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Rosenkranz M, Nkumama IN, Ogwang R, Kraker S, Blickling M, Mwai K, Odera D, Tuju J, Fürle K, Frank R, Chepsat E, Kapulu MC, Study Team CS, Osier FH. Full-length MSP1 is a major target of protective immunity after controlled human malaria infection. Life Sci Alliance 2024; 7:e202301910. [PMID: 38803222 PMCID: PMC11106525 DOI: 10.26508/lsa.202301910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 05/08/2024] [Accepted: 05/08/2024] [Indexed: 05/29/2024] Open
Abstract
The merozoite surface protein 1 (MSP1) is the most abundant protein on the surface of the invasive merozoite stages of Plasmodium falciparum and has long been considered a key target of protective immunity. We used samples from a single controlled human malaria challenge study to test whether the full-length version of MSP1 (MSP1FL) induced antibodies that mediated Fc-IgG functional activity in five independent assays. We found that anti-MSP1FL antibodies induced complement fixation via C1q, monocyte-mediated phagocytosis, neutrophil respiratory burst, and natural killer cell degranulation as well as IFNγ production. Activity in each of these assays was strongly associated with protection. The breadth of MSP1-specific Fc-mediated effector functions was more strongly associated with protection than the individual measures and closely mirrored what we have previously reported using the same assays against merozoites. Our findings suggest that MSP1FL is an important target of functional antibodies that contribute to a protective immune response against malaria.
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Affiliation(s)
- Micha Rosenkranz
- https://ror.org/013czdx64 Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Irene N Nkumama
- B Cell Immunology, German Cancer Research Centre, Heidelberg, Germany
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Rodney Ogwang
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Sara Kraker
- https://ror.org/013czdx64 Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Marie Blickling
- https://ror.org/013czdx64 Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Kennedy Mwai
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- Epidemiology and Biostatistics Division, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
| | - Dennis Odera
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - James Tuju
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Biotechnology and Biochemistry, Pwani University, Kilifi, Kenya
| | - Kristin Fürle
- https://ror.org/013czdx64 Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Roland Frank
- https://ror.org/013czdx64 Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Emily Chepsat
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Melissa C Kapulu
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Chmi-Sika Study Team
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Faith Ha Osier
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- https://ror.org/041kmwe10 Department of Life Sciences, Imperial College London, London, UK
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Nkumama IN, Ogwang R, Odera D, Musasia F, Mwai K, Nyamako L, Murungi L, Tuju J, Fürle K, Rosenkranz M, Kimathi R, Njuguna P, Hamaluba M, Kapulu MC, Frank R, Osier FHA. Breadth of Fc-mediated effector function correlates with clinical immunity following human malaria challenge. Immunity 2024; 57:1215-1224.e6. [PMID: 38788711 DOI: 10.1016/j.immuni.2024.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 03/19/2024] [Accepted: 05/01/2024] [Indexed: 05/26/2024]
Abstract
Malaria is a life-threatening disease of global health importance, particularly in sub-Saharan Africa. The growth inhibition assay (GIA) is routinely used to evaluate, prioritize, and quantify the efficacy of malaria blood-stage vaccine candidates but does not reliably predict either naturally acquired or vaccine-induced protection. Controlled human malaria challenge studies in semi-immune volunteers provide an unparalleled opportunity to robustly identify mechanistic correlates of protection. We leveraged this platform to undertake a head-to-head comparison of seven functional antibody assays that are relevant to immunity against the erythrocytic merozoite stage of Plasmodium falciparum. Fc-mediated effector functions were strongly associated with protection from clinical symptoms of malaria and exponential parasite multiplication, while the gold standard GIA was not. The breadth of Fc-mediated effector function discriminated clinical immunity following the challenge. These findings present a shift in the understanding of the mechanisms that underpin immunity to malaria and have important implications for vaccine development.
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Affiliation(s)
- Irene N Nkumama
- Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany; Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute, Wellcome Trust Research Programme, Kilifi, Kenya; European Vaccine Initiative, Heidelberg, Germany
| | - Rodney Ogwang
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute, Wellcome Trust Research Programme, Kilifi, Kenya
| | - Dennis Odera
- Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany; Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute, Wellcome Trust Research Programme, Kilifi, Kenya
| | - Fauzia Musasia
- Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Kennedy Mwai
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute, Wellcome Trust Research Programme, Kilifi, Kenya; Epidemiology and Biostatistics Division, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
| | - Lydia Nyamako
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute, Wellcome Trust Research Programme, Kilifi, Kenya
| | - Linda Murungi
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute, Wellcome Trust Research Programme, Kilifi, Kenya
| | - James Tuju
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute, Wellcome Trust Research Programme, Kilifi, Kenya; Department of Biotechnology and Biochemistry, Pwani University, Kilifi, Kenya
| | - Kristin Fürle
- Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Micha Rosenkranz
- Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Rinter Kimathi
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute, Wellcome Trust Research Programme, Kilifi, Kenya
| | - Patricia Njuguna
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute, Wellcome Trust Research Programme, Kilifi, Kenya
| | - Mainga Hamaluba
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute, Wellcome Trust Research Programme, Kilifi, Kenya
| | - Melissa C Kapulu
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute, Wellcome Trust Research Programme, Kilifi, Kenya
| | - Roland Frank
- Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Faith H A Osier
- Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany; Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute, Wellcome Trust Research Programme, Kilifi, Kenya; Department of Life Sciences, Imperial College London, London, UK.
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Ogwang R, Murugu L, Nkumama IN, Nyamako L, Kai O, Mwai K, Murungi L, Idro R, Bejon P, Tuju J, Kinyanjui SM, Osier FHA. Bi-isotype immunoglobulins enhance antibody-mediated neutrophil activity against Plasmodium falciparum parasites. Front Immunol 2024; 15:1360220. [PMID: 38650925 PMCID: PMC11033408 DOI: 10.3389/fimmu.2024.1360220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 03/19/2024] [Indexed: 04/25/2024] Open
Abstract
Background Malaria remains a major global health priority, and monoclonal antibodies (mAbs) are emerging as potential new tools to support efforts to control the disease. Recent data suggest that Fc-dependent mechanisms of immunity are important mediators of protection against the blood stages of the infection, but few studies have investigated this in the context of mAbs. We aimed to isolate mAbs agnostic to cognate antigens that target whole merozoites and simultaneously induce potent neutrophil activity measured by the level of reactive oxygen species (ROS) production using an antibody-dependent respiratory burst (ADRB) assay. Methods We used samples from semi-immune adults living in coastal Kenya to isolate mAbs that induce merozoite-specific ADRB activity. We then tested whether modifying the expressed IgG1 isotype to an IgG-IgA Fc region chimera would enhance the level of ADRB activity. Results We isolated a panel of nine mAbs with specificity to whole merozoites. mAb J31 induced ADRB activity in a dose-dependent fashion. Compared to IgG1, our modified antibody IgG-IgA bi-isotype induced higher ADRB activity across all concentrations tested. Further, we observed a negative hook effect at high IgG1 mAb concentrations (i.e., >200 µg/mL), but this was reversed by Fc modification. We identified MSP3.5 as the potential cognate target of mAb J31. Conclusions We demonstrate an approach to engineer mAbs with enhanced ADRB potency against blood-stage parasites.
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Affiliation(s)
- Rodney Ogwang
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- College of Health Sciences, Makerere University, Kampala, Uganda
| | - Lewis Murugu
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Biological Sciences, Pwani University, Kilifi, Kenya
| | - Irene N. Nkumama
- Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Lydia Nyamako
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Oscar Kai
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Kennedy Mwai
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Linda Murungi
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Richard Idro
- College of Health Sciences, Makerere University, Kampala, Uganda
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Philip Bejon
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - James Tuju
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Biological Sciences, Pwani University, Kilifi, Kenya
| | - Sam Muchina Kinyanjui
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Faith H. A. Osier
- Department of Life Sciences, Imperial College London, London, United Kingdom
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Partey FD, Dowuona JNN, Pobee ANA, Walker MR, Aculley B, Prah DA, Ofori MF, Barfod LK. Atypical memory B cell frequency correlates with antibody breadth and function in malaria immune adults. Sci Rep 2024; 14:4888. [PMID: 38418831 PMCID: PMC10902325 DOI: 10.1038/s41598-024-55206-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 02/21/2024] [Indexed: 03/02/2024] Open
Abstract
Clinical immunity to malaria develops slowly after repeated episodes of infection and antibodies are essential in naturally acquired immunity against malaria. However, chronic exposure to malaria has been linked to perturbation in B-cell homeostasis with the accumulation of atypical memory B cells. It is unclear how perturbations in B cell subsets influence antibody breadth, avidity, and function in individuals naturally exposed to malaria. We show that individuals living in high malaria transmission regions in Ghana have higher Plasmodium falciparum merozoite antigen-specific antibodies and an increased antibody breadth score but lower antibody avidities relative to low transmission regions. The frequency of circulating atypical memory B cells is positively associated with an individual's antibody breadth. In vitro growth inhibition is independent of the ability to bind to free merozoites but associated with the breadth of antibody reactivity in an individual. Taken together, our data shows that repeated malaria episodes hamper the development of high avid antibodies which is compensated for by an increase in antibody breadth. Our results provide evidence to reinforce the idea that in regions with high malaria prevalence, repeated malaria infections lead to the broadening of antibody diversity and the continued presence of atypical memory B cell populations.
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Affiliation(s)
| | | | | | - Melanie Rose Walker
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Belinda Aculley
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Diana Ahu Prah
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Legon, Ghana
| | - Michael Fokuo Ofori
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Lea Klingenberg Barfod
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Rathay V, Fürle K, Kiehl V, Ulmer A, Lanzer M, Thomson-Luque R. IgG Subclass Switch in Volunteers Repeatedly Immunized with the Full-Length Plasmodium falciparum Merozoite Surface Protein 1 (MSP1). Vaccines (Basel) 2024; 12:208. [PMID: 38400191 PMCID: PMC10893298 DOI: 10.3390/vaccines12020208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 02/11/2024] [Accepted: 02/13/2024] [Indexed: 02/25/2024] Open
Abstract
Vaccines are highly effective tools against infectious diseases and are also considered necessary in the fight against malaria. Vaccine-induced immunity is frequently mediated by antibodies. We have recently conducted a first-in-human clinical trial featuring SumayaVac-1, a malaria vaccine based on the recombinant, full-length merozoite surface protein 1 (MSP1FL) formulated with GLA-SE as an adjuvant. Vaccination with MSP1FL was safe and elicited sustainable IgG antibody titers that exceeded those observed in semi-immune populations from Africa. Moreover, IgG antibodies stimulated various Fc-mediated effector mechanisms associated with protection against malaria. However, these functionalities gradually waned. Here, we show that the initial two doses of SumayaVac-1 primarily induced the cytophilic subclasses IgG1 and IgG3. Unexpectedly, a shift in the IgG subclass composition occurred following the third and fourth vaccinations. Specifically, there was a progressive transition to IgG4 antibodies, which displayed a reduced capacity to engage in Fc-mediated effector functions and also exhibited increased avidity. In summary, our analysis of antibody responses to MSP1FL vaccination unveils a temporal shift towards noninflammatory IgG4 antibodies. These findings underscore the importance of considering the impact of IgG subclass composition on vaccine-induced immunity, particularly concerning Fc-mediated effector functions. This knowledge is pivotal in guiding the design of optimal vaccination strategies against malaria, informing decision making for future endeavors in this critical field.
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Affiliation(s)
- Veronika Rathay
- Parasitology, Centre for Infectious Diseases, University Hospital Heidelberg, Medical Faculty, Heidelberg University, 69120 Heidelberg, Germany
| | - Kristin Fürle
- Parasitology, Centre for Infectious Diseases, University Hospital Heidelberg, Medical Faculty, Heidelberg University, 69120 Heidelberg, Germany
| | - Viktoria Kiehl
- Parasitology, Centre for Infectious Diseases, University Hospital Heidelberg, Medical Faculty, Heidelberg University, 69120 Heidelberg, Germany
| | - Anne Ulmer
- Parasitology, Centre for Infectious Diseases, University Hospital Heidelberg, Medical Faculty, Heidelberg University, 69120 Heidelberg, Germany
| | - Michael Lanzer
- Parasitology, Centre for Infectious Diseases, University Hospital Heidelberg, Medical Faculty, Heidelberg University, 69120 Heidelberg, Germany
| | - Richard Thomson-Luque
- Parasitology, Centre for Infectious Diseases, University Hospital Heidelberg, Medical Faculty, Heidelberg University, 69120 Heidelberg, Germany
- Sumaya-Biotech GmbH & Co. KG, 69115 Heidelberg, Germany
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6
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Nziza N, Tran TM, DeRiso EA, Dolatshahi S, Herman JD, de Lacerda L, Junqueira C, Lieberman J, Ongoiba A, Doumbo S, Kayentao K, Traore B, Crompton PD, Alter G. Accumulation of Neutrophil Phagocytic Antibody Features Tracks With Naturally Acquired Immunity Against Malaria in Children. J Infect Dis 2023; 228:759-768. [PMID: 37150885 PMCID: PMC10503956 DOI: 10.1093/infdis/jiad115] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 04/21/2023] [Indexed: 05/09/2023] Open
Abstract
BACKGROUND Studies have demonstrated the protective role of antibodies against malaria. Young children are known to be particularly vulnerable to malaria, pointing to the evolution of naturally acquired clinical immunity over time. However, whether changes in antibody functionality track with the acquisition of naturally acquired malaria immunity remains incompletely understood. METHODS Using systems serology, we characterized sporozoite- and merozoite-specific antibody profiles of uninfected Malian children before the malaria season who differed in their ability to control parasitemia and fever following Plasmodium falciparum (Pf) infection. We then assessed the contributions of individual traits to overall clinical outcomes, focusing on the immunodominant sporozoite CSP and merozoite AMA1 and MSP1 antigens. RESULTS Humoral immunity evolved with age, with an expansion of both magnitude and functional quality, particularly within blood-stage phagocytic antibody activity. Moreover, concerning clinical outcomes postinfection, protected children had higher antibody-dependent neutrophil activity along with higher levels of MSP1-specific IgG3 and IgA and CSP-specific IgG3 and IgG4 prior to the malaria season. CONCLUSIONS These data point to the natural evolution of functional humoral immunity to Pf with age and highlight particular antibody Fc-effector profiles associated with the control of malaria in children, providing clues for the design of next-generation vaccines or therapeutics.
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Affiliation(s)
- Nadege Nziza
- Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology, and Harvard University, Cambridge, Massachusetts, USA
| | - Tuan M Tran
- Malaria Infection Biology and Immunity Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
- Division of Infectious Diseases, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Ryan White Center for Pediatric Infectious Disease and Global Health, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Elizabeth A DeRiso
- Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology, and Harvard University, Cambridge, Massachusetts, USA
| | - Sepideh Dolatshahi
- Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology, and Harvard University, Cambridge, Massachusetts, USA
| | - Jonathan D Herman
- Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology, and Harvard University, Cambridge, Massachusetts, USA
| | - Luna de Lacerda
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
- Instituto René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, MG, Brazil
| | - Caroline Junqueira
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
- Instituto René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, MG, Brazil
| | - Judy Lieberman
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Aissata Ongoiba
- Malaria Research and Training Centre, Mali International Center of Excellence in Research, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Safiatou Doumbo
- Malaria Research and Training Centre, Mali International Center of Excellence in Research, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Kassoum Kayentao
- Malaria Research and Training Centre, Mali International Center of Excellence in Research, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Boubacar Traore
- Malaria Research and Training Centre, Mali International Center of Excellence in Research, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Peter D Crompton
- Malaria Infection Biology and Immunity Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Galit Alter
- Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology, and Harvard University, Cambridge, Massachusetts, USA
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Rosenkranz M, Fürle K, Hibbert J, Ulmer A, Ali A, Giese T, Blank A, Haefeli WE, Böhnlein E, Lanzer M, Thomson-Luque R. Multifunctional IgG/IgM antibodies and cellular cytotoxicity are elicited by the full-length MSP1 SumayaVac-1 malaria vaccine. NPJ Vaccines 2023; 8:112. [PMID: 37558673 PMCID: PMC10412566 DOI: 10.1038/s41541-023-00701-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 06/27/2023] [Indexed: 08/11/2023] Open
Abstract
Radical control of malaria likely requires a vaccine that targets both the asymptomatic liver stages and the disease-causing blood stages of the human malaria parasite Plasmodium falciparum. While substantial progress has been made towards liver stage vaccines, the development of a blood stage vaccine is lagging behind. We have recently conducted a first-in-human clinical trial to evaluate the safety and immunogenicity of the recombinant, full-length merozoite surface protein 1 (MSP1FL) formulated with GLA-SE as adjuvant. Here, we show that the vaccine, termed SumayaVac-1, elicited both a humoral and cellular immune response as well as a recall T cell memory. The induced IgG and IgM antibodies were able to stimulate various Fc-mediated effector mechanisms associated with protection against malaria, including phagocytosis, release of reactive oxygen species, production of IFN-γ as well as complement activation and fixation. The multifunctional activity of the humoral immune response remained for at least 6 months after vaccination and was comparable to that of naturally acquired anti-MSP1 antibodies from semi-immune adults from Kenya. We further present evidence of SumayaVac-1 eliciting a recallable cellular cytotoxicity by IFN-γ producing CD8+ T cells. Our study revitalizes MSP1FL as a relevant blood stage vaccine candidate and warrants further evaluation of SumayaVac-1 in a phase II efficacy trial.
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Affiliation(s)
- Micha Rosenkranz
- Center for Infectious Diseases-Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| | - Kristin Fürle
- Center for Infectious Diseases-Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| | - Julia Hibbert
- Center for Infectious Diseases-Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| | - Anne Ulmer
- Center for Infectious Diseases-Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| | - Arin Ali
- Center for Infectious Diseases-Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| | - Thomas Giese
- Institute for Immunology, Heidelberg University Hospital and German Center for Infection Research (DZIF), Heidelberg, Germany
| | - Antje Blank
- Clinical Pharmacology and Pharmacoepidemiology, Heidelberg University Hospital, Heidelberg, Germany
| | - Walter E Haefeli
- Clinical Pharmacology and Pharmacoepidemiology, Heidelberg University Hospital, Heidelberg, Germany
| | | | - Michael Lanzer
- Center for Infectious Diseases-Parasitology, Heidelberg University Hospital, Heidelberg, Germany
| | - Richard Thomson-Luque
- Center for Infectious Diseases-Parasitology, Heidelberg University Hospital, Heidelberg, Germany.
- Sumaya-Biotech GmbH & Co. KG, Heidelberg, Germany.
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8
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Anyona S, Cheng Q, Guo Y, Raballah E, Hurwitz I, Onyango C, Seidenberg P, Schneider K, Lambert C, McMahon B, Ouma C, Perkins D. Entire Expressed Peripheral Blood Transcriptome in Pediatric Severe Malarial Anemia. RESEARCH SQUARE 2023:rs.3.rs-3150748. [PMID: 37503086 PMCID: PMC10371159 DOI: 10.21203/rs.3.rs-3150748/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
This study on severe malarial anemia (SMA: Hb < 6.0 g/dL), a leading global cause of childhood morbidity and mortality, analyzed the entire expressed transcriptome in whole blood from children with non-SMA (Hb ≥ 6.0 g/dL, n = 41) and SMA (n = 25). Analyses revealed 3,420 up-regulated and 3,442 down-regulated transcripts, signifying impairments in host inflammasome activation, cell death, innate immune responses, and cellular stress responses in SMA. Immune cell profiling showed a decreased antigenic and immune priming response in children with SMA, favoring polarization toward cellular proliferation and repair. Enrichment analysis further identified altered neutrophil and autophagy-related processes, consistent with neutrophil degranulation and altered ubiquitination and proteasome degradation. Pathway analyses highlighted SMA-related alterations in cellular homeostasis, signaling, response to environmental cues, and cellular and immune stress responses. Validation with a qRT-PCR array showed strong concordance with the sequencing data. These findings identify key molecular themes in SMA pathogenesis, providing potential targets for new malaria therapies.
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Affiliation(s)
| | | | | | - Evans Raballah
- School of Public Health, Biomedical Sciences and Technology, Masinde Muliro University of Science and Technology
| | - Ivy Hurwitz
- Center for Global Health, University of New Mexico
| | - Clinton Onyango
- School of Public Health and Community Development, Maseno University
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Olewe PK, Awandu SS, Munde EO, Anyona SB, Raballah E, Amolo AS, Ogola S, Ndenga E, Onyango CO, Rochford R, Perkins DJ, Ouma C. Hemoglobinopathies, merozoite surface protein-2 gene polymorphisms, and acquisition of Epstein Barr virus among infants in Western Kenya. BMC Cancer 2023; 23:566. [PMID: 37340364 DOI: 10.1186/s12885-023-11063-2] [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: 10/17/2022] [Accepted: 06/13/2023] [Indexed: 06/22/2023] Open
Abstract
BACKGROUND Epstein Barr virus (EBV)-associated endemic Burkitt's Lymphoma pediatric cancer is associated with morbidity and mortality among children resident in holoendemic Plasmodium falciparum regions in western Kenya. P. falciparum exerts strong selection pressure on sickle cell trait (SCT), alpha thalassemia (-α3.7/αα), glucose-6-phosphate dehydrogenase (G6PD), and merozoite surface protein 2 (MSP-2) variants (FC27, 3D7) that confer reduced malarial disease severity. The current study tested the hypothesis that SCT, (-α3.7/αα), G6PD mutation and (MSP-2) variants (FC27, 3D7) are associated with an early age of EBV acquisition. METHODS Data on infant EBV infection status (< 6 and ≥ 6-12 months of age) was abstracted from a previous longitudinal study. Archived infant DNA (n = 81) and mothers DNA (n = 70) samples were used for genotyping hemoglobinopathies and MSP-2. The presence of MSP-2 genotypes in maternal DNA samples was used to indicate infant in-utero malarial exposure. Genetic variants were determined by TaqMan assays or standard PCR. Group differences were determined by Chi-square or Fisher's analysis. Bivariate regression modeling was used to determine the relationship between the carriage of genetic variants and EBV acquisition. RESULTS EBV acquisition for infants < 6 months was not associated with -α3.7/αα (OR = 1.824, P = 0.354), SCT (OR = 0.897, P = 0.881), or G6PD [Viangchan (871G > A)/Chinese (1024 C > T) (OR = 2.614, P = 0.212)] and [Union (1360 C > T)/Kaiping (1388G > A) (OR = 0.321, P = 0.295)]. There was no relationship between EBV acquisition and in-utero exposure to either FC27 (OR = 0.922, P = 0.914) or 3D7 (OR = 0.933, P = 0.921). In addition, EBV acquisition in infants ≥ 6-12 months also showed no association with -α3.7/αα (OR = 0.681, P = 0.442), SCT (OR = 0.513, P = 0.305), G6PD [(Viangchan (871G > A)/Chinese (1024 C > T) (OR = 0.640, P = 0.677)], [Mahidol (487G > A)/Coimbra (592 C > T) (OR = 0.948, P = 0.940)], [(Union (1360 C > T)/Kaiping (1388G > A) (OR = 1.221, P = 0.768)], African A (OR = 0.278, P = 0.257)], or in utero exposure to either FC27 (OR = 0.780, P = 0.662) or 3D7 (OR = 0.549, P = 0.241). CONCLUSION Although hemoglobinopathies (-α3.7/αα, SCT, and G6PD mutations) and in-utero exposure to MSP-2 were not associated with EBV acquisition in infants 0-12 months, novel G6PD variants were discovered in the population from western Kenya. To establish that the known and novel hemoglobinopathies, and in utero MSP-2 exposure do not confer susceptibility to EBV, future studies with larger sample sizes from multiple sites adopting genome-wide analysis are required.
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Affiliation(s)
- Perez K Olewe
- Department of Biomedical Sciences, School of Health Sciences, Jaramogi Oginga Odinga University of Science and Technology, Bondo, Kenya
- University of New Mexico-Kenyan Global Health Programs Laboratories, Kisumu and Siaya, New Mexico, Kenya
| | - Shehu Shagari Awandu
- Department of Biomedical Sciences, School of Health Sciences, Jaramogi Oginga Odinga University of Science and Technology, Bondo, Kenya
| | - Elly O Munde
- University of New Mexico-Kenyan Global Health Programs Laboratories, Kisumu and Siaya, New Mexico, Kenya
- Department of Clinical Medicine, Kirinyaga University, Kerugoya, Kenya
| | - Samuel B Anyona
- University of New Mexico-Kenyan Global Health Programs Laboratories, Kisumu and Siaya, New Mexico, Kenya
- Department of Medical Biochemistry, School of Medicine, Maseno University, Maseno, Kenya
| | - Evans Raballah
- University of New Mexico-Kenyan Global Health Programs Laboratories, Kisumu and Siaya, New Mexico, Kenya
- Department of Medical Laboratory Sciences, School of Public Health Biomedical Science and Technology, Masinde Muliro University of Science and Technology, Kakamega, Kenya
| | - Asito S Amolo
- Department of Biological Sciences School of Biological, Physical, Mathematics, and Actuarial Sciences, Jaramogi Oginga Odinga University of Science and Technology, Bondo, Kenya
| | - Sidney Ogola
- Kenya Medical Research Institute - CGHR, Kisumu, Kenya
| | - Erick Ndenga
- Department of Biomedical Sciences and Technology, School of Public Health and Community Development, Maseno University, Maseno, Kenya
| | - Clinton O Onyango
- University of New Mexico-Kenyan Global Health Programs Laboratories, Kisumu and Siaya, New Mexico, Kenya
| | | | - Douglas J Perkins
- University of New Mexico-Kenyan Global Health Programs Laboratories, Kisumu and Siaya, New Mexico, Kenya
- Center for Global Health, Internal Medicine, University of New Mexico, New Mexico, NM, USA
| | - Collins Ouma
- University of New Mexico-Kenyan Global Health Programs Laboratories, Kisumu and Siaya, New Mexico, Kenya.
- Department of Biomedical Sciences and Technology, School of Public Health and Community Development, Maseno University, Maseno, Kenya.
- Research and Innovations, Maseno University, Kisumu-Busia Road Private Bag, Maseno, Kenya.
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10
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Jahnmatz P, Nyabundi D, Sundling C, Widman L, Mwacharo J, Musyoki J, Otieno E, Ahlborg N, Bejon P, Ndungu FM, Färnert A. Plasmodium falciparum-Specific Memory B-Cell and Antibody Responses Are Associated With Immunity in Children Living in an Endemic Area of Kenya. Front Immunol 2022; 13:799306. [PMID: 35355994 PMCID: PMC8959630 DOI: 10.3389/fimmu.2022.799306] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 02/16/2022] [Indexed: 11/14/2022] Open
Abstract
Identifying the mechanism of naturally acquired immunity against Plasmodium falciparum malaria could contribute to the design of effective malaria vaccines. Using a recently developed multiplexed FluoroSpot assay, we assessed cross-sectional pre-existing memory B-cells (MBCs) and antibody responses against six well known P. falciparum antigens (MSP-119, MSP-2 (3D7), MSP-2 (FC27), MSP-3, AMA-1 and CSP) and measured their associations with previous infections and time to clinical malaria in the ensuing malaria season in Kenyan children. These children were under active weekly surveillance for malaria as part of a long-term longitudinal malaria immunology cohort study, where they are recruited from birth. After performing Cox regression analysis, we found that children with a breadth of three or more antigen-specific MBC or antibody responses at the baseline had a reduced risk for malaria in the ensuing P. falciparum transmission season. Specifically, MBC responses against AMA-1, MSP-2 (3D7) and MSP-3, as well as antibody responses to MSP-2 (3D7) and MSP-3 were prospectively associated with a reduced risk for malaria. The magnitude or breadth of MBC responses were however not correlated with the cumulative number of malaria episodes since birth. We conclude that increased breadth for merozoite antigen-specific MBC and antibody responses is associated with protection against malaria.
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Affiliation(s)
- Peter Jahnmatz
- Division of Infectious Diseases, Department of Medicine Solna and Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
- Mabtech AB, Nacka Strand, Sweden
| | - Diana Nyabundi
- KEMRI - Wellcome Research Programme/Centre for Geographical Medicine Research (Coast), Kilifi, Kenya
| | - Christopher Sundling
- Division of Infectious Diseases, Department of Medicine Solna and Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
- Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Linnea Widman
- Division of Biostatistics, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Jedidah Mwacharo
- KEMRI - Wellcome Research Programme/Centre for Geographical Medicine Research (Coast), Kilifi, Kenya
| | - Jennifer Musyoki
- KEMRI - Wellcome Research Programme/Centre for Geographical Medicine Research (Coast), Kilifi, Kenya
| | - Edward Otieno
- KEMRI - Wellcome Research Programme/Centre for Geographical Medicine Research (Coast), Kilifi, Kenya
| | - Niklas Ahlborg
- Mabtech AB, Nacka Strand, Sweden
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Philip Bejon
- KEMRI - Wellcome Research Programme/Centre for Geographical Medicine Research (Coast), Kilifi, Kenya
| | - Francis M. Ndungu
- Division of Infectious Diseases, Department of Medicine Solna and Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
- KEMRI - Wellcome Research Programme/Centre for Geographical Medicine Research (Coast), Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom
| | - Anna Färnert
- Division of Infectious Diseases, Department of Medicine Solna and Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
- Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
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11
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Addy JW, Bediako Y, Ndungu FM, Valetta JJ, Reid AJ, Mwacharo J, Ngoi JM, Wambua J, Otieno E, Musyoki J, Said K, Berriman M, Marsh K, Bejon P, Recker M, Langhorne J. 10-year longitudinal study of malaria in children: Insights into acquisition and maintenance of naturally acquired immunity. Wellcome Open Res 2022; 6:79. [PMID: 35141425 PMCID: PMC8822141 DOI: 10.12688/wellcomeopenres.16562.3] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/31/2022] [Indexed: 01/26/2023] Open
Abstract
Background: Studies of long-term malaria cohorts have provided essential insights into how Plasmodium falciparum interacts with humans, and influences the development of antimalarial immunity. Immunity to malaria is acquired gradually after multiple infections, some of which present with clinical symptoms. However, there is considerable variation in the number of clinical episodes experienced by children of the same age within the same cohort. Understanding this variation in clinical symptoms and how it relates to the development of naturally acquired immunity is crucial in identifying how and when some children stop experiencing further malaria episodes. Where variability in clinical episodes may result from different rates of acquisition of immunity, or from variable exposure to the parasite. Methods: Using data from a longitudinal cohort of children residing in an area of moderate P. falciparum transmission in Kilifi district, Kenya, we fitted cumulative episode curves as monotonic-increasing splines, to 56 children under surveillance for malaria from the age of 5 to 15. Results: There was large variability in the accumulation of numbers of clinical malaria episodes experienced by the children, despite being of similar age and living in the same general location. One group of children from a particular sub-region of the cohort stopped accumulating clinical malaria episodes earlier than other children in the study. Despite lack of further clinical episodes of malaria, these children had higher asymptomatic parasite densities and higher antibody titres to a panel of P. falciparum blood-stage antigens. Conclusions: This suggests development of clinical immunity rather than lack of exposure to the parasite, and supports the view that this immunity to malaria disease is maintained by a greater exposure to P. falciparum, and thus higher parasite burdens. Our study illustrates the complexity of anti-malaria immunity and underscores the need for analyses which can sufficiently reflect the heterogeneity within endemic populations.
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Affiliation(s)
- John W.G. Addy
- Malaria Immunology Laboratory, Francis Crick Institute, London, UK
| | - Yaw Bediako
- Malaria Immunology Laboratory, Francis Crick Institute, London, UK
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | | | - John Joseph Valetta
- School of Mathematics and Statistics, University of St Andrews, St Andrews, UK
| | - Adam J. Reid
- Parasite Genomics, Wellcome Sanger Institute, Hixton, UK
| | | | | | - Joshua Wambua
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | - Edward Otieno
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Khadija Said
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Kevin Marsh
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Philip Bejon
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | - Mario Recker
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, UK
| | - Jean Langhorne
- Malaria Immunology Laboratory, Francis Crick Institute, London, UK
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12
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Kapulu MC, Kimani D, Njuguna P, Hamaluba M, Otieno E, Kimathi R, Tuju J, Sim BKL, Abdi AI, Abebe Y, Bejon P, Billingsley PF, Bull PC, de Laurent Z, Hoffman SL, James ER, Kariuki S, Kinyanjui S, Kivisi C, Makale J, Marsh K, Mohammed KS, Mosobo M, Musembi J, Musyoki J, Muthui M, Mwacharo J, Mwai K, Ngoi JM, Ngoto O, Nkumama I, Ndungu F, Odera D, Ogutu B, Olewe F, Omuoyo D, Ong’echa J, Osier F, Richie TL, Shangala J, Wambua J, Williams TN. Controlled human malaria infection (CHMI) outcomes in Kenyan adults is associated with prior history of malaria exposure and anti-schizont antibody response. BMC Infect Dis 2022; 22:86. [PMID: 35073864 PMCID: PMC8785382 DOI: 10.1186/s12879-022-07044-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 01/11/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Individuals living in endemic areas acquire immunity to malaria following repeated parasite exposure. We sought to assess the controlled human malaria infection (CHMI) model as a means of studying naturally acquired immunity in Kenyan adults with varying malaria exposure.
Methods
We analysed data from 142 Kenyan adults from three locations representing distinct areas of malaria endemicity (Ahero, Kilifi North and Kilifi South) enrolled in a CHMI study with Plasmodium falciparum sporozoites NF54 strain (Sanaria® PfSPZ Challenge). To identify the in vivo outcomes that most closely reflected naturally acquired immunity, parameters based on qPCR measurements were compared with anti-schizont antibody levels and residence as proxy markers of naturally acquired immunity.
Results
Time to endpoint correlated more closely with anti-schizont antibodies and location of residence than other parasite parameters such as growth rate or mean parasite density. Compared to observational field-based studies in children where 0.8% of the variability in malaria outcome was observed to be explained by anti-schizont antibodies, in the CHMI model the dichotomized anti-schizont antibodies explained 17% of the variability.
Conclusions
The CHMI model is highly effective in studying markers of naturally acquired immunity to malaria.
Trial registration Clinicaltrials.gov number NCT02739763. Registered 15 April 2016
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13
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Muthui MK, Takashima E, Omondi BR, Kinya C, Muasya WI, Nagaoka H, Mwai KW, Orindi B, Wambua J, Bousema T, Drakeley C, Blagborough AM, Marsh K, Bejon P, Kapulu MC. Characterization of Naturally Acquired Immunity to a Panel of Antigens Expressed in Mature P. falciparum Gametocytes. Front Cell Infect Microbiol 2021; 11:774537. [PMID: 34869075 PMCID: PMC8633105 DOI: 10.3389/fcimb.2021.774537] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Accepted: 10/25/2021] [Indexed: 11/13/2022] Open
Abstract
Introduction Naturally acquired immune responses against antigens expressed on the surface of mature gametocytes develop in individuals living in malaria-endemic areas. Evidence suggests that such anti-gametocyte immunity can block the development of the parasite in the mosquito, thus playing a role in interrupting transmission. A better comprehension of naturally acquired immunity to these gametocyte antigens can aid the development of transmission-blocking vaccines and improve our understanding of the human infectious reservoir. Methods Antigens expressed on the surface of mature gametocytes that had not previously been widely studied for evidence of naturally acquired immunity were identified for protein expression alongside Pfs230-C using either the mammalian HEK293E or the wheat germ cell-free expression systems. Where there was sequence variation in the candidate antigens (3D7 vs a clinical isolate PfKE04), both variants were expressed. ELISA was used to assess antibody responses against these antigens, as well as against crude stage V gametocyte extract (GE) and AMA1 using archived plasma samples from individuals recruited to participate in malaria cohort studies. We analyzed antibody levels (estimated from optical density units using a standardized ELISA) and seroprevalence (defined as antibody levels greater than three standard deviations above the mean levels of a pool of malaria naïve sera). We described the dynamics of antibody responses to these antigens by identifying factors predictive of antibody levels using linear regression models. Results Of the 25 antigens selected, seven antigens were produced successfully as recombinant proteins, with one variant antigen, giving a total of eight proteins for evaluation. Antibodies to the candidate antigens were detectable in the study population (N = 216), with seroprevalence ranging from 37.0% (95% CI: 30.6%, 43.9%) for PSOP1 to 77.8% (95% CI: 71.6%, 83.1%) for G377 (3D7 variant). Responses to AMA1 and GE were more prevalent than those to the gametocyte proteins at 87.9% (95% CI: 82.8%, 91.9%) and 88.3% (95% CI: 83.1%, 92.4%), respectively. Additionally, both antibody levels and breadth of antibody responses were associated with age and concurrent parasitaemia. Conclusion Age and concurrent parasitaemia remain important determinants of naturally acquired immunity to gametocyte antigens. Furthermore, we identify novel candidates for transmission-blocking activity evaluation.
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Affiliation(s)
- Michelle K Muthui
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya
| | - Eizo Takashima
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - Brian R Omondi
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya
| | - Christine Kinya
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya
| | - William I Muasya
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya
| | - Hikaru Nagaoka
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - Kennedy W Mwai
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya.,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Benedict Orindi
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya
| | - Juliana Wambua
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Andrew M Blagborough
- Division of Microbiology and Parasitology, Department of Pathology, Cambridge University, Tennis Court Road, Cambridge, United Kingdom
| | - Kevin Marsh
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Philip Bejon
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Melissa C Kapulu
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
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14
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Addy JW, Bediako Y, Ndungu FM, Valetta JJ, Reid AJ, Mwacharo J, Ngoi JM, Wambua J, Otieno E, Musyoki J, Said K, Berriman M, Marsh K, Bejon P, Recker M, Langhorne J. 10-year longitudinal study of malaria in children: Insights into acquisition and maintenance of naturally acquired immunity. Wellcome Open Res 2021; 6:79. [PMID: 35141425 PMCID: PMC8822141 DOI: 10.12688/wellcomeopenres.16562.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2021] [Indexed: 01/26/2023] Open
Abstract
Background: Studies of long-term malaria cohorts have provided essential insights into how Plasmodium falciparum interacts with humans, and influences the development of antimalarial immunity. Immunity to malaria is acquired gradually after multiple infections, some of which present with clinical symptoms. However, there is considerable variation in the number of clinical episodes experienced by children of the same age within the same cohort. Understanding this variation in clinical symptoms and how it relates to the development of naturally acquired immunity is crucial in identifying how and when some children stop experiencing further malaria episodes. Where variability in clinical episodes may result from different rates of acquisition of immunity, or from variable exposure to the parasite. Methods: Using data from a longitudinal cohort of children residing in an area of moderate P. falciparum transmission in Kilifi district, Kenya, we fitted cumulative episode curves as monotonic-increasing splines, to 56 children under surveillance for malaria from the age of 5 to 15. Results: There was large variability in the accumulation of numbers of clinical malaria episodes experienced by the children, despite being of similar age and living in the same general location. One group of children from a particular sub-region of the cohort stopped accumulating clinical malaria episodes earlier than other children in the study. Despite lack of further clinical episodes of malaria, these children had higher asymptomatic parasite densities and higher antibody titres to a panel of P. falciparum blood-stage antigens. Conclusions: This suggests development of clinical immunity rather than lack of exposure to the parasite, and supports the view that this immunity to malaria disease is maintained by a greater exposure to P. falciparum, and thus higher parasite burdens. Our study illustrates the complexity of anti-malaria immunity and underscores the need for analyses which can sufficiently reflect the heterogeneity within endemic populations.
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Affiliation(s)
- John W.G. Addy
- Malaria Immunology Laboratory, Francis Crick Institute, London, UK
| | - Yaw Bediako
- Malaria Immunology Laboratory, Francis Crick Institute, London, UK
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | | | - John Joseph Valetta
- School of Mathematics and Statistics, University of St Andrews, St Andrews, UK
| | - Adam J. Reid
- Parasite Genomics, Wellcome Sanger Institute, Hixton, UK
| | | | | | - Joshua Wambua
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | - Edward Otieno
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Khadija Said
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Kevin Marsh
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Philip Bejon
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | - Mario Recker
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, UK
| | - Jean Langhorne
- Malaria Immunology Laboratory, Francis Crick Institute, London, UK
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15
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Isebe TI, Bargul JL, Gichuki BM, Njunge JM, Tuju J, Rono MK. Molecular characterization of Plasmodium falciparum PHISTb proteins as potential targets of naturally-acquired immunity against malaria. Wellcome Open Res 2021. [DOI: 10.12688/wellcomeopenres.15919.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Background: Plasmodium falciparum causes the deadliest form of malaria in humans. Upon infection, the host’s infected red blood cells (iRBCs) are remodelled by exported parasite proteins to provide a niche for parasite development and maturation. Methods: Here we analysed the role of three PHISTb proteins Pf3D7_0532400, Pf3D7_1401600, and Pf3D7_1102500 by expressing recombinant proteins and evaluated antibody responses against these proteins using immune sera from malaria-exposed individuals from Kenya and The Gambia in Africa. Results: Children and adults from malaria-endemic regions recognized the three PHISTb proteins. Responses against PHISTb proteins varied with malaria transmission intensity in three different geographical sites in Kenya (Siaya and Takaungu) and The Gambia (Sukuta). Antibody responses against PHISTb antigens Pf3D7_1102500 and Pf3D7_1401600 were higher in Sukuta, a low transmission region in Gambia, compared to Siaya, a high transmission region in western Kenya, unlike Pf3D7_0532400. Anti-PHIST responses indicate negative correlation between antibody levels and malaria transmission intensity for Pf3D7_1102500 and Pf3D7_1401600. We report a correlation in antibody responses between schizont and gametocyte extract, but this is not statistically significant (cor=0.102, p=0.2851, CI=95%) and, Pf3D7_0532400 (cor=0.11, p=0.249, CI=95%) and Pf3D7_1401600 (cor=0.02, p=0.7968, CI=95%). We report a negative correlation in antibody responses between schizont and Pf3D7_1102500 (cor=-0.008, p=0.9348, CI=95%). There is a correlation between gametocyte extract and Pf3D7_1401600 (cor=-0.0402, p=0.6735, CI=95%), Pf3D7_1102500 (cor=0.0758, p=0.4271, CI=95%) and Pf3D7_0532400 (cor=0.155, p=0.1028, CI=95%). Acquisition of anti-PHIST antibodies correlates with exposure to malaria for Pf3D7_0532400 (p=0.009) but not Pf3D7_1102500 and Pf3D7_1401600 (p=0.507 and p=0.15, respectively, CI=95%). Children aged below 2 years had the lowest antibody levels which do not correlate with age differences. Conclusions: Collectively, these findings provide evidence of natural immunity against PHISTb antigens that varies with level of malaria exposure and underscore their potential as possible serological markers to P. falciparum infection aimed at contributing to malaria control through vaccine development.
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16
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Addy JW, Bediako Y, Ndungu FM, Valetta JJ, Reid AJ, Mwacharo J, Ngoi JM, Wambua J, Otieno E, Musyoki J, Said K, Berriman M, Marsh K, Bejon P, Recker M, Langhorne J. 10-year longitudinal study of malaria in children: Insights into acquisition and maintenance of naturally acquired immunity. Wellcome Open Res 2021; 6:79. [PMID: 35141425 PMCID: PMC8822141 DOI: 10.12688/wellcomeopenres.16562.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/26/2021] [Indexed: 01/26/2023] Open
Abstract
Background: Studies of long-term malaria cohorts have provided essential insights into how Plasmodium falciparum interacts with humans, and influences the development of antimalarial immunity. Immunity to malaria is acquired gradually after multiple infections, some of which present with clinical symptoms. However, there is considerable variation in the number of clinical episodes experienced by children of the same age within the same cohort. Understanding this variation in clinical symptoms and how it relates to the development of naturally acquired immunity is crucial in identifying how and when some children stop experiencing further malaria episodes. Where variability in clinical episodes may result from different rates of acquisition of immunity, or from variable exposure to the parasite. Methods: Using data from a longitudinal cohort of children residing in an area of moderate P. falciparum transmission in Kilifi district, Kenya, we fitted cumulative episode curves as monotonic-increasing splines, to 56 children under surveillance for malaria from the age of 5 to 15. Results: There was large variability in the accumulation of numbers of clinical malaria episodes experienced by the children, despite being of similar age and living in the same general location. One group of children from a particular sub-region of the cohort stopped accumulating clinical malaria episodes earlier than other children in the study. Despite lack of further clinical episodes of malaria, these children had higher asymptomatic parasite densities and higher antibody titres to a panel of P. falciparum blood-stage antigens. Conclusions: This suggests development of clinical immunity rather than lack of exposure to the parasite, and supports the view that this immunity to malaria disease is maintained by a greater exposure to P. falciparum, and thus higher parasite burdens. Our study illustrates the complexity of anti-malaria immunity and underscores the need for analyses which can sufficiently reflect the heterogeneity within endemic populations.
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Affiliation(s)
- John W.G. Addy
- Malaria Immunology Laboratory, Francis Crick Institute, London, UK
| | - Yaw Bediako
- Malaria Immunology Laboratory, Francis Crick Institute, London, UK
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | | | - John Joseph Valetta
- School of Mathematics and Statistics, University of St Andrews, St Andrews, UK
| | - Adam J. Reid
- Parasite Genomics, Wellcome Sanger Institute, Hixton, UK
| | | | | | - Joshua Wambua
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | - Edward Otieno
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Khadija Said
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Kevin Marsh
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Philip Bejon
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | - Mario Recker
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, UK
| | - Jean Langhorne
- Malaria Immunology Laboratory, Francis Crick Institute, London, UK
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17
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Gonzales SJ, Reyes RA, Braddom AE, Batugedara G, Bol S, Bunnik EM. Naturally Acquired Humoral Immunity Against Plasmodium falciparum Malaria. Front Immunol 2020; 11:594653. [PMID: 33193447 PMCID: PMC7658415 DOI: 10.3389/fimmu.2020.594653] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 10/07/2020] [Indexed: 12/18/2022] Open
Abstract
Malaria remains a significant contributor to the global burden of disease, with around 40% of the world's population at risk of Plasmodium infections. The development of an effective vaccine against the malaria parasite would mark a breakthrough in the fight to eradicate the disease. Over time, natural infection elicits a robust immune response against the blood stage of the parasite, providing protection against malaria. In recent years, we have gained valuable insight into the mechanisms by which IgG acts to prevent pathology and inhibit parasite replication, as well as the potential role of immunoglobulin M (IgM) in these processes. Here, we discuss recent advances in our understanding of the mechanisms, acquisition, and maintenance of naturally acquired immunity, and the relevance of these discoveries for the development of a potential vaccine against the blood stage of Plasmodium falciparum.
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Affiliation(s)
| | | | | | | | | | - Evelien M. Bunnik
- Department of Microbiology, Immunology and Molecular Genetics, Long School of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
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18
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Isebe TI, Bargul JL, Gichuki BM, Njunge JM, Tuju J, Rono MK. Molecular characterization of Plasmodium falciparum PHISTb proteins as potential targets of naturally-acquired immunity against malaria. Wellcome Open Res 2020. [DOI: 10.12688/wellcomeopenres.15919.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Background: Plasmodium falciparum causes the deadliest form of malaria in humans. Upon infection, the host’s infected red blood cells (iRBCs) are remodelled by exported parasite proteins in order to provide a niche for parasite development and maturation. Methods: Here we analysed the role of three PHISTb proteins Pf3D7_0532400, Pf3D7_1401600, and Pf3D7_1102500 by expressing recombinant proteins and evaluated antibody responses against these proteins using immune sera from malaria-exposed individuals from Kenya and The Gambia in Africa. Results: Our findings show that children and adults from malaria-endemic regions recognized the three PHISTb proteins. Responses against the PHISTb proteins varied with malaria transmission intensity in three different geographical sites in Kenya (Siaya and Takaungu) and The Gambia (Sukuta). Antibody responses against PHISTb antigens Pf3D7_1102500 and Pf3D7_1401600 were higher in Sukuta, a low transmission region in the Gambia, as compared to Siaya, a high transmission region in western Kenya, unlike Pf3D7_0532400. Anti-PHIST responses show a negative correlation between antibody levels and malaria transmission intensity for two PHIST antigens, Pf3D7_1102500 and Pf3D7_1401600. However, we report a correlation in antibody responses between schizont extract and Pf3D7_0532400 (p=0.00582). Acquisition of anti-PHIST antibodies was correlated with exposure to malaria for PHISTb protein Pf3D7_0532400 (p=0.009) but not the other PHIST antigens Pf3D7_1102500 and Pf3D7_1401600 (p=0.507 and p=0.15, respectively, CI=95%). Children aged below 2 years had the lowest antibody levels, but the responses do not correlate with age differences. Conclusions: Collectively, these findings provide evidence of natural immunity against PHISTb antigens that varies with level of malaria exposure and underscore potential for these parasite antigens as possible serological markers to P. falciparum infection aimed at contributing to malaria control through vaccine development.
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19
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Kana IH, Singh SK, Garcia-Senosiain A, Dodoo D, Singh S, Adu B, Theisen M. Breadth of Functional Antibodies Is Associated With Plasmodium falciparum Merozoite Phagocytosis and Protection Against Febrile Malaria. J Infect Dis 2020; 220:275-284. [PMID: 30820557 DOI: 10.1093/infdis/jiz088] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 02/26/2019] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The specific targets of functional antibodies against Plasmodium falciparum merozoites remain largely unexplored and, more importantly, their relevance to naturally acquired immunity in longitudinal cohort studies (LCSs) is yet to be tested. METHODS Functionality of immunoglobulin G (IgG) antibodies against 24 merozoite antigens was determined at the baseline of an LCS in Ghana using a bead-based opsonic phagocytosis assay (BPA). Antigen-specific IgG3 subclass antibodies were quantified in the same samples by the Luminex multiplex system. RESULTS A wide range of BPA activity was observed across the different antigens. High BPA responses of nMSP3K1, GLURP-R2, MSP23D7, MSP119k, and PfRh2-2030 coupled beads were significantly associated with a higher probability of children not experiencing febrile malaria. Children with high breadth of functional antibodies against these antigens together with cMSP33D7 had a significantly reduced risk of febrile malaria (adjusted hazard ratio, 0.36 [95% confidence interval, .18-.72]; P = .004). Five of the 6 BPA activities significantly (likelihood ratio rest, P ≤ .05) contributed to the protective immunity observed with the IgG3 antibodies. CONCLUSIONS The development of BPA allowed profiling of functional antibodies in an LCS. Identification of targets of opsonic phagocytosis may have implications in the development of a subunit malaria vaccine.
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Affiliation(s)
- Ikhlaq Hussain Kana
- Department for Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark.,Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Susheel Kumar Singh
- Department for Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark.,Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Asier Garcia-Senosiain
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Daniel Dodoo
- Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon
| | | | - Bright Adu
- Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon
| | - Michael Theisen
- Department for Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark.,Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
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20
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Aitken EH, Mahanty S, Rogerson SJ. Antibody effector functions in malaria and other parasitic diseases: a few needles and many haystacks. Immunol Cell Biol 2020; 98:264-275. [DOI: 10.1111/imcb.12320] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 01/02/2020] [Accepted: 01/28/2020] [Indexed: 12/13/2022]
Affiliation(s)
- Elizabeth H Aitken
- Department of Medicine The Doherty Institute The University of Melbourne 792 Elizabeth Street Melbourne VIC 3000 Australia
| | - Siddhartha Mahanty
- Department of Medicine The Doherty Institute The University of Melbourne 792 Elizabeth Street Melbourne VIC 3000 Australia
| | - Stephen J Rogerson
- Department of Medicine The Doherty Institute The University of Melbourne 792 Elizabeth Street Melbourne VIC 3000 Australia
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21
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Blank A, Fürle K, Jäschke A, Mikus G, Lehmann M, Hüsing J, Heiss K, Giese T, Carter D, Böhnlein E, Lanzer M, Haefeli WE, Bujard H. Immunization with full-length Plasmodium falciparum merozoite surface protein 1 is safe and elicits functional cytophilic antibodies in a randomized first-in-human trial. NPJ Vaccines 2020; 5:10. [PMID: 32025341 PMCID: PMC6994672 DOI: 10.1038/s41541-020-0160-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 01/14/2020] [Indexed: 12/20/2022] Open
Abstract
A vaccine remains a priority in the global fight against malaria. Here, we report on a single-center, randomized, double-blind, placebo and adjuvant-controlled, dose escalation phase 1a safety and immunogenicity clinical trial of full-length Plasmodium falciparum merozoite surface protein 1 (MSP1) in combination with GLA-SE adjuvant. Thirty-two healthy volunteers were vaccinated at least three times with MSP1 plus adjuvant, adjuvant alone, or placebo (24:4:4) to evaluate the safety and immunogenicity. MSP1 was safe, well tolerated and immunogenic, with all vaccinees sero-converting independent of the dose. The MSP1-specific IgG and IgM titers persisted above levels found in malaria semi-immune humans for at least 6 months after the last immunization. The antibodies were variant- and strain-transcending and stimulated respiratory activity in granulocytes. Furthermore, full-length MSP1 induced memory T-cells. Our findings encourage challenge studies as the next step to evaluate the efficacy of full-length MSP1 as a vaccine candidate against falciparum malaria (EudraCT 2016-002463-33).
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Affiliation(s)
- Antje Blank
- Klinische Pharmakologie und Pharmakoepidemiologie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| | - Kristin Fürle
- Center of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Anja Jäschke
- Center of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Gerd Mikus
- Klinische Pharmakologie und Pharmakoepidemiologie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| | - Monika Lehmann
- Koordinierungszentrum für Klinische Studien (KKS), Universitätsklinikum Heidelberg, Im Neuenheimer Feld 130.3, 69120 Heidelberg, Germany
| | - Johannes Hüsing
- Koordinierungszentrum für Klinische Studien (KKS), Universitätsklinikum Heidelberg, Im Neuenheimer Feld 130.3, 69120 Heidelberg, Germany
| | - Kirsten Heiss
- PEPperPRINT GmbH, Rischerstrasse 12, 69123 Heidelberg, Germany
| | - Thomas Giese
- Institut für Immunologie, Universitätsklinikum Heidelberg und Deutsches Zentrum für Infektionsforschung (DZIF) Standort Heidelberg, Im Neuenheimer Feld 305, 69120 Heidelberg, Germany
| | - Darrick Carter
- PAI Life Sciences, 1616 Eastlake Ave E, Suite 550, Seattle, WA 98102 USA
| | - Ernst Böhnlein
- Sumaya Biotech GmbH & Co. KG, Im Neuenheimer Feld 582, 69120 Heidelberg, Germany
| | - Michael Lanzer
- Center of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Walter E. Haefeli
- Klinische Pharmakologie und Pharmakoepidemiologie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| | - Hermann Bujard
- Sumaya Biotech GmbH & Co. KG, Im Neuenheimer Feld 582, 69120 Heidelberg, Germany
- Zentrum für Molekulare Biologie Heidelberg, Universität Heidelberg, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
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22
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Kapulu MC, Njuguna P, Hamaluba MM. Controlled Human Malaria Infection in Semi-Immune Kenyan Adults (CHMI-SIKA): a study protocol to investigate in vivo Plasmodium falciparum malaria parasite growth in the context of pre-existing immunity. Wellcome Open Res 2019; 3:155. [PMID: 31803847 PMCID: PMC6871356 DOI: 10.12688/wellcomeopenres.14909.2] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/30/2019] [Indexed: 01/09/2023] Open
Abstract
Malaria remains a major public health burden despite approval for implementation of a partially effective pre-erythrocytic malaria vaccine. There is an urgent need to accelerate development of a more effective multi-stage vaccine. Adults in malaria endemic areas may have substantial immunity provided by responses to the blood stages of malaria parasites, but field trials conducted on several blood-stage vaccines have not shown high levels of efficacy. We will use the controlled human malaria infection (CHMI) models with malaria-exposed volunteers to identify correlations between immune responses and parasite growth rates in vivo. Immune responses more strongly associated with control of parasite growth should be prioritized to accelerate malaria vaccine development. We aim to recruit up to 200 healthy adult volunteers from areas of differing malaria transmission in Kenya, and after confirming their health status through clinical examination and routine haematology and biochemistry, we will comprehensively characterize immunity to malaria using >100 blood-stage antigens. We will administer 3,200 aseptic, purified, cryopreserved Plasmodium falciparum sporozoites (PfSPZ Challenge) by direct venous inoculation. Serial quantitative polymerase chain reaction to measure parasite growth rate in vivo will be undertaken. Clinical and laboratory monitoring will be undertaken to ensure volunteer safety. In addition, we will also explore the perceptions and experiences of volunteers and other stakeholders in participating in a malaria volunteer infection study. Serum, plasma, peripheral blood mononuclear cells and whole blood will be stored to allow a comprehensive assessment of adaptive and innate host immunity. We will use CHMI in semi-immune adult volunteers to relate parasite growth outcomes with antibody responses and other markers of host immunity. Registration: ClinicalTrials.gov identifier NCT02739763.
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Affiliation(s)
- Melissa C. Kapulu
- KEMRI-Wellcome Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University Oxford, Oxford, UK
| | | | | | - CHMI-SIKA Study Team
- KEMRI-Wellcome Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University Oxford, Oxford, UK
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23
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Wang YN, Lin M, Liang XY, Chen JT, Xie DD, Wang YL, Ehapo CS, Eyi UM, Huang HY, Wu JL, Xu DY, Chen ZM, Cao YL, Chen HB. Natural selection and genetic diversity of domain I of Plasmodium falciparum apical membrane antigen-1 on Bioko Island. Malar J 2019; 18:317. [PMID: 31533747 PMCID: PMC6751645 DOI: 10.1186/s12936-019-2948-y] [Citation(s) in RCA: 7] [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: 04/17/2019] [Accepted: 09/06/2019] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Plasmodium falciparum apical membrane antigen-1 (PfAMA-1) is a promising candidate antigen for a blood-stage malaria vaccine. However, antigenic variation and diversity of PfAMA-1 are still major problems to design a universal malaria vaccine based on this antigen, especially against domain I (DI). Detail understanding of the PfAMA-1 gene polymorphism can provide useful information on this potential vaccine component. Here, general characteristics of genetic structure and the effect of natural selection of DIs among Bioko P. falciparum isolates were analysed. METHODS 214 blood samples were collected from Bioko Island patients with P. falciparum malaria between 2011 and 2017. A fragment spanning DI of PfAMA-1 was amplified by nested polymerase chain reaction and sequenced. Polymorphic characteristics and the effect of natural selection were analysed using MEGA 5.0, DnaSP 6.0 and Popart programs. Genetic diversity in 576 global PfAMA-1 DIs were also analysed. Protein function prediction of new amino acid mutation sites was performed using PolyPhen-2 program. RESULTS 131 different haplotypes of PfAMA-1 were identified in 214 Bioko Island P. falciparum isolates. Most amino acid changes identified on Bioko Island were found in C1L. 32 amino acid changes identified in PfAMA-1 sequences from Bioko Island were found in predicted RBC-binding sites, B cell epitopes or IUR regions. Overall patterns of amino acid changes of Bioko PfAMA-1 DIs were similar to those in global PfAMA-1 isolates. Differential amino acid substitution frequencies were observed for samples from different geographical regions. Eight new amino acid changes of Bioko island isolates were also identified and their three-dimensional protein structural consequences were predicted. Evidence for natural selection and recombination event were observed in global isolates. CONCLUSIONS Patterns of nucleotide diversity and amino acid polymorphisms of Bioko Island isolates were similar to those of global PfAMA-1 DIs. Balancing natural selection across DIs might play a major role in generating genetic diversity in global isolates. Most amino acid changes in DIs occurred in predicted B-cell epitopes. Novel sites mapped on a three dimensional structure of PfAMA-1 showed that these regions were located at the corner. These results may provide significant value in the design of a malaria vaccine based on this antigen.
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Affiliation(s)
- Ya-Nan Wang
- Department of Histology and Embryology, Shantou University Medical College, Shantou, Guangdong, People's Republic of China
| | - Min Lin
- School of Food Engineering and Biotechnology, Hanshan Normal University, Chaozhou, Guangdong, People's Republic of China
| | - Xue-Yan Liang
- Department of Histology and Embryology, Shantou University Medical College, Shantou, Guangdong, People's Republic of China
- School of Food Engineering and Biotechnology, Hanshan Normal University, Chaozhou, Guangdong, People's Republic of China
| | - Jiang-Tao Chen
- Laboratory Medical Centre, Huizhou Municipal Central Hospital, Huizhou, Guangdong, People's Republic of China
- The Chinese Medical Aid Team to the Republic of Equatorial Guinea, Guangzhou, Guangdong, People's Republic of China
| | - Dong-De Xie
- Laboratory Medical Centre, Huizhou Municipal Central Hospital, Huizhou, Guangdong, People's Republic of China
| | - Yu-Ling Wang
- Laboratory Medical Centre, Huizhou Municipal Central Hospital, Huizhou, Guangdong, People's Republic of China
| | - Carlos Salas Ehapo
- Department of Medical Laboratory, Malabo Regional Hospital, Malabo, Equatorial Guinea
| | - Urbano Monsuy Eyi
- Department of Medical Laboratory, Malabo Regional Hospital, Malabo, Equatorial Guinea
| | - Hui-Ying Huang
- Department of Histology and Embryology, Shantou University Medical College, Shantou, Guangdong, People's Republic of China
- School of Food Engineering and Biotechnology, Hanshan Normal University, Chaozhou, Guangdong, People's Republic of China
| | - Jing-Li Wu
- 2014 Clinical Medicine Programme, Shantou University Medical College, Shantou, Guangdong, People's Republic of China
| | - Dan-Yan Xu
- 2014 Clinical Medicine Programme, Shantou University Medical College, Shantou, Guangdong, People's Republic of China
| | - Zhi-Mao Chen
- 2014 Clinical Medicine Programme, Shantou University Medical College, Shantou, Guangdong, People's Republic of China
| | - Yi-Long Cao
- 2014 Clinical Medicine Programme, Shantou University Medical College, Shantou, Guangdong, People's Republic of China
| | - Hai-Bin Chen
- Department of Histology and Embryology, Shantou University Medical College, Shantou, Guangdong, People's Republic of China.
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24
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Archer NM, Petersen N, Duraisingh MT. Fetal hemoglobin does not inhibit Plasmodium falciparum growth. Blood Adv 2019; 3:2149-2152. [PMID: 31311778 PMCID: PMC6650726 DOI: 10.1182/bloodadvances.2019000399] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 06/03/2019] [Indexed: 11/20/2022] Open
Abstract
P falciparum growth is not inhibited in either cord or heterozygote hereditary persistence of fetal hemoglobin erythrocytes. P falciparum growth in fetal hemoglobin erythrocytes is oxygen independent.
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Affiliation(s)
- Natasha M Archer
- Pediatric Hematology/Oncology, Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA; and
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Harvard University, Boston, MA
| | - Nicole Petersen
- Pediatric Hematology/Oncology, Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA; and
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Harvard University, Boston, MA
| | - Manoj T Duraisingh
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Harvard University, Boston, MA
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25
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Adamou R, Dechavanne C, Sadissou I, d'Almeida T, Bouraima A, Sonon P, Amoussa R, Cottrell G, Le Port A, Theisen M, Remarque EJ, Longacre S, Moutairou K, Massougbodji A, Luty AJF, Nuel G, Migot-Nabias F, Sanni A, Garcia A, Milet J, Courtin D. Plasmodium falciparum merozoite surface antigen-specific cytophilic IgG and control of malaria infection in a Beninese birth cohort. Malar J 2019; 18:194. [PMID: 31185998 PMCID: PMC6560827 DOI: 10.1186/s12936-019-2831-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 06/04/2019] [Indexed: 12/02/2022] Open
Abstract
Background Substantial evidence indicates that cytophilic IgG responses to Plasmodium falciparum merozoite antigens play a role in protection from malaria. The specific targets mediating immunity remain unclear. Evaluating antibody responses in infants naturally-exposed to malaria will allow to better understand the establishment of anti-malarial immunity and to contribute to a vaccine development by identifying the most appropriate merozoite candidate antigens. Methods The study was based on parasitological and clinical active follow-up of infants from birth to 18 months of age conducted in the Tori Bossito area of southern Benin. For 399 infants, plasma levels of cytophilic IgG antibodies with specificity for five asexual stage malaria vaccine candidate antigens were determined by ELISA in infants’ peripheral blood at 6, 9, 12 and 15 months of age. Multivariate mixed logistic model was used to investigate the association between antibody levels and anti-malarial protection in the trimester following the IgG quantification. Moreover, the concentrations of merozoite antigen-specific IgG were compared between a group of infants apparently able to control asymptomatic malaria infection (CAIG) and a group of infants with no control of malaria infection (Control group (NCIG)). Protective effect of antibodies was also assessed after 15 months of malaria exposure with a Cox regression model adjusted on environmental risk. Results Cytophilic IgG responses to AMA1, MSP1, MSP2-3D7, MSP2-FC27, MSP3 and GLURP R2 were associated with increasing malarial infection risk in univariate analysis. The multivariate mixed model showed that IgG1 and IgG3 to AMA1 were associated with an increased risk of malarial infection. However infants from CAIG (n = 53) had significantly higher AMA1-, MSP2-FC27-, MSP3-specific IgG1 and AMA1-, MSP1-, MSP2-FC27-, MSP3 and GLURP-R2-specific IgG3 than those from NCIG (n = 183). The latter IgG responses were not associated with protection against clinical malaria in the whole cohort when protective effect is assessed after 15 months of malaria exposition. Conclusion In this cohort, merozoite antigen-specific cytophilic IgG levels represent a marker of malaria exposure in infants from 6 to 18 months of age. However, infants with resolution of asymptomatic infection (CAIG) seem to have acquired naturally immunity against P. falciparum. This observation is encouraging in the context of the development of multitarget P. falciparum vaccines.
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Affiliation(s)
- Rafiou Adamou
- MERIT, IRD, Université de Paris, 75006, Paris, France. .,Centre d'Etude et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfance, Faculté des Sciences de la Santé, Université d'Abomey-Calavi, Cotonou, Benin. .,Laboratoire de Biochimie et de Biologie Moléculaire, Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Abomey Calavi, Benin.
| | | | - Ibrahim Sadissou
- MERIT, IRD, Université de Paris, 75006, Paris, France.,Centre d'Etude et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfance, Faculté des Sciences de la Santé, Université d'Abomey-Calavi, Cotonou, Benin.,Laboratoire de Biologie et Physiologie Cellulaires, Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Cotonou, Benin.,Division of Clinical Immunology, School of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil
| | | | - Aziz Bouraima
- Centre d'Etude et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfance, Faculté des Sciences de la Santé, Université d'Abomey-Calavi, Cotonou, Benin
| | - Paulin Sonon
- Centre d'Etude et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfance, Faculté des Sciences de la Santé, Université d'Abomey-Calavi, Cotonou, Benin.,Laboratoire de Biologie et Physiologie Cellulaires, Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Cotonou, Benin.,Division of Clinical Immunology, School of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil
| | - Roukiyath Amoussa
- Centre d'Etude et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfance, Faculté des Sciences de la Santé, Université d'Abomey-Calavi, Cotonou, Benin
| | | | - Agnès Le Port
- MERIT, IRD, Université de Paris, 75006, Paris, France
| | - Michael Theisen
- Department for Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark.,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
| | - Edmond J Remarque
- Department of Parasitology, Biomedical Primate Research Centre, Rijswijk, The Netherlands
| | - Shirley Longacre
- Laboratoire de Vaccinologie-Parasitaire, Institut Pasteur, Paris, France
| | - Kabirou Moutairou
- Laboratoire de Biologie et Physiologie Cellulaires, Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Cotonou, Benin
| | - Achille Massougbodji
- Centre d'Etude et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfance, Faculté des Sciences de la Santé, Université d'Abomey-Calavi, Cotonou, Benin
| | - Adrian J F Luty
- MERIT, IRD, Université de Paris, 75006, Paris, France.,Centre d'Etude et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfance, Faculté des Sciences de la Santé, Université d'Abomey-Calavi, Cotonou, Benin
| | - Gregory Nuel
- Laboratoire de Probabilités et Modèles aléatoires (LPMA), UMR CNRS 7599, UPMC, Paris, France
| | | | - Ambaliou Sanni
- Laboratoire de Biochimie et de Biologie Moléculaire, Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Abomey Calavi, Benin
| | - André Garcia
- MERIT, IRD, Université de Paris, 75006, Paris, France.,Centre d'Etude et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfance, Faculté des Sciences de la Santé, Université d'Abomey-Calavi, Cotonou, Benin
| | | | - David Courtin
- MERIT, IRD, Université de Paris, 75006, Paris, France
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26
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Mensah-Brown HE, Aspeling-Jones H, Delimini RK, Asante KP, Amlabu E, Bah SY, Beeson JG, Wright GJ, Conway DJ, Awandare GA. Antibody Reactivity to Merozoite Antigens in Ghanaian Adults Correlates With Growth Inhibitory Activity Against Plasmodium falciparum in Culture. Open Forum Infect Dis 2019; 6:ofz254. [PMID: 31294045 PMCID: PMC6611546 DOI: 10.1093/ofid/ofz254] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Accepted: 05/24/2019] [Indexed: 01/22/2023] Open
Abstract
Background Plasmodium falciparum uses a repertoire of merozoite-stage proteins for invasion of erythrocytes. Antibodies against some of these proteins halt the replication cycle of the parasite by preventing erythrocyte invasion and are implicated as contributors to protective immunity against malaria. Methods We assayed antibody reactivity against a panel of 9 recombinant antigens based on erythrocyte-binding antigen (EBA) and reticulocyte-like homolog (Rh) proteins in plasma from children with malaria and healthy adults residing in 3 endemic areas in Ghana using enzyme-linked immunosorbent assay. Purified immunoglobulin (Ig)G from adult plasma samples was also tested for invasion inhibition against 7 different P falciparum culture lines, including clinical isolates. Results Antibodies against the antigens increased in an age-dependent manner in children. Breadth of reactivity to the different antigens was strongly associated with in vitro parasite growth inhibitory activity of IgG purified from the adults. The strongest predictors of breadth of antibody reactivity were age and transmission intensity, and a combination of reactivities to Rh2, Rh4, and Rh5 correlated strongly with invasion inhibition. Conclusions Growth inhibitory activity was significantly associated with breadth of antibody reactivity to merozoite antigens, encouraging the prospect of a multicomponent blood-stage vaccine.
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Affiliation(s)
- Henrietta E Mensah-Brown
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Legon, Accra, Ghana.,Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, Accra, Ghana
| | | | - Rupert K Delimini
- Department of Biomedical Sciences, University of Health and Allied Sciences, Ho, Ghana
| | | | - Emmanuel Amlabu
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Legon, Accra, Ghana.,Department of Biochemistry, Kogi State University, Anyigba, Nigeria
| | - Saikou Y Bah
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Legon, Accra, Ghana.,Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, Accra, Ghana
| | - James G Beeson
- The Burnet Institute for Medical Research and Public Health, Melbourne, Australia.,Department of Microbiology, Monash University, Clayton, Australia
| | - Gavin J Wright
- Pathogens and Microbes Programme, Wellcome Trust Sanger Institute, United Kingdom
| | - David J Conway
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Gordon A Awandare
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Legon, Accra, Ghana.,Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, Accra, Ghana
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27
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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.
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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
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28
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Abstract
Neutrophils are abundant in the circulation and are one of the immune system's first lines of defense against infection. There has been substantial work carried out investigating the role of neutrophils in malaria and it is clear that during infection neutrophils are activated and are capable of clearing malaria parasites by a number of mechanisms. This review focuses on neutrophil responses to human malarias, summarizing evidence which helps us understand where neutrophils are, what they are doing, how they interact with parasites as well as their potential role in vaccine mediated immunity. We also outline future research priorities for these, the most abundant of leukocytes.
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Affiliation(s)
- Elizabeth H Aitken
- Department of Medicine at Royal Melbourne Hospital, Peter Doherty Institute, University of Melbourne, Melbourne, VIC, Australia
| | - Agersew Alemu
- Department of Medicine at Royal Melbourne Hospital, Peter Doherty Institute, University of Melbourne, Melbourne, VIC, Australia
| | - Stephen J Rogerson
- Department of Medicine at Royal Melbourne Hospital, Peter Doherty Institute, University of Melbourne, Melbourne, VIC, Australia
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29
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Kapulu MC, Njuguna P, Hamaluba MM. Controlled Human Malaria Infection in Semi-Immune Kenyan Adults (CHMI-SIKA): a study protocol to investigate in vivo Plasmodium falciparum malaria parasite growth in the context of pre-existing immunity. Wellcome Open Res 2018; 3:155. [PMID: 31803847 PMCID: PMC6871356 DOI: 10.12688/wellcomeopenres.14909.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2018] [Indexed: 10/20/2023] Open
Abstract
Malaria remains a major public health burden despite approval for implementation of a partially effective pre-erythrocytic malaria vaccine. There is an urgent need to accelerate development of a more effective multi-stage vaccine. Adults in malaria endemic areas may have substantial immunity provided by responses to the blood stages of malaria parasites, but field trials conducted on several blood-stage vaccines have not shown high levels of efficacy. We will use controlled human malaria infection (CHMI) studies with malaria-exposed volunteers to identify correlations between immune responses and parasite growth rates in vivo. Immune responses more strongly associated with control of parasite growth should be prioritized to accelerate malaria vaccine development. We aim to recruit up to 200 healthy adult volunteers from areas of differing malaria transmission in Kenya, and after confirming their health status through clinical examination and routine haematology and biochemistry, we will comprehensively characterize immunity to malaria using >100 blood-stage antigens. We will administer 3,200 aseptic, purified, cryopreserved Plasmodium falciparum sporozoites (PfSPZ Challenge) by direct venous inoculation. Serial quantitative polymerase chain reaction to measure parasite growth rate in vivo will be undertaken. Clinical and laboratory monitoring will be undertaken to ensure volunteer safety. In addition, we will also explore the perceptions and experiences of volunteers and other stakeholders in participating in a malaria volunteer infection study. Serum, plasma, peripheral blood mononuclear cells and extracted DNA will be stored to allow a comprehensive assessment of adaptive and innate host immunity. We will use CHMI in semi-immune adult volunteers to relate parasite growth outcomes with antibody responses and other markers of host immunity. Registration: ClinicalTrials.gov identifier NCT02739763.
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Affiliation(s)
- Melissa C. Kapulu
- KEMRI-Wellcome Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University Oxford, Oxford, UK
| | | | | | - CHMI-SIKA Study Team
- KEMRI-Wellcome Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University Oxford, Oxford, UK
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30
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Population Pharmacokinetic Properties of Sulfadoxine and Pyrimethamine: a Pooled Analysis To Inform Optimal Dosing in African Children with Uncomplicated Malaria. Antimicrob Agents Chemother 2018; 62:AAC.01370-17. [PMID: 29463542 PMCID: PMC5923181 DOI: 10.1128/aac.01370-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 02/09/2018] [Indexed: 02/07/2023] Open
Abstract
Sulfadoxine-pyrimethamine with amodiaquine is recommended by the World Health Organization as seasonal malaria chemoprevention for children aged 3 to 59 months in the sub-Sahel regions of Africa. Suboptimal dosing in children may lead to treatment failure and increased resistance. Pooled individual patient data from four previously published trials on the pharmacokinetics of sulfadoxine and pyrimethamine in 415 pediatric and 386 adult patients were analyzed using nonlinear mixed-effects modeling to evaluate the current dosing regimen and, if needed, to propose an optimized dosing regimen for children under 5 years of age. The population pharmacokinetics of sulfadoxine and pyrimethamine were both best described by a one-compartment disposition model with first-order absorption and elimination. Body weight, age, and nutritional status (measured as the weight-for-age Z-score) were found to be significant covariates. Allometric scaling with total body weight and the maturation of clearance in children by postgestational age improved the model fit. Underweight-for-age children were found to have 15.3% and 26.7% lower bioavailabilities of sulfadoxine and pyrimethamine, respectively, for each Z-score unit below -2. Under current dosing recommendations, simulation predicted that the median day 7 concentration was below the 25th percentile for a typical adult patient (50 kg) for sulfadoxine for patients in the weight bands of 8 to 9, 19 to 24, 46 to 49, and 74 to 79 kg and for pyrimethamine for patients in the weight bands of 8 to 9, 14 to 24, and 42 to 49 kg. An evidence-based dosing regimen was constructed that would achieve sulfadoxine and pyrimethamine exposures in young children and underweight-for-age young children that were similar to those currently seen in a typical adult.
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31
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Barua P, Chandrasiri UP, Beeson JG, Dewey KG, Maleta K, Ashorn P, Rogerson SJ. Effect of nutrient supplementation on the acquisition of humoral immunity to Plasmodium falciparum in young Malawian children. Malar J 2018; 17:74. [PMID: 29415730 PMCID: PMC5804088 DOI: 10.1186/s12936-018-2224-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 01/31/2018] [Indexed: 11/17/2022] Open
Abstract
Background There is evidence that suggests that undernutrition has a detrimental effect on malarial immunity in children. The aim of the study was to discover whether nutrient supplementation improved development of malarial antibody immunity in children up to 18 months of age. Methods The study was conducted with a subset of 432 Malawian children from a randomized controlled trial of nutritional supplements. The arms included pre- and postnatal small-quantity lipid-based nutrient supplements for both mother and child; prenatal supplementation with iron and folic acid; and pre- and postnatal supplementation with multiple micronutrients. Paired plasma samples were collected at 6 and 18 months of age. The levels of antibodies against merozoite surface protein 1 (MSP1 19kD) and MSP2, erythrocyte binding antigen 175 (EBA175), reticulocyte binding protein homologue 2A (Rh2A9), schizont extract and variant antigens expressed on the surface of infected erythrocytes were measured. Results At 18 months of age, 5.4% of children were parasitaemic by microscopy and 49.1% were anaemic. Antibodies to the tested merozoite antigens and schizont extract increased between 6 and 18 months and this increase was statistically significant for MSP1, MSP2 and EBA175 (p < 0.0001) whereas IgG to variant surface antigens decreased with increasing age (p < 0.0001). However, the supplementation type did not have any impact on the prevalence or levels of antibodies at either 6 or 18 months of age to any of the tested malaria antigens in either univariate analysis or multivariate analysis after adjusting for covariates. Conclusions Pre- and postnatal lipid-based nutrient supplementation did not alter malaria antibody acquisition during infancy, compared to prenatal supplementation with iron and folic acid or pre- and postnatal supplementation with multiple micronutrients. Trail registeration Clinicaltrials.gov registration number NCT01239693
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Affiliation(s)
- Priyanka Barua
- Department of Medicine (RMH), Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia
| | - Upeksha P Chandrasiri
- Department of Medicine (RMH), Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia
| | - James G Beeson
- Department of Medicine (RMH), Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia.,Burnet Institute for Medical Research and Public Health, Melbourne, VIC, Australia.,Monash University, Melbourne, VIC, Australia
| | | | | | - Per Ashorn
- University of Tampere and Tampere University Hospital, Tampere, Finland
| | - Stephen J Rogerson
- Department of Medicine (RMH), Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia.
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32
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Mechanisms of naturally acquired immunity to P. falciparum and approaches to identify merozoite antigen targets. Parasitology 2017; 145:839-847. [PMID: 29144217 DOI: 10.1017/s0031182017001949] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Malaria is one the most serious infectious diseases with over 200 million clinical cases annually. Most cases of the severe disease are caused by Plasmodium falciparum. The blood stage of Plasmodium parasite is entirely responsible for malaria-associated pathology. The population most susceptible to severe malaria are children under the age of 5, with low levels of immunity. It is only after many years of repeated exposure that individuals living in endemic areas develop clinical immunity. This form of protection prevents clinical episodes by substantially reducing parasite burden. Naturally acquired immunity predominantly targets blood-stage parasites with antibody responses being the main mediators of protection. The targets of clinical immunity are the extracellular merozoite and the infected erythrocyte surface, with the extremely diverse PfEMP1 proteins the main target here. This observation provides a strong rationale that an effective anti-malaria vaccine targeting blood-stage parasites is achievable. Thus the identification of antigenic targets of naturally acquired immunity remains an important step towards the formulation of novel vaccine combinations before testing their efficacy in clinical trials. This review summarizes the main findings to date defining antigenic targets present on the extracellular merozoite associated with naturally acquired immunity to P. falciparum malaria.
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33
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Merozoite Surface Protein 1 from Plasmodium falciparum Is a Major Target of Opsonizing Antibodies in Individuals with Acquired Immunity against Malaria. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2017; 24:CVI.00155-17. [PMID: 28877929 DOI: 10.1128/cvi.00155-17] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 08/31/2017] [Indexed: 11/20/2022]
Abstract
Naturally acquired immunity against malaria is largely mediated by serum antibodies controlling levels of blood-stage parasites. A limited understanding of the antigenic targets and functional mechanisms of protective antibodies has hampered the development of efficient malaria vaccines. Besides directly inhibiting the growth of Plasmodium parasites, antibodies can opsonize merozoites and recruit immune effector cells such as monocytes and neutrophils. Antibodies against the vaccine candidate merozoite surface protein 1 (MSP-1) are acquired during natural infections and have been associated with protection against malaria in several epidemiological studies. Here we analyzed serum antibodies from semi-immune individuals from Burkina Faso for their potential (i) to directly inhibit the growth of P. falciparum blood stages in vitro and (ii) to opsonize merozoites and to induce the antibody-dependent respiratory burst (ADRB) activity of neutrophils. While a few sera that directly inhibited the growth of P. falciparum blood stages were identified, immunoglobulin G (IgG) from all individuals clearly mediated the activation of neutrophils. The level of neutrophil activation correlated with levels of antibodies to MSP-1, and affinity-purified MSP-1-specific antibodies elicited ADRB activity. Furthermore, immunization of nonhuman primates with recombinant full-size MSP-1 induced antibodies that efficiently opsonized P. falciparum merozoites. Reversing the function by preincubation with recombinant antigens allowed us to quantify the contribution of MSP-1 to the antiparasitic effect of serum antibodies. Our data suggest that MSP-1, especially the partially conserved subunit MSP-183, is a major target of opsonizing antibodies acquired during natural exposure to malaria. Induction of opsonizing antibodies might be a crucial effector mechanism for MSP-1-based malaria vaccines.
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34
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Perraut R, Varela ML, Joos C, Diouf B, Sokhna C, Mbengue B, Tall A, Loucoubar C, Touré A, Mercereau-Puijalon O. Association of antibodies to Plasmodium falciparum merozoite surface protein-4 with protection against clinical malaria. Vaccine 2017; 35:6720-6726. [PMID: 29042203 DOI: 10.1016/j.vaccine.2017.10.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Revised: 09/10/2017] [Accepted: 10/05/2017] [Indexed: 11/17/2022]
Abstract
Identification of parasite antigens targeted by immune effector mechanisms that confer protection against malaria is important for the design of a multi-component malaria vaccine. Here, the association of antibodies reacting with the Plasmodium falciparum merozoite surface protein-4 (MSP4) with protection against clinical malaria was investigated in a Senegalese community living in an area of moderate, seasonal malaria transmission. Blood samples were collected at the end of an 8-month long dry season without any recorded parasite transmission from 206 residents enrolled in a prospective follow-up study. Active daily clinical monitoring was implemented during the subsequent five months. Entomologic monitoring documented parasite transmission during the first three months of follow-up. Serum IgG levels were determined by ELISA against three MSP4 baculovirus-encoded recombinant protein constructs, namely the full-length MSP4p40, MSP4p30 devoid of a highly polymorphic sequence stretch and the conserved C-terminal EGF-containing MSP4p20, as well as against a merozoite crude extract. Community seroprevalence against all three constructs was quite high, the lowest being against MSP4p30. Seroprevalence and antibody levels against the three MSP4 constructs were age-dependent. IgG1 dominated the anti-MSP4p20 responses, while both IgG1 and IgG3 were observed against MSP4p40. Anti-MSP4 antibodies were associated with the antibody-dependent respiratory burst (ADRB) activity in a functional assay of merozoite phagocytosis by polymorphonuclear cells. Importantly, high antibody levels against each of the three MSP4 constructs at the end of the dry season were associated with reduced morbidity during the subsequent transmission season in an age-adjusted Poisson regression model (IRR = 0.65 [0.50-0.83], P<0.001 for responses over the median values). These data are consistent with a protective role for the naturally acquired anti-MSP4 antibodies and support further development of MSP4 as a candidate component of malaria vaccine.
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Affiliation(s)
- Ronald Perraut
- Unité d'Immunologie, Institut Pasteur de Dakar, Senegal.
| | | | | | - Babacar Diouf
- Unité d'Immunologie, Institut Pasteur de Dakar, Senegal
| | - Cheikh Sokhna
- Institut de Recherche pour le Développement (IRD), URMITE, UMR 198, Dakar, Senegal
| | | | - Adama Tall
- Unité d'Epidémiologie, Institut Pasteur de Dakar, Senegal
| | - Cheikh Loucoubar
- Institut Pasteur de Dakar, G4 Biostatistiques Bioinformatique et Modélisation, Dakar, Senegal
| | | | - Odile Mercereau-Puijalon
- Institut Pasteur, Département Parasites et Insectes Vecteurs, 25 Rue du Dr. Roux, 75015 Paris, France
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35
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Tuju J, Kamuyu G, Murungi LM, Osier FHA. Vaccine candidate discovery for the next generation of malaria vaccines. Immunology 2017; 152:195-206. [PMID: 28646586 PMCID: PMC5588761 DOI: 10.1111/imm.12780] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 06/12/2017] [Accepted: 06/19/2017] [Indexed: 12/21/2022] Open
Abstract
Although epidemiological observations, IgG passive transfer studies and experimental infections in humans all support the feasibility of developing highly effective malaria vaccines, the precise antigens that induce protective immunity remain uncertain. Here, we review the methodologies applied to vaccine candidate discovery for Plasmodium falciparum malaria from the pre- to post-genomic era. Probing of genomic and cDNA libraries with antibodies of defined specificities or functional activity predominated the former, whereas reverse vaccinology encompassing high throughput in silico analyses of genomic, transcriptomic or proteomic parasite data sets is the mainstay of the latter. Antibody-guided vaccine design spanned both eras but currently benefits from technological advances facilitating high-throughput screening and downstream applications. We make the case that although we have exponentially increased our ability to identify numerous potential vaccine candidates in a relatively short space of time, a significant bottleneck remains in their validation and prioritization for evaluation in clinical trials. Longitudinal cohort studies provide supportive evidence but results are often conflicting between studies. Demonstration of antigen-specific antibody function is valuable but the relative importance of one mechanism over another with regards to protection remains undetermined. Animal models offer useful insights but may not accurately reflect human disease. Challenge studies in humans are preferable but prohibitively expensive. In the absence of reliable correlates of protection, suitable animal models or a better understanding of the mechanisms underlying protective immunity in humans, vaccine candidate discovery per se may not be sufficient to provide the paradigm shift necessary to develop the next generation of highly effective subunit malaria vaccines.
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Affiliation(s)
- James Tuju
- KEMRI‐Wellcome Trust Research ProgrammeCentre for Geographic Medicine CoastKilifiKenya
- Department of BiochemistryPwani UniversityKilifiKenya
| | - Gathoni Kamuyu
- KEMRI‐Wellcome Trust Research ProgrammeCentre for Geographic Medicine CoastKilifiKenya
| | - Linda M. Murungi
- KEMRI‐Wellcome Trust Research ProgrammeCentre for Geographic Medicine CoastKilifiKenya
| | - Faith H. A. Osier
- KEMRI‐Wellcome Trust Research ProgrammeCentre for Geographic Medicine CoastKilifiKenya
- Centre for Infectious DiseasesHeidelberg University HospitalHeidelbergGermany
- Department of Biomedical SciencesPwani UniversityKilifiKenya
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36
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França CT, White MT, He WQ, Hostetler JB, Brewster J, Frato G, Malhotra I, Gruszczyk J, Huon C, Lin E, Kiniboro B, Yadava A, Siba P, Galinski MR, Healer J, Chitnis C, Cowman AF, Takashima E, Tsuboi T, Tham WH, Fairhurst RM, Rayner JC, King CL, Mueller I. Identification of highly-protective combinations of Plasmodium vivax recombinant proteins for vaccine development. eLife 2017; 6:28673. [PMID: 28949293 PMCID: PMC5655538 DOI: 10.7554/elife.28673] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 09/25/2017] [Indexed: 12/22/2022] Open
Abstract
The study of antigenic targets of naturally-acquired immunity is essential to identify and prioritize antigens for further functional characterization. We measured total IgG antibodies to 38 P. vivax antigens, investigating their relationship with prospective risk of malaria in a cohort of 1–3 years old Papua New Guinean children. Using simulated annealing algorithms, the potential protective efficacy of antibodies to multiple antigen-combinations, and the antibody thresholds associated with protection were investigated for the first time. High antibody levels to multiple known and newly identified proteins were strongly associated with protection (IRR 0.44–0.74, p<0.001–0.041). Among five-antigen combinations with the strongest protective effect (>90%), EBP, DBPII, RBP1a, CyRPA, and PVX_081550 were most frequently identified; several of them requiring very low antibody levels to show a protective association. These data identify individual antigens that should be prioritized for further functional testing and establish a clear path to testing a multicomponent P. vivax vaccine.
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Affiliation(s)
- Camila Tenorio França
- Division of Population Health and Immunity, Walter and Eliza Hall Institute, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Australia
| | - Michael T White
- Division of Population Health and Immunity, Walter and Eliza Hall Institute, Parkville, Australia.,MRC Center for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Wen-Qiang He
- Department of Medical Biology, University of Melbourne, Parkville, Australia.,Division of Infection and Immunity, Walter and Eliza Hall Institute, Parkville, Australia
| | - Jessica B Hostetler
- Malaria Programme, Wellcome Trust Sanger Institute, Hinxton, United Kingdom.,Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, United States
| | - Jessica Brewster
- Division of Infection and Immunity, Walter and Eliza Hall Institute, Parkville, Australia
| | - Gabriel Frato
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, United States
| | - Indu Malhotra
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, United States
| | - Jakub Gruszczyk
- Division of Infection and Immunity, Walter and Eliza Hall Institute, Parkville, Australia
| | - Christele Huon
- Malaria Parasite Biology and Vaccines Unit, Institut Pasteur, Paris, France
| | - Enmoore Lin
- Malaria Immuno-Epidemiology Unit, PNG Institute of Medical Research, Yagaum, Papua New Guinea
| | - Benson Kiniboro
- Malaria Immuno-Epidemiology Unit, PNG Institute of Medical Research, Yagaum, Papua New Guinea
| | - Anjali Yadava
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, United States
| | - Peter Siba
- Malaria Immuno-Epidemiology Unit, PNG Institute of Medical Research, Yagaum, Papua New Guinea
| | - Mary R Galinski
- International Center for Malaria Research, Education, and Development, Emory Vaccine Center, Yerkes National Primate Research Center, Emory University, Atlanta, United States.,Infectious Diseases Division, Department of Medicine, Emory University, Atlanta, United States
| | - Julie Healer
- Department of Medical Biology, University of Melbourne, Parkville, Australia.,Division of Infection and Immunity, Walter and Eliza Hall Institute, Parkville, Australia
| | - Chetan Chitnis
- Malaria Parasite Biology and Vaccines Unit, Institut Pasteur, Paris, France.,International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Alan F Cowman
- Department of Medical Biology, University of Melbourne, Parkville, Australia.,Division of Infection and Immunity, Walter and Eliza Hall Institute, Parkville, Australia
| | - Eizo Takashima
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, United States
| | - Takafumi Tsuboi
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - Wai-Hong Tham
- Department of Medical Biology, University of Melbourne, Parkville, Australia.,Division of Infection and Immunity, Walter and Eliza Hall Institute, Parkville, Australia
| | - Rick M Fairhurst
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, United States
| | - Julian C Rayner
- Malaria Programme, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - Christopher L King
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, United States
| | - Ivo Mueller
- Division of Population Health and Immunity, Walter and Eliza Hall Institute, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Australia.,Malaria Parasites and Hosts Unit, Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France.,Barcelona Institute of Global Health, Barcelona, Spain
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Fang R, Wey A, Bobbili NK, Leke RFG, Taylor DW, Chen JJ. An analytical approach to reduce between-plate variation in multiplex assays that measure antibodies to Plasmodium falciparum antigens. Malar J 2017; 16:287. [PMID: 28716094 PMCID: PMC5513105 DOI: 10.1186/s12936-017-1933-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 07/11/2017] [Indexed: 11/29/2022] Open
Abstract
Background Antibodies play an important role in immunity to malaria. Recent studies show that antibodies to multiple antigens, as well as, the overall breadth of the response are associated with protection from malaria. Yet, the variability and reliability of antibody measurements against a combination of malarial antigens using multiplex assays have not been well characterized. Methods A normalization procedure for reducing between-plate variation using replicates of pooled positive and negative controls was investigated. Sixty test samples (30 from malaria-positive and 30 malaria-negative individuals), together with five pooled positive-controls and two pooled negative-controls, were screened for antibody levels to 9 malarial antigens, including merozoite antigens (AMA1, EBA175, MSP1, MSP2, MSP3, MSP11, Pf41), sporozoite CSP, and pregnancy-associated VAR2CSA. The antibody levels were measured in triplicate on each of 3 plates, and the experiments were replicated on two different days by the same technician. The performance of the proposed normalization procedure was evaluated with the pooled controls for the test samples on both the linear and natural-log scales. Results Compared with data on the linear scale, the natural-log transformed data were less skewed and reduced the mean–variance relationship. The proposed normalization procedure using pooled controls on the natural-log scale significantly reduced between-plate variation. Conclusions For malaria-related research that measure antibodies to multiple antigens with multiplex assays, the natural-log transformation is recommended for data analysis and use of the normalization procedure with multiple pooled controls can improve the precision of antibody measurements. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-1933-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rui Fang
- Office of Biostatistics and Quantitative Health Sciences, University of Hawaii John A. Burns School of Medicine, Honolulu, HI, 96813, USA
| | - Andrew Wey
- Office of Biostatistics and Quantitative Health Sciences, University of Hawaii John A. Burns School of Medicine, Honolulu, HI, 96813, USA
| | - Naveen K Bobbili
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, University of Hawaii John A. Burns School of Medicine, 651 Ilalo Street, BSB 211, Honolulu, HI, 96813, USA
| | - Rose F G Leke
- Biotechnology Center, Faculty of Medicine and Biomedical Research, University of Yaounde 1, Yaounde, Cameroon
| | - Diane Wallace Taylor
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, University of Hawaii John A. Burns School of Medicine, 651 Ilalo Street, BSB 211, Honolulu, HI, 96813, USA
| | - John J Chen
- Office of Biostatistics and Quantitative Health Sciences, University of Hawaii John A. Burns School of Medicine, Honolulu, HI, 96813, USA.
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38
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Hill DL, Schofield L, Wilson DW. IgG opsonization of merozoites: multiple immune mechanisms for malaria vaccine development. Int J Parasitol 2017; 47:585-595. [PMID: 28668325 DOI: 10.1016/j.ijpara.2017.05.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 04/12/2017] [Accepted: 05/12/2017] [Indexed: 02/07/2023]
Abstract
Global eradication of the human-infecting malaria parasite Plasmodium falciparum, the major cause of malaria mortality, is unlikely to be achieved without an effective vaccine. However, our limited understanding of how protective immune responses target malaria parasites in humans, and how to best elicit these immune responses through vaccination, has hampered vaccine development. The red blood cell invading stage of the parasite lifecycle (merozoite) displays antigens that are attractive vaccine candidates as they are accessible to antibodies and raise high antibody titres in naturally immune individuals. The number of merozoite antigens that elicit an immune response, and their structural and functional diversity, has led to a large number of lead antigens being pursued as vaccine candidates. Despite being seemingly spoilt for choice in terms of vaccine candidates, there is still a lack of consensus on exactly how merozoite antibodies reduce parasitemia and malaria disease. In this review we describe the various immune mechanisms that can result from IgG opsonization of merozoites, and highlight recent developments that support a role for these functional antibodies in naturally acquired and vaccine-induced immunity.
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Affiliation(s)
- Danika L Hill
- Babraham Institute, Babraham Research Campus, Cambridge, United Kingdom; The Walter and Eliza Hall Institute of Medical Research, Parkville, Australia; Department of Medical Biology, University of Melbourne, Parkville, Australia.
| | - Louis Schofield
- Australian Institute of Tropical Health and Medicine, James Cook University, Townsville, Australia
| | - Danny W Wilson
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, Australia; Burnet Institute, 85 Commercial Road, Melbourne 3004, Victoria, Australia.
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39
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A Plasmodium vivax Plasmid DNA- and Adenovirus-Vectored Malaria Vaccine Encoding Blood-Stage Antigens AMA1 and MSP1 42 in a Prime/Boost Heterologous Immunization Regimen Partially Protects Aotus Monkeys against Blood-Stage Challenge. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2017; 24:CVI.00539-16. [PMID: 28179404 DOI: 10.1128/cvi.00539-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 02/06/2017] [Indexed: 01/30/2023]
Abstract
Malaria is caused by parasites of the genus Plasmodium, which are transmitted to humans by the bites of Anopheles mosquitoes. After the elimination of Plasmodium falciparum, it is predicted that Plasmodium vivax will remain an important cause of morbidity and mortality outside Africa, stressing the importance of developing a vaccine against P. vivax malaria. In this study, we assessed the immunogenicity and protective efficacy of two P. vivax antigens, apical membrane antigen 1 (AMA1) and the 42-kDa C-terminal fragment of merozoite surface protein 1 (MSP142) in a plasmid recombinant DNA prime/adenoviral (Ad) vector boost regimen in Aotus monkeys. Groups of 4 to 5 monkeys were immunized with plasmid DNA alone, Ad alone, prime/boost regimens with each antigen, prime/boost regimens with both antigens, and empty vector controls and then subjected to blood-stage challenge. The heterologous immunization regimen with the antigen pair was more protective than either antigen alone or both antigens delivered with a single vaccine platform, on the basis of their ability to induce the longest prepatent period and the longest time to the peak level of parasitemia, the lowest peak and mean levels of parasitemia, the smallest area under the parasitemia curve, and the highest self-cure rate. Overall, prechallenge MSP142 antibody titers strongly correlated with a decreased parasite burden. Nevertheless, a significant proportion of immunized animals developed anemia. In conclusion, the P. vivax plasmid DNA/Ad serotype 5 vaccine encoding blood-stage parasite antigens AMA1 and MSP142 in a heterologous prime/boost immunization regimen provided significant protection against blood-stage challenge in Aotus monkeys, indicating the suitability of these antigens and this regimen for further development.
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40
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T cell subtypes and reciprocal inflammatory mediator expression differentiate P. falciparum memory recall responses in asymptomatic and symptomatic malaria patients in southeastern Haiti. PLoS One 2017; 12:e0174718. [PMID: 28369062 PMCID: PMC5378365 DOI: 10.1371/journal.pone.0174718] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 03/14/2017] [Indexed: 12/20/2022] Open
Abstract
Asymptomatic Plasmodium falciparum infection is responsible for maintaining malarial disease within human populations in low transmission countries such as Haiti. Investigating differential host immune responses to the parasite as a potential underlying mechanism could help provide insight into this highly complex phenomenon and possibly identify asymptomatic individuals. We performed a cross-sectional analysis of individuals who were diagnosed with malaria in Sud-Est, Haiti by comparing the cellular and humoral responses of both symptomatic and asymptomatic subjects. Plasma samples were analyzed with a P. falciparum protein microarray, which demonstrated serologic reactivity to 3,877 P. falciparum proteins of known serologic reactivity; however, no antigen-antibody reactions delineating asymptomatics from symptomatics were identified. In contrast, differences in cellular responses were observed. Flow cytometric analysis of patient peripheral blood mononuclear cells co-cultured with P. falciparum infected erythrocytes demonstrated a statistically significant increase in the proportion of T regulatory cells (CD4+ CD25+ CD127-), and increases in unique populations of both NKT-like cells (CD3+ CD8+ CD56+) and CD8mid T cells in asymptomatics compared to symptomatics. Also, CD38+/HLA-DR+ expression on γδ T cells, CD8mid (CD56-) T cells, and CD8mid CD56+ NKT-like cells decreased upon exposure to infected erythrocytes in both groups. Cytometric bead analysis of the co-culture supernatants demonstrated an upregulation of monocyte-activating chemokines/cytokines in asymptomatics, while immunomodulatory soluble factors were elevated in symptomatics. Principal component analysis of these expression values revealed a distinct clustering of individual responses within their respective phenotypic groups. This is the first comprehensive investigation of immune responses to P. falciparum in Haiti, and describes unique cell-mediated immune repertoires that delineate individuals into asymptomatic and symptomatic phenotypes. Future investigations using large scale biological data sets analyzing multiple components of adaptive immunity, could collectively define which cellular responses and molecular correlates of disease outcome are malaria region specific, and which are truly generalizable features of asymptomatic Plasmodium immunity, a research goal of critical priority.
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41
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Rogier E, Moss DM, Chard AN, Trinies V, Doumbia S, Freeman MC, Lammie PJ. Evaluation of Immunoglobulin G Responses to Plasmodium falciparum and Plasmodium vivax in Malian School Children Using Multiplex Bead Assay. Am J Trop Med Hyg 2016; 96:312-318. [PMID: 27895279 DOI: 10.4269/ajtmh.16-0476] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 10/21/2016] [Indexed: 12/23/2022] Open
Abstract
Malaria serology through assaying for IgG against Plasmodium spp. antigens provides evidence into the infection history for an individual. The multiplex bead assay (MBA) allows for detection of IgG against multiple Plasmodium spp., and can be especially useful in many regions where Plasmodium falciparum is of primary clinical focus, but other species are co-endemic. Dried blood spots were collected from 805 Malian children attending 42 elementary schools in the regions of Mopti, Sikasso, Koulikoro, and Bamako capital district, and IgG assayed by MBA. As southern Mali is known to be holoendemic for P. falciparum, merozoite surface protein 1 19-kDa subunit (MSP-142) and apical membrane antigen 1 (AMA-1) antigens were included for serology against this parasite. Responses to these antigens both provided high estimates for lifetime exposure, with 730 (90%) children with IgG antibodies for MSP-142, 737 (91%) for AMA-1, and 773 (96%) positive for either or both. Also included was the antigen Plasmodium vivax MSP-119, against which 140 (17.4%) children were found to have antibodies. Increases in antibody titers with older age were clearly seen with the P. falciparum antigens, but not with the P. vivax antigen, likely indicating more of a sporadic, rather than sustained transmission for this species. The MBA provides effective opportunities to evaluate malaria transmission through serological analysis for multiple Plasmodium species.
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Affiliation(s)
- Eric Rogier
- Division of Parasitic Diseases and Malaria, Centers for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia.
| | - Delynn M Moss
- Division of Foodborne, Waterborne, and Environmental Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Anna N Chard
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia
| | - Victoria Trinies
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia
| | - Seydou Doumbia
- Malaria Research and Training Center, Faculty of Medicine and Odontostomatology, University of Sciences, Techniques and Technologies of Bamako (USTTB), Bamako, Mali
| | - Matthew C Freeman
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia
| | - Patrick J Lammie
- Division of Parasitic Diseases and Malaria, Centers for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia
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42
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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.
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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
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Hodgson SH, Llewellyn D, Silk SE, Milne KH, Elias SC, Miura K, Kamuyu G, Juma EA, Magiri C, Muia A, Jin J, Spencer AJ, Longley RJ, Mercier T, Decosterd L, Long CA, Osier FH, Hoffman SL, Ogutu B, Hill AVS, Marsh K, Draper SJ. Changes in Serological Immunology Measures in UK and Kenyan Adults Post-controlled Human Malaria Infection. Front Microbiol 2016; 7:1604. [PMID: 27790201 PMCID: PMC5061779 DOI: 10.3389/fmicb.2016.01604] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 09/26/2016] [Indexed: 11/15/2022] Open
Abstract
Background: The timing of infection is closely determined in controlled human malaria infection (CHMI) studies, and as such they provide a unique opportunity to dissect changes in immunological responses before and after a single infection. The first Kenyan Challenge Study (KCS) (Pan African Clinical Trial Registry: PACTR20121100033272) was performed in 2013 with the aim of establishing the CHMI model in Kenya. This study used aseptic, cryopreserved, attenuated Plasmodium falciparum sporozoites administered by needle and syringe (PfSPZ Challenge) and was the first to evaluate parasite dynamics post-CHMI in individuals with varying degrees of prior exposure to malaria. Methods: We describe detailed serological and functional immunological responses pre- and post-CHMI for participants in the KCS and compare these with those from malaria-naïve UK volunteers who also underwent CHMI (VAC049) (ClinicalTrials.gov NCT01465048) using PfSPZ Challenge. We assessed antibody responses to three key blood-stage merozoite antigens [merozoite surface protein 1 (MSP1), apical membrane protein 1 (AMA1), and reticulocyte-binding protein homolog 5 (RH5)] and functional activity using two candidate measures of anti-merozoite immunity; the growth inhibition activity (GIA) assay and the antibody-dependent respiratory burst activity (ADRB) assay. Results:Clear serological differences were observed pre- and post-CHMI by ELISA between malaria-naïve UK volunteers in VAC049, and Kenyan volunteers who had prior malaria exposure. Antibodies to AMA1 and schizont extract correlated with parasite multiplication rate (PMR) post-CHMI in KCS. Serum from volunteer 110 in KCS, who demonstrated a dramatically reduced PMR in vivo, had no in vitro GIA prior to CHMI but the highest level of ADRB activity. A significant difference in ADRB activity was seen between KCS volunteers with minimal and definite prior exposure to malaria and significant increases were seen in ADRB activity post-CHMI in Kenyan volunteers. Quinine and atovaquone/proguanil, previously assumed to be removed by IgG purification, were identified as likely giving rise to aberrantly high in vitro GIA results. Conclusions: The ADRB activity assay is a promising functional assay that warrants further investigation as a measure of prior exposure to malaria and predictor of control of parasite growth. The CHMI model can be used to evaluate potential measures of naturally-acquired immunity to malaria.
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Affiliation(s)
| | | | - Sarah E Silk
- The Jenner Institute, University of Oxford Oxford, UK
| | | | - Sean C Elias
- The Jenner Institute, University of Oxford Oxford, UK
| | - Kazutoyo Miura
- Laboratory of Malaria and Vector Research, NIH-National Institute of Allergy and Infectious Diseases Rockville, MD, USA
| | - Gathoni Kamuyu
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute-Wellcome Trust Kilifi, Kenya
| | - Elizabeth A Juma
- Centre for Clinical Research, Kenya Medical Research InstituteNairobi, Kenya; Centre for Research in Therapeutic Sciences, Strathmore UniversityNairobi, Kenya
| | - Charles Magiri
- Centre for Clinical Research, Kenya Medical Research Institute Nairobi, Kenya
| | - Alfred Muia
- Centre for Clinical Research, Kenya Medical Research Institute Nairobi, Kenya
| | - Jing Jin
- The Jenner Institute, University of Oxford Oxford, UK
| | | | | | - Thomas Mercier
- Division of Clinical Pharmacology, Hôpital Beaumont, Université de Lausanne Lausanne, Switzerland
| | - Laurent Decosterd
- Division of Clinical Pharmacology, Hôpital Beaumont, Université de Lausanne Lausanne, Switzerland
| | - Carole A Long
- Laboratory of Malaria and Vector Research, NIH-National Institute of Allergy and Infectious Diseases Rockville, MD, USA
| | - Faith H Osier
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute-Wellcome Trust Kilifi, Kenya
| | | | - Bernhards Ogutu
- Centre for Clinical Research, Kenya Medical Research InstituteNairobi, Kenya; Centre for Research in Therapeutic Sciences, Strathmore UniversityNairobi, Kenya
| | | | - Kevin Marsh
- Centre for Geographical Medical Research (Coast), Kenya Medical Research Institute-Wellcome TrustKilifi, Kenya; Department of Tropical Medicine, University of OxfordOxford, UK
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Teo A, Feng G, Brown GV, Beeson JG, Rogerson SJ. Functional Antibodies and Protection against Blood-stage Malaria. Trends Parasitol 2016; 32:887-898. [PMID: 27546781 DOI: 10.1016/j.pt.2016.07.003] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 07/09/2016] [Accepted: 07/14/2016] [Indexed: 01/06/2023]
Abstract
Numerous efforts to understand the functional roles of antibodies demonstrated that they can protect against malaria. However, it is unclear which antibody responses are the best correlates of immunity, and which antibody functions are most important in protection from disease. Understanding the role of antibodies in protection against malaria is crucial for antimalarial vaccine design. In this review, the specific functional properties of naturally acquired and vaccine-induced antibodies that correlate to protection from the blood stages of Plasmodium falciparum malaria are re-examined and the gaps in knowledge related to antibody function in malarial immunity are highlighted.
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Affiliation(s)
- Andrew Teo
- Department of Medicine, University of Melbourne (Royal Melbourne Hospital), Parkville, Australia; Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Australia
| | - Gaoqian Feng
- Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Australia
| | - Graham V Brown
- Department of Medicine, University of Melbourne (Royal Melbourne Hospital), Parkville, Australia; Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Australia; Victorian Infectious Diseases Service, Doherty Institute for Infection and Immunity, Melbourne, Australia
| | - James G Beeson
- Department of Medicine, University of Melbourne (Royal Melbourne Hospital), Parkville, Australia; Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Australia; Department of Microbiology, Monash University, Melbourne, Victoria, Australia
| | - Stephen J Rogerson
- Department of Medicine, University of Melbourne (Royal Melbourne Hospital), Parkville, Australia; Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Australia; Victorian Infectious Diseases Service, Doherty Institute for Infection and Immunity, Melbourne, Australia.
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