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Prah DA, Laryea-Akrong E. Asymptomatic Low-Density Plasmodium falciparum Infections: Parasites Under the Host's Immune Radar? J Infect Dis 2024; 229:1913-1918. [PMID: 38349649 PMCID: PMC11175676 DOI: 10.1093/infdis/jiad581] [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: 09/25/2023] [Accepted: 12/18/2023] [Indexed: 06/15/2024] Open
Abstract
A large body of evidence suggests that low parasite carriage in Plasmodium falciparum asymptomatic infection is required for the maintenance of malaria immunity. However, the fact that treating such infections has little to no impact on subsequent clinical malaria is rarely noted. In this paper, we review data and argue that low-density parasite carriage in asymptomatic infection may not support host immune processes and that parasites are virtually under the host's immunological radar. We also discuss factors that may be constraining parasitemia in asymptomatic infections from reaching the threshold required to cause clinical symptoms. A thorough understanding of this infectious reservoir is essential for malaria control and eradication because asymptomatic infections contribute significantly to Plasmodium transmission.
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Affiliation(s)
- Diana Ahu Prah
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Legon, Ghana
- Faculty of Applied Sciences, Department of Science Laboratory Technology, Accra Technical University, Accra, Ghana
| | - Elizabeth Laryea-Akrong
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Legon, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
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Baina MT, Lissom A, Assioro Doulamo NV, Djontu JC, Umuhoza DM, Mbama-Ntabi JD, Diafouka-Kietela S, Mayela J, Missontsa G, Wondji C, Adegnika AA, Nguimbi E, Borrmann S, Ntoumi F. Comparative study of Plasmodium falciparum msp-1 and msp-2 Genetic Diversity in Isolates from Rural and Urban Areas in the South of Brazzaville, Republic of Congo. Pathogens 2023; 12:pathogens12050742. [PMID: 37242412 DOI: 10.3390/pathogens12050742] [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: 04/16/2023] [Revised: 05/09/2023] [Accepted: 05/09/2023] [Indexed: 05/28/2023] Open
Abstract
Polymorphisms in the genes encoding the merozoite surface proteins msp-1 and msp-2 are widely used markers for characterizing the genetic diversity of Plasmodium falciparum. This study aimed to compare the genetic diversity of circulating parasite strains in rural and urban settings in the Republic of Congo after the introduction of artemisinin-based combination therapy (ACT) in 2006. A cross-sectional survey was conducted from March to September 2021 in rural and urban areas close to Brazzaville, during which Plasmodium infection was detected using microscopy (and nested-PCR for submicroscopic infection). The genes coding for merozoite proteins-1 and -2 were genotyped by allele-specific nested PCR. Totals of 397 (72.4%) and 151 (27.6%) P. falciparum isolates were collected in rural and urban areas, respectively. The K1/msp-1 and FC27/msp-2 allelic families were predominant both in rural (39% and 64%, respectively) and urban (45.4% and 54.5% respectively) areas. The multiplicity of infection (MOI) was higher (p = 0.0006) in rural areas (2.9) compared to urban settings (2.4). The rainy season and the positive microscopic infection were associated with an increase in MOI. These findings reveal a higher P. falciparum genetic diversity and MOI in the rural setting of the Republic of Congo, which is influenced by the season and the participant clinical status.
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Affiliation(s)
- Marcel Tapsou Baina
- Fondation Congolaise Pour la Recherche Médicale, Villa D6-Cité OMS-Djoué, Brazzaville BP69, Brazzaville BP69, Congo
- Département de Biologie Cellulaire et Moléculaire, Faculté des Sciences et Techniques, Université Marien Ngouabi, Brazzaville BP69, Congo
| | - Abel Lissom
- Fondation Congolaise Pour la Recherche Médicale, Villa D6-Cité OMS-Djoué, Brazzaville BP69, Brazzaville BP69, Congo
- Department of Zoology, Faculty of Science, University of Bamenda, Bambili P.O. Box 39, Cameroon
| | - Naura Veil Assioro Doulamo
- Fondation Congolaise Pour la Recherche Médicale, Villa D6-Cité OMS-Djoué, Brazzaville BP69, Brazzaville BP69, Congo
- Département de Biologie Cellulaire et Moléculaire, Faculté des Sciences et Techniques, Université Marien Ngouabi, Brazzaville BP69, Congo
| | - Jean Claude Djontu
- Fondation Congolaise Pour la Recherche Médicale, Villa D6-Cité OMS-Djoué, Brazzaville BP69, Brazzaville BP69, Congo
| | - Dieu Merci Umuhoza
- Fondation Congolaise Pour la Recherche Médicale, Villa D6-Cité OMS-Djoué, Brazzaville BP69, Brazzaville BP69, Congo
- Département de Biologie Cellulaire et Moléculaire, Faculté des Sciences et Techniques, Université Marien Ngouabi, Brazzaville BP69, Congo
| | - Jacques Dollon Mbama-Ntabi
- Fondation Congolaise Pour la Recherche Médicale, Villa D6-Cité OMS-Djoué, Brazzaville BP69, Brazzaville BP69, Congo
- Département de Biologie Cellulaire et Moléculaire, Faculté des Sciences et Techniques, Université Marien Ngouabi, Brazzaville BP69, Congo
| | - Steve Diafouka-Kietela
- Fondation Congolaise Pour la Recherche Médicale, Villa D6-Cité OMS-Djoué, Brazzaville BP69, Brazzaville BP69, Congo
| | - Jolivet Mayela
- Fondation Congolaise Pour la Recherche Médicale, Villa D6-Cité OMS-Djoué, Brazzaville BP69, Brazzaville BP69, Congo
| | - Georges Missontsa
- Fondation Congolaise Pour la Recherche Médicale, Villa D6-Cité OMS-Djoué, Brazzaville BP69, Brazzaville BP69, Congo
| | - Charles Wondji
- Department of Parasitology and Medical Entomology, Centre for Research in Infectious Diseases (CRID), Centre Region, Yaoundé P.O. Box 13501, Cameroon
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, L3 5QA Liverpool, UK
| | - Ayola Akim Adegnika
- Institute of Tropical Medicine, University Hospital of Tübingen, 72074 Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné, Lambaréné BP242, Gabon
- German Center for Infection Research (DZIF), partner site Tübingen, 72074 Tübingen, Germany
| | - Etienne Nguimbi
- Fondation Congolaise Pour la Recherche Médicale, Villa D6-Cité OMS-Djoué, Brazzaville BP69, Brazzaville BP69, Congo
- Département de Biologie Cellulaire et Moléculaire, Faculté des Sciences et Techniques, Université Marien Ngouabi, Brazzaville BP69, Congo
| | - Steffen Borrmann
- Institute of Tropical Medicine, University Hospital of Tübingen, 72074 Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné, Lambaréné BP242, Gabon
| | - Francine Ntoumi
- Fondation Congolaise Pour la Recherche Médicale, Villa D6-Cité OMS-Djoué, Brazzaville BP69, Brazzaville BP69, Congo
- Institute of Tropical Medicine, University Hospital of Tübingen, 72074 Tübingen, Germany
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Simons LM, Ferrer P, Gombakomba N, Underwood K, Herrera R, Narum DL, Canepa G, Acquah F, Amoah L, Duffy PE, Barillas-Mury C, Long C, Lee SM, Locke E, Miura K, Williamson KC. Extending the range of Plasmodium falciparum transmission blocking antibodies. Vaccine 2023; 41:3367-3379. [PMID: 37100721 PMCID: PMC10334573 DOI: 10.1016/j.vaccine.2023.04.042] [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: 12/01/2022] [Revised: 04/01/2023] [Accepted: 04/14/2023] [Indexed: 04/28/2023]
Abstract
Recent work demonstrating that asymptomatic carriers of P. falciparum parasites make up a large part of the infectious reservoir highlights the need for an effective malaria vaccine. Given the historical challenges of vaccine development, multiple parasite stages have been targeted, including the sexual stages required for transmission. Using flow cytometry to efficiently screen for P. falciparum gamete/zygote surface reactivity, we identified 82 antibodies that bound live P. falciparum gametes/zygotes. Ten antibodies had significant transmission-reducing activity (TRA) in a standard membrane feeding assay and were subcloned along with 9 nonTRA antibodies as comparators. After subcloning, only eight of the monoclonals obtained have significant TRA. These eight TRA mAbs do not recognize epitopes present in any of the current recombinant transmission-blocking vaccine candidates, Pfs230D1M, Pfs48/45.6C, Pf47 D2 and rPfs25. One TRA mAb immunoprecipitates two surface antigens, Pfs47 and Pfs230, that are expressed by both gametocytes and gametes/zygotes. These two proteins have not previously been reported to associate and the recognition of both by a single TRA mAb suggests the Pfs47/Pfs230 complex is a new vaccine target. In total, Pfs230 was the dominant target antigen, with five of the eight TRA mAbs and 8 of 11 nonTRA gamete/zygote surface reactive mAbs interacting with Pfs230. Of the three remaining TRA mAbs, two recognized non-reduced, parasite-produced Pfs25 and one bound non-reduced, parasite-produced Pfs48/45. None of the TRA mAbs bound protein on an immunoblot of reduced gamete/zygote extract and two TRA mAbs were immunoblot negative, indicating none of the new TRA epitopes are linear. The identification of eight new TRA mAbs that bind epitopes not included in any of the constructs currently under advancement as transmission-blocking vaccine candidates may provide new targets worthy of further study.
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Affiliation(s)
- Lacy M Simons
- Department of Biology, Loyola University Chicago, 1032 W Sheridan Rd, Chicago, IL 60660, USA
| | - Patricia Ferrer
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD, 20814, USA; Henry M. Jackson Foundation for the Advancement of Military Medicine, 6720A Rockledge Drive, Suite 100, Bethesda, USA
| | - Nita Gombakomba
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD, 20814, USA; Henry M. Jackson Foundation for the Advancement of Military Medicine, 6720A Rockledge Drive, Suite 100, Bethesda, USA
| | - Knashka Underwood
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD, 20814, USA
| | - Raul Herrera
- Vaccine Development Unit, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA
| | - David L Narum
- Vaccine Development Unit, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA
| | - Gaspar Canepa
- Mosquito Immunity and Vector Competence Section Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Rockville, MD 20852, USA
| | - Festus Acquah
- Immunology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Linda Amoah
- Immunology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Patrick E Duffy
- Vaccine Development Unit, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA
| | - Carolina Barillas-Mury
- Mosquito Immunity and Vector Competence Section Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Rockville, MD 20852, USA
| | - Carole Long
- Malaria Immunology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Rockville, MD 20852, USA
| | - Shwu-Maan Lee
- Center for Vaccine Innovation and Access, PATH, 455 Massachusetts Ave, NW, Suite 1000, Washington, DC, 20001, USA
| | - Emily Locke
- Center for Vaccine Innovation and Access, PATH, 455 Massachusetts Ave, NW, Suite 1000, Washington, DC, 20001, USA
| | - Kazutoyo Miura
- Malaria Immunology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Rockville, MD 20852, USA
| | - Kim C Williamson
- Department of Biology, Loyola University Chicago, 1032 W Sheridan Rd, Chicago, IL 60660, USA; Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD, 20814, USA.
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B-Cell Epitope Mapping of the Plasmodium falciparum Malaria Vaccine Candidate GMZ2.6c in a Naturally Exposed Population of the Brazilian Amazon. Vaccines (Basel) 2023; 11:vaccines11020446. [PMID: 36851323 PMCID: PMC9966924 DOI: 10.3390/vaccines11020446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 02/09/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023] Open
Abstract
The GMZ2.6c malaria vaccine candidate is a multi-stage P. falciparum chimeric protein that contains a fragment of the sexual-stage Pfs48/45-6C protein genetically fused to GMZ2, an asexual-stage vaccine construction consisting of the N-terminal region of the glutamate-rich protein (GLURP) and the C-terminal region of the merozoite surface protein-3 (MSP-3). Previous studies showed that GMZ2.6c is widely recognized by antibodies from Brazilian exposed individuals and that its components are immunogenic in natural infection by P. falciparum. In addition, anti-GMZ2.6c antibodies increase with exposure to infection and may contribute to parasite immunity. Therefore, identifying epitopes of proteins recognized by antibodies may be an important tool for understanding protective immunity. Herein, we identify and validate the B-cell epitopes of GMZ2.6c as immunogenic and immunodominant in individuals exposed to malaria living in endemic areas of the Brazilian Amazon. Specific IgG antibodies and subclasses against MSP-3, GLURP, and Pfs48/45 epitopes were detected by ELISA using synthetic peptides corresponding to B-cell epitopes previously described for MSP-3 and GLURP or identified by BepiPred for Pfs48/45. The results showed that the immunodominant epitopes were P11 from GLURP and MSP-3c and DG210 from MSP-3. The IgG1 and IgG3 subclasses were preferentially induced against these epitopes, supporting previous studies that these proteins are targets for cytophilic antibodies, important for the acquisition of protective immunity. Most individuals presented detectable IgG antibodies against Pfs48/45a and/or Pfs48/45b, validating the prediction of linear B-cell epitopes. The higher frequency and antibody levels against different epitopes from GLURP, MSP-3, and Pfs48/45 provide additional information that may suggest the relevance of GMZ2.6c as a multi-stage malaria vaccine candidate.
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Ivanochko D, Fabra-García A, Teelen K, van de Vegte-Bolmer M, van Gemert GJ, Newton J, Semesi A, de Bruijni M, Bolscher J, Ramjith J, Szabat M, Vogt S, Kraft L, Duncan S, Lee SM, Kamya MR, Feeney ME, Jagannathan P, Greenhouse B, Sauerwein RW, Richter King C, MacGill RS, Bousema T, Jore MM, Julien JP. Potent transmission-blocking monoclonal antibodies from naturally exposed individuals target a conserved epitope on Plasmodium falciparum Pfs230. Immunity 2023; 56:420-432.e7. [PMID: 36792575 PMCID: PMC9942874 DOI: 10.1016/j.immuni.2023.01.013] [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: 08/16/2022] [Revised: 11/04/2022] [Accepted: 01/12/2023] [Indexed: 02/16/2023]
Abstract
Pfs230 is essential for Plasmodium falciparum transmission to mosquitoes and is the protein targeted by the most advanced malaria-transmission-blocking vaccine candidate. Prior understanding of functional epitopes on Pfs230 is based on two monoclonal antibodies (mAbs) with moderate transmission-reducing activity (TRA), elicited from subunit immunization. Here, we screened the B cell repertoire of two naturally exposed individuals possessing serum TRA and identified five potent mAbs from sixteen Pfs230 domain-1-specific mAbs. Structures of three potent and three low-activity antibodies bound to Pfs230 domain 1 revealed four distinct epitopes. Highly potent mAbs from natural infection recognized a common conformational epitope that is highly conserved across P. falciparum field isolates, while antibodies with negligible TRA derived from natural infection or immunization recognized three distinct sites. Our study provides molecular blueprints describing P. falciparum TRA, informed by contrasting potent and non-functional epitopes elicited by natural exposure and vaccination.
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Affiliation(s)
- Danton Ivanochko
- Program in Molecular Medicine, the Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | | | - Karina Teelen
- Department of Medical Microbiology, Radboudumc, Nijmegen, the Netherlands
| | | | | | - Jocelyn Newton
- Program in Molecular Medicine, the Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Anthony Semesi
- Program in Molecular Medicine, the Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | | | | | - Jordache Ramjith
- Radboud Institute for Health Sciences, Department for Health Evidence, Biostatistics Section, Radboudumc, Nijmegen, the Netherlands
| | | | | | - Lucas Kraft
- AbCellera Biologics Inc., Vancouver, BC, Canada
| | | | - Shwu-Maan Lee
- PATH's Malaria Vaccine Initiative, Washington, DC 20001, USA
| | - Moses R Kamya
- Infectious Disease Research Collaboration, Kampala, Uganda
| | - Margaret E Feeney
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA; Department of Pediatrics, University of California, San Francisco, San Francisco, CA, USA
| | - Prasanna Jagannathan
- Department of Microbiology and Immunology, Stanford University, Stanford, CA, USA
| | - Bryan Greenhouse
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | | | - C Richter King
- PATH's Malaria Vaccine Initiative, Washington, DC 20001, USA
| | | | - Teun Bousema
- Department of Medical Microbiology, Radboudumc, Nijmegen, the Netherlands.
| | - Matthijs M Jore
- Department of Medical Microbiology, Radboudumc, Nijmegen, the Netherlands.
| | - Jean-Philippe Julien
- Program in Molecular Medicine, the Hospital for Sick Children Research Institute, Toronto, ON, Canada; Departments of Biochemistry and Immunology, University of Toronto, Toronto, ON, Canada.
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