Biol 2022; 2470:173-184. [PMID: 35881346 PMCID: PMC7613572 DOI: 10.1007/978-1-0716-2189-9_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
AbstractThe Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) antigens, which are encoded by a multigene family called var genes, are exported and inserted onto the surface of the infected erythrocytes. PfEMP1 plays a key role in the pathogenesis of severe malaria and are major targets of naturally acquired immunity. Studying the expression pattern of var genes in P. falciparum clinical isolates is crucial for understanding disease mechanism and immunity to malaria. However, var genes are highly variable, which makes it difficult to study their expression in clinical isolates obtained directly from malaria patients. In this chapter, we describe an approach for analysis of var gene expression that targets a region referred to as DBLα tag, which is relatively conserved in all var genes.
Collapse
|
3
|
Vanda K, Bobbili N, Matsunaga M, Chen JJ, Salanti A, Leke RFG, Taylor DW. The Development, Fine Specificity, and Importance of High-Avidity Antibodies to VAR2CSA in Pregnant Cameroonian Women Living in Yaoundé, an Urban City. Front Immunol 2021; 12:610108. [PMID: 33717094 PMCID: PMC7953046 DOI: 10.3389/fimmu.2021.610108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 01/07/2021] [Indexed: 11/25/2022] Open
Abstract
Pregnant women infected with Plasmodium falciparum often produce antibodies (Abs) to VAR2CSA, a ligand that binds to placental chondroitin sulfate A causing placental malaria (PM). Antibodies to VAR2CSA are associated with improved pregnancy outcomes. Antibody avidity is a surrogate marker for the extent of maturation of the humoral immune response. Little is known about high avidity Abs to VAR2CSA for women living in urban African cities. Therefore, this study sought to determine: i) if high avidity Abs to full-length VAR2CSA (FV2) increase with gravidity in women in Yaoundé, Cameroon exposed to ~ 0.3-1.1 infectious mosquito bites per month, ii) if high avidity Abs to FV2 are directed against a specific region of VAR2CSA, and iii) if having high avidity Abs to FV2 improve pregnancy outcomes. Plasma samples collected at delivery from 695 women who had Abs to FV2 were evaluated. Ab levels and the Avidity Index (AI), defined as the percent Abs remaining bound to FV2 after incubation with 3M NH4SCN, were determined. Similar Ab levels to FV2 were present in women of all gravidities (G1 through 6+; p=0.80), except significantly lower levels were detected in PM−negative (PM−) primigravidae (p <0.001). Median Ab avidities increased between gravidity 1 and 2 (p<0.001) and remained stable thereafter (G3-G6+: p=0.51). These results suggest that B cell clonal expansion began during the first pregnancy, with clonal selection primarily occurring during the second. However, the majority of women (84%) had AI <35, a level of high avidity Abs previously reported to be associated with improved pregnancy outcomes. When plasma from 107 Cameroonian women was tested against 8 different regions of FV2, high avidity Abs were predominately restricted to DBL5 with median AI of 50 compared to AI <25 for the other domains. The only significance influence of high avidity Abs on pregnancy outcome was that babies born to mothers with AI above the median were 104 g heavier than babies born to women with AI below the median (p=0.045). These results suggest that a vaccine that boosts maturation of the immune response to VAR2CSA may be beneficial for women residing in urban areas.
Collapse
Affiliation(s)
- Koko Vanda
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, United States
| | - Naveen Bobbili
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, United States
| | - Masako Matsunaga
- Department of Quantitative Health Sciences, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, United States
| | - John J Chen
- Department of Quantitative Health Sciences, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, United States
| | - Ali Salanti
- Centre for Medical Parasitology, Department for Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and Department of Infectious Disease, Copenhagen University Hospital, Copenhagen, Denmark
| | - Rose F G Leke
- Faculty of Medicine and Biomedical Research, The Biotechnology Center, University of Yaoundé 1, Yaoundé, Cameroon
| | - Diane Wallace Taylor
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, United States
| |
Collapse
|
4
|
Gnidehou S, Yanow SK. VAR2CSA Antibodies in Non-Pregnant Populations. Trends Parasitol 2020; 37:65-76. [PMID: 33067131 DOI: 10.1016/j.pt.2020.09.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/16/2020] [Accepted: 09/18/2020] [Indexed: 11/18/2022]
Abstract
The Plasmodium falciparum protein VAR2CSA is a critical mediator of placental malaria, and VAR2CSA antibodies (IgGs) are important to protect pregnant women. Although infrequently detected outside pregnancy, VAR2CSA IgGs were reported in men and children from Colombia and Brazil and in select African populations. These findings raise questions about the specificity of VAR2CSA IgGs and the mechanisms by which they are acquired outside pregnancy. Here we review the data on VAR2CSA IgGs in men and children from different malaria-endemic regions. We discuss experimental factors that may affect interpretation of the serological data and consider the biological relevance of VAR2CSA IgGs in non-pregnant populations. We propose potential mechanisms for the acquisition of VARCSA IgGs outside of pregnancy. We identify knowledge gaps and research priorities.
Collapse
Affiliation(s)
- Sedami Gnidehou
- Campus Saint-Jean, University of Alberta, Edmonton, AB, Canada; Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada.
| | - Stephanie K Yanow
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada; School of Public Health, University of Alberta, Edmonton, AB, Canada
| |
Collapse
|
5
|
Doesn’t It All Come Down to Function? How To Correlate VAR2CSA Antibodies with Protection. mSphere 2020; 5:5/3/e00521-20. [PMID: 32581073 PMCID: PMC7316495 DOI: 10.1128/msphere.00521-20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
6
|
Cutts JC, Agius PA, Zaw Lin, Powell R, Moore K, Draper B, Simpson JA, Fowkes FJI. Pregnancy-specific malarial immunity and risk of malaria in pregnancy and adverse birth outcomes: a systematic review. BMC Med 2020; 18:14. [PMID: 31941488 PMCID: PMC6964062 DOI: 10.1186/s12916-019-1467-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 11/11/2019] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND In endemic areas, pregnant women are highly susceptible to Plasmodium falciparum malaria characterized by the accumulation of parasitized red blood cells (pRBC) in the placenta. In subsequent pregnancies, women develop protective immunity to pregnancy-associated malaria and this has been hypothesized to be due to the acquisition of antibodies to the parasite variant surface antigen VAR2CSA. In this systematic review we provide the first synthesis of the association between antibodies to pregnancy-specific P. falciparum antigens and pregnancy and birth outcomes. METHODS We conducted a systematic review and meta-analysis of population-based studies (published up to 07 June 2019) of pregnant women living in P. falciparum endemic areas that examined antibody responses to pregnancy-specific P. falciparum antigens and outcomes including placental malaria, low birthweight, preterm birth, peripheral parasitaemia, maternal anaemia, and severe malaria. RESULTS We searched 6 databases and identified 33 studies (30 from Africa) that met predetermined inclusion and quality criteria: 16 studies contributed estimates in a format enabling inclusion in meta-analysis and 17 were included in narrative form only. Estimates were mostly from cross-sectional data (10 studies) and were heterogeneous in terms of magnitude and direction of effect. Included studies varied in terms of antigens tested, methodology used to measure antibody responses, and epidemiological setting. Antibody responses to pregnancy-specific pRBC and VAR2CSA antigens, measured at delivery, were associated with placental malaria (9 studies) and may therefore represent markers of infection, rather than correlates of protection. Antibody responses to pregnancy-specific pRBC, but not recombinant VAR2CSA antigens, were associated with trends towards protection from low birthweight (5 studies). CONCLUSIONS Whilst antibody responses to several antigens were positively associated with the presence of placental and peripheral infections, this review did not identify evidence that any specific antibody response is associated with protection from pregnancy-associated malaria across multiple populations. Further prospective cohort studies using standardized laboratory methods to examine responses to a broad range of antigens in different epidemiological settings and throughout the gestational period, will be necessary to identify and prioritize pregnancy-specific P. falciparum antigens to advance the development of vaccines and serosurveillance tools targeting pregnant women.
Collapse
Affiliation(s)
- Julia C Cutts
- Burnet Institute, 85 Commercial Road, Melbourne, Victoria, 3004, Australia.
| | - Paul A Agius
- Burnet Institute, 85 Commercial Road, Melbourne, Victoria, 3004, Australia.,Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia
| | - Zaw Lin
- Burnet Institute, 85 Commercial Road, Melbourne, Victoria, 3004, Australia.,Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia
| | - Rosanna Powell
- Burnet Institute, 85 Commercial Road, Melbourne, Victoria, 3004, Australia
| | - Kerryn Moore
- Burnet Institute, 85 Commercial Road, Melbourne, Victoria, 3004, Australia.,Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia
| | - Bridget Draper
- Burnet Institute, 85 Commercial Road, Melbourne, Victoria, 3004, Australia
| | - Julie A Simpson
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia
| | - Freya J I Fowkes
- Burnet Institute, 85 Commercial Road, Melbourne, Victoria, 3004, Australia. .,Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia. .,Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia. .,Department of Infectious Diseases, Monash University, Melbourne, Australia.
| |
Collapse
|
7
|
Ataíde R, Mayor A, Rogerson SJ. Malaria, primigravidae, and antibodies: knowledge gained and future perspectives. Trends Parasitol 2013; 30:85-94. [PMID: 24388420 DOI: 10.1016/j.pt.2013.12.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 12/08/2013] [Accepted: 12/08/2013] [Indexed: 10/25/2022]
Abstract
Pregnant women have an increased risk of malaria infection, independent of previously acquired immunity. Women in their first pregnancy and children under the age of five are the primary victims of malaria worldwide. Pregnant women develop antibodies against placenta-adhesive parasites in a parity-dependent manner. Various efforts to understand the targets, quality, and quantity of this antibody response could aid the design of an effective vaccine against placental malaria. This review focuses on the research that has led to the current understanding of the antibody response that primigravidae (PG) acquire to Plasmodium falciparum malaria and draws from this knowledge to suggest serology and PG as sentinels for malaria transmission.
Collapse
Affiliation(s)
- Ricardo Ataíde
- Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Melbourne, Australia.
| | - Alfredo Mayor
- Barcelona Centre for International Health Research (CRESIB), Hospital Clínic-Universitat de Barcelona, Barcelona, Spain; Centro de Investigação em Saúde da Manhiça (CISM), Manhiça, Mozambique
| | - Stephen J Rogerson
- Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Melbourne, Australia
| |
Collapse
|
8
|
Nasr A, Hamid O, Al-Ghamdi A, Allam G. Anti-malarial IgG subclasses pattern and FcγRIIa (CD32) polymorphism among pregnancy-associated malaria in semi-immune Saudi women. Malar J 2013; 12:110. [PMID: 23517907 PMCID: PMC3608938 DOI: 10.1186/1475-2875-12-110] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 03/16/2013] [Indexed: 01/06/2023] Open
Abstract
Background Pregnant women remain are at an increased risk of malaria with primigravidae being at the highest risk. Genetic polymorphism of the Fc receptor IIa for immunologlobulin (Ig) G (FcγRIIa) determines IgG subclass binding. Protection against pregnancy-associated malaria (PAM) is associated with the production of IgG specific for apical membrane antigen-1 (AMA-1). The present study was undertaken to examine the relationship between specific IgG/IgG subclasses and malaria infection. The second aim of the study is to examine the association between FcγRIIa R/H131 polymorphism in correlation with specific anti-malarial IgG antibodies of AMA-1 distribution and asymptomatic malaria infection among Saudi women living in the southern part of Saudi Arabia. Methods One hundred and twenty pregnant women living in an area of meso-endemic Plasmodium falciparum malaria infection were consecutively enrolled onto the study. These pregnant women were asymptomatic and attending routine antenatal clinics. The levels of plasma antibodies (IgG and subclasses AMA-1) were measured using indirect enzyme-linked immunosorbent assays (ELISA). Genotyping of FcγRIIa-R/H131 dimorphism was performed using gene-specific polymerase chain reaction (PCR) amplification with allele-specific restriction enzyme digestion (BstU1) of the PCR product. Results A total of sixty-two (52%) pregnant women was diagnosed with asymptomatic malarial infection (ASM) compared with 58 (48%) malaria free controls (MFC). In the ASM group, there were high levels of anti-malarial IgG1 and IgG3, when compared to MFC (P value <0.001, respectively). The FcγRIIa-R/R131 genotype and R131 were found to be statistically significantly more prevalent in the ASM group when compared to the MFC group [55% for ASM versus 12% for MFC, odds ratio (OR) 5.62, 95% confidence interval (CI)= (2.03- 15.58), P value= 0.001]. However, the H/H131 genotype showed statistically significant association with MFC [14% for ASM versus 50% for MFC, OR(0.36), 95% CI= (0.14- 0.95), P value= 0.03]. Conclusions The study revealed that the ASM patients had higher anti-malarial IgG and IgG subclasses antibody levels when compared to the MFC. The FcγRIIa-R/R131 genotype and R131 allele were found to be statistically prevalent in the ASM when compared to the MFC group. The individuals carrying H/H131 were consistently associated with higher levels of anti-malarial IgG subclasses.
Collapse
Affiliation(s)
- Amre Nasr
- Department of Microbiology, College of Medicine, Taif University, PO Box 888, Taif, Saudi Arabia.
| | | | | | | |
Collapse
|
9
|
Khattab A, Kremsner P, Meri S. Complement activation in primiparous women from a malaria endemic area is associated with reduced birthweight. Placenta 2013; 34:162-7. [DOI: 10.1016/j.placenta.2012.11.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 11/22/2012] [Accepted: 11/22/2012] [Indexed: 10/27/2022]
|
10
|
Tutterrow YL, Salanti A, Avril M, Smith JD, Pagano IS, Ako S, Fogako J, Leke RGF, Taylor DW. High avidity antibodies to full-length VAR2CSA correlate with absence of placental malaria. PLoS One 2012; 7:e40049. [PMID: 22761948 PMCID: PMC3383675 DOI: 10.1371/journal.pone.0040049] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Accepted: 05/31/2012] [Indexed: 11/29/2022] Open
Abstract
VAR2CSA mediates sequestration of Plasmodium falciparum-infected erythrocytes in the placenta, increasing the risk of poor pregnancy outcomes. Naturally acquired antibodies (Ab) to placental parasites at delivery have been associated with improved pregnancy outcomes, but Ab levels and how early in pregnancy Ab must be present in order to eliminate placental parasites before delivery remains unknown. Antibodies to individual Duffy-binding like domains of VAR2CSA have been studied, but the domains lack many of the conformational epitopes present in full-length VAR2CSA (FV2). Thus, the purpose of this study was to describe the acquisition of Ab to FV2 in women residing in high and low transmission areas and determine how Ab levels during pregnancy correlate with clearance of placental parasites. Plasma samples collected monthly throughout pregnancy from pregnant women living in high and low transmission areas in Cameroon were evaluated for Ab to FV2 and the proportion of high avidity Ab (i.e., Ab that remain bound in the presence of 3M NH4SCN) was assessed. Ab levels and proportion of high avidity Ab were compared between women with placental malaria (PM+) and those without (PM−) at delivery. Results showed that PM− women had significantly higher Ab levels (p = 0.0047) and proportion of high avidity Ab (p = 0.0009) than PM+ women throughout pregnancy. Specifically, women with moderate to high Ab levels (>5,000 MFI) and those with ≥35% high avidity Ab at 5–6 months were found to have 2.3 (95% CI, 1.0–4.9) and 7.6-fold (p = 0.0013, 95% CI: 1.2–50.0) reduced risk of placental malaria, respectively. These data show that high levels of Ab to FV2, particularly those with high avidity for FV2, produced by mid-pregnancy are important in clearing parasites from the placenta. Both high Ab levels and proportion of high avidity Ab to FV2 may serve as correlates of protection for assessing immunity against placental malaria.
Collapse
Affiliation(s)
- Yeung Lo Tutterrow
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawai'i-Mānoa, Honolulu, Hawaii, United States of America
| | - Ali Salanti
- Department of International Health, Immunology and Microbiology, Centre for Medical Parasitology, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Marion Avril
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Joseph D. Smith
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Ian S. Pagano
- Cancer Research Center, University of Hawaii-Mānoa, Honolulu, Hawaii, United States of America
| | - Simon Ako
- The Biotechnology Center, University of Yaoundé I, Yaoundé, Cameroon
| | - Josephine Fogako
- The Biotechnology Center, University of Yaoundé I, Yaoundé, Cameroon
| | - Rose G. F. Leke
- The Biotechnology Center, University of Yaoundé I, Yaoundé, Cameroon
| | - Diane Wallace Taylor
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawai'i-Mānoa, Honolulu, Hawaii, United States of America
- * E-mail:
| |
Collapse
|
11
|
High levels of antibodies to multiple domains and strains of VAR2CSA correlate with the absence of placental malaria in Cameroonian women living in an area of high Plasmodium falciparum transmission. Infect Immun 2012; 80:1479-90. [PMID: 22331427 DOI: 10.1128/iai.00071-12] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Placental malaria, caused by sequestration of Plasmodium falciparum-infected erythrocytes in the placenta, is associated with increased risk of maternal morbidity and poor birth outcomes. The parasite antigen VAR2CSA (variant surface antigen 2-chondroitin sulfate A) is expressed on infected erythrocytes and mediates binding to chondroitin sulfate A, initiating inflammation and disrupting homeostasis at the maternal-fetal interface. Although antibodies can prevent sequestration, it is unclear whether parasite clearance is due to antibodies to a single Duffy binding-like (DBL) domain or to an extensive repertoire of antibodies to multiple DBL domains and allelic variants. Accordingly, plasma samples collected longitudinally from pregnant women were screened for naturally acquired antibodies against an extensive panel of VAR2CSA proteins, including 2 to 3 allelic variants for each of 5 different DBL domains. Analyses were performed on plasma samples collected from 3 to 9 months of pregnancy from women living in areas in Cameroon with high and low malaria transmission. The results demonstrate that high antibody levels to multiple VAR2CSA domains, rather than a single domain, were associated with the absence of placental malaria when antibodies were present from early in the second trimester until term. Absence of placental malaria was associated with increasing antibody breadth to different DBL domains and allelic variants in multigravid women. Furthermore, the antibody responses of women in the lower-transmission site had both lower magnitude and lesser breadth than those in the high-transmission site. These data suggest that immunity to placental malaria results from high antibody levels to multiple VAR2CSA domains and allelic variants and that antibody breadth is influenced by malaria transmission intensity.
Collapse
|
12
|
Expression of Plasmodium falciparum 3D7 STEVOR proteins for evaluation of antibody responses following malaria infections in naïve infants. Parasitology 2007; 135:155-67. [PMID: 17931459 DOI: 10.1017/s0031182007003794] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Clinical immunity to Plasmodium falciparum malaria develops after repeated exposure to the parasite. At least 2 P. falciparum variant antigens encoded by multicopy gene families (var and rif) are targets of this adaptive antibody-mediated immunity. A third multigene family of variant antigens comprises the stevor genes. Here, 4 different stevor sequences were selected for cloning and expression in Escherichia coli and His6-tagged fusion proteins were used for assessing the development of immunity. In a cross-sectional analysis of clinically immune adults living in a malaria endemic area in Ghana, high levels of anti-STEVOR IgG antibody titres were determined in ELISA. A cross-sectional study of 90 nine-month-old Ghanaian infants using 1 recombinant STEVOR showed that the antibody responses correlated positively with the number of parasitaemia episodes. In a longitudinal investigation of 17 immunologically naïve 9-month-old infants, 3 different patterns of anti-STEVOR antibody responses could be distinguished (high, transient and low). Children with high anti-STEVOR-antibody levels exhibited an elevated risk for developing parasitaemia episodes. Overall, a protective effect could not be attributed to antibodies against the STEVOR proteins chosen for the study presented here.
Collapse
|
13
|
Keen J, Serghides L, Ayi K, Patel SN, Ayisi J, van Eijk A, Steketee R, Udhayakumar V, Kain KC. HIV impairs opsonic phagocytic clearance of pregnancy-associated malaria parasites. PLoS Med 2007; 4:e181. [PMID: 17535103 PMCID: PMC1880852 DOI: 10.1371/journal.pmed.0040181] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2006] [Accepted: 03/30/2007] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Primigravid (PG) women are at risk for pregnancy-associated malaria (PAM). Multigravid (MG) women acquire protection against PAM; however, HIV infection impairs this protective response. Protection against PAM is associated with the production of IgG specific for variant surface antigens (VSA-PAM) expressed by chondroitin sulfate A (CSA)-adhering parasitized erythrocytes (PEs). We hypothesized that VSA-PAM-specific IgG confers protection by promoting opsonic phagocytosis of PAM isolates and that HIV infection impairs this response. METHODS AND FINDINGS We assessed the ability of VSA-PAM-specific IgG to promote opsonic phagocytosis of CSA-adhering PEs and the impact of HIV infection on this process. Opsonic phagocytosis assays were performed using the CSA-adherent parasite line CS2 and human and murine macrophages. CS2 PEs were opsonized with plasma or purified IgG subclasses from HIV-negative or HIV-infected PG and MG Kenyan women or sympatric men. Levels of IgG subclasses specific for VSA-PAM were compared in HIV-negative and HIV-infected women by flow cytometry. Plasma from HIV-negative MG women, but not PG women or men, promoted the opsonic phagocytosis of CSA-binding PEs (p < 0.001). This function depended on VSA-PAM-specific plasma IgG1 and IgG3. HIV-infected MG women had significantly lower plasma opsonizing activity (median phagocytic index 46 [interquartile range (IQR) 18-195] versus 251 [IQR 93-397], p = 0.006) and levels of VSA-PAM-specific IgG1 (mean fluorescence intensity [MFI] 13 [IQR 11-20] versus 30 [IQR 23-41], p < 0.001) and IgG3 (MFI 17 [IQR 14-23] versus 28 [IQR 23-37], p < 0.001) than their HIV-negative MG counterparts. CONCLUSIONS Opsonic phagocytosis may represent a novel correlate of protection against PAM. HIV infection may increase the susceptibility of multigravid women to PAM by impairing this clearance mechanism.
Collapse
Affiliation(s)
- Jessica Keen
- Faculty of Medicine, University of Toronto, Toronto, Canada
| | - Lena Serghides
- Faculty of Medicine, University of Toronto, Toronto, Canada
- McLaughlin-Rotman Centre, McLaughlin Center for Molecular Medicine, University of Toronto, Toronto, Canada
- University Health Network, Toronto, Canada
| | - Kodjo Ayi
- Faculty of Medicine, University of Toronto, Toronto, Canada
| | - Samir N Patel
- Faculty of Medicine, University of Toronto, Toronto, Canada
| | - John Ayisi
- Center for Vector Biology and Control Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Anne van Eijk
- Center for Vector Biology and Control Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Richard Steketee
- Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Venkatachalam Udhayakumar
- Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Kevin C Kain
- Faculty of Medicine, University of Toronto, Toronto, Canada
- McLaughlin-Rotman Centre, McLaughlin Center for Molecular Medicine, University of Toronto, Toronto, Canada
- University Health Network, Toronto, Canada
- * To whom correspondence should be addressed. E-mail:
| |
Collapse
|
14
|
Beeson JG, Duffy PE. The immunology and pathogenesis of malaria during pregnancy. Curr Top Microbiol Immunol 2006; 297:187-227. [PMID: 16265906 DOI: 10.1007/3-540-29967-x_6] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Women in endemic areas become highly susceptible to malaria during first and second pregnancies, despite immunity acquired after years of exposure. Recent insights have advanced our understanding of pregnancy malaria caused by Plasmodium falciparum, which is responsible for the bulk of severe disease and death. Accumulation of parasitized erythrocytes in the blood spaces of the placenta is a key feature of maternal infection with P. falciparum. Placental parasites express surface ligands and antigens that differ from those of other P. falciparum variants, facilitating evasion of existing immunity, and mediate adhesion to specific molecules, such as chondroitin sulfate A, in the placenta. The polymorphic and clonally variant P. falciparum erythrocyte membrane protein 1, encoded by var genes, binds to placental receptors in vitro and may be the target of protective antibodies. An intense infiltration of immune cells, including macrophages, into the placental intervillous spaces, and the production of pro-inflammatory cytokines often occur in response to infection, and are associated with low birth weight and maternal anemia. Expression of alpha and beta chemokines may initiate or facilitate this cellular infiltration during placental malaria. Specific immunity against placental-binding parasites may prevent infection or facilitate clearance of parasites prior to the influx of inflammatory cells, thereby avoiding a cascade of events leading to disease and death. Much less is known about pathogenic processes in P. vivax infections, and corresponding immune responses. Emerging knowledge of the pathogenesis and immunology of malaria in pregnancy will increasingly lead to new opportunities for the development of therapeutic and preventive interventions and new tools for diagnosis and monitoring.
Collapse
Affiliation(s)
- J G Beeson
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.
| | | |
Collapse
|
15
|
Abstract
That humans in endemic areas become immune to malaria offers encouragement to the idea of developing protective vaccines. However natural immunity is relatively inefficient, being bought at the cost of substantial childhood mortality, and current vaccines are only partially protective. Understanding potential targets and mechanisms of protective immunity is important in the development and evaluation of future vaccines. Some of the problems in identifying such targets and mechanisms in humans naturally exposed to malaria may stem from conceptual and methodological issues related to defining who in a population is susceptible, problems in defining immune responsiveness at single time points and issues related to antigenic polymorphism, as well as the failure of many current approaches to examine functional aspects of the immune response. Protective immune responses may be directed to the pre erythrocytic parasite, to the free merozoite of the blood stage parasite or to new antigens induced on the infected red cell surface. Tackling the methodological issues of defining protection and immune response, together with studies that combine functional assays with new approaches such as allelic exchange and gene knock out offer opportunities for better defining key targets and mechanisms.
Collapse
Affiliation(s)
- K Marsh
- KEMRI Centre for Geographic Medicine Research Coast (CGMRC), PO Box 230, Kilifi, Kenya.
| | | |
Collapse
|
16
|
Hviid L. The immuno-epidemiology of pregnancy-associated Plasmodium falciparum malaria: a variant surface antigen-specific perspective. Parasite Immunol 2004; 26:477-86. [PMID: 15771683 DOI: 10.1111/j.0141-9838.2004.00733.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Women living in areas of intense P. falciparum transmission have acquired substantial protective immunity to malaria when they reach childbearing age. Nevertheless, pregnancies in such areas are associated with substantial malaria-related morbidity and mortality, particularly among women of low parity. The parity-dependency of susceptibility to malaria in pregnant women suggests that protective immunity to this type of malaria can be developed. However, until recently it has been poorly understood why the clinical protection against malaria, which young women in endemic areas acquire well before their first pregnancy, is suddenly rendered inadequate when they become pregnant, only to be regained during the course of a few pregnancies. In this article, I discuss some recent immuno-epidemiological studies of pregnancy-associated malaria, which, in combination with the generally improved understanding of how protective immunity to P. falciparum malaria operates and is acquired, have provided important insights into this enigma.
Collapse
Affiliation(s)
- L Hviid
- Centre for Medical Parasitology at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet) and Institute for Medical Microbiology and Immunology, University of Copenhagen, Copenhagen Ø, Denmark.
| |
Collapse
|
17
|
Sharling L, Enevold A, Sowa KMP, Staalsoe T, Arnot DE. Antibodies from malaria-exposed pregnant women recognize trypsin resistant epitopes on the surface of Plasmodium falciparum-infected erythrocytes selected for adhesion to chondroitin sulphate A. Malar J 2004; 3:31. [PMID: 15350207 PMCID: PMC517943 DOI: 10.1186/1475-2875-3-31] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2004] [Accepted: 09/06/2004] [Indexed: 11/17/2022] Open
Abstract
Background The ability of Plasmodium falciparum-infected erythrocytes to adhere to the microvasculature endothelium is thought to play a causal role in malaria pathogenesis. Cytoadhesion to endothelial receptors is generally found to be highly sensitive to trypsinization of the infected erythrocyte surface. However, several studies have found that parasite adhesion to placental receptors can be markedly less sensitive to trypsin. This study investigates whether chondroitin sulphate A (CSA) binding parasites express trypsin-resistant variant surface antigens (VSA) that bind female-specific antibodies induced as a result of pregnancy associated malaria (PAM). Methods Fluorescence activated cell sorting (FACS) was used to measure the levels of adult Scottish and Ghanaian male, and Ghanaian pregnant female plasma immunoglobulin G (IgG) that bind to the surface of infected erythrocytes. P. falciparum clone FCR3 cultures were used to assay surface IgG binding before and after selection of the parasite for adhesion to CSA. The effect of proteolytic digestion of parasite erythrocyte surface antigens on surface IgG binding and adhesion to CSA and hyaluronic acid (HA) was also studied. Results P. falciparum infected erythrocytes selected for adhesion to CSA were found to express trypsin-resistant VSA that are the target of naturally acquired antibodies from pregnant women living in a malaria endemic region of Ghana. However in vitro adhesion to CSA and HA was relatively trypsin sensitive. An improved labelling technique for the detection of VSA expressed by CSA binding isolates has also been described. Conclusion The VSA expressed by CSA binding P. falciparum isolates are currently considered potential targets for a vaccine against PAM. This study identifies discordance between the trypsin sensitivity of CSA binding and surface recognition of CSA selected parasites by serum IgG from malaria exposed pregnant women. Thus, the complete molecular definition of an antigenic P. falciparum erythrocyte surface protein that can be used as a malaria in pregnancy vaccine has not yet been achieved.
Collapse
MESH Headings
- Animals
- Antibodies, Protozoan/blood
- Antibodies, Protozoan/immunology
- Antigens, Protozoan/blood
- Antigens, Protozoan/drug effects
- Antigens, Protozoan/immunology
- Antigens, Surface/blood
- Antigens, Surface/drug effects
- Antigens, Surface/immunology
- Cattle
- Cell Adhesion
- Chondroitin Sulfates/metabolism
- Epitopes/blood
- Epitopes/drug effects
- Epitopes/immunology
- Erythrocytes/immunology
- Erythrocytes/parasitology
- Female
- Flow Cytometry
- Humans
- Hyaluronic Acid/metabolism
- Immunoglobulin G/blood
- Immunoglobulin G/immunology
- Malaria, Falciparum/blood
- Malaria, Falciparum/immunology
- Male
- Plasmodium falciparum/immunology
- Plasmodium falciparum/physiology
- Pregnancy
- Pregnancy Complications, Parasitic/blood
- Pregnancy Complications, Parasitic/immunology
- Protozoan Proteins/blood
- Protozoan Proteins/drug effects
- Protozoan Proteins/immunology
- Trypsin/pharmacology
Collapse
Affiliation(s)
- Lisa Sharling
- Institute of Cell, Animal and Population Biology, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh, EH9 3JT, Scotland, UK
| | - Anders Enevold
- Centre for Medical Parasitology, Department of Infectious Diseases M7641. Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen Ø, Denmark
| | - Kordai MP Sowa
- Institute of Cell, Animal and Population Biology, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh, EH9 3JT, Scotland, UK
| | - Trine Staalsoe
- Centre for Medical Parasitology, Department of Infectious Diseases M7641. Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen Ø, Denmark
| | - David E Arnot
- Institute of Cell, Animal and Population Biology, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh, EH9 3JT, Scotland, UK
| |
Collapse
|