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Wang LT, Pereira LS, Kiyuka PK, Schön A, Kisalu NK, Vistein R, Dillon M, Bonilla BG, Molina-Cruz A, Barillas-Mury C, Tan J, Idris AH, Francica JR, Seder RA. Protective effects of combining monoclonal antibodies and vaccines against the Plasmodium falciparum circumsporozoite protein. PLoS Pathog 2021; 17:e1010133. [PMID: 34871332 PMCID: PMC8675929 DOI: 10.1371/journal.ppat.1010133] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 12/16/2021] [Accepted: 11/19/2021] [Indexed: 11/18/2022] Open
Abstract
Combinations of monoclonal antibodies (mAbs) against different epitopes on the same antigen synergistically neutralize many viruses. However, there are limited studies assessing whether combining human mAbs against distinct regions of the Plasmodium falciparum (Pf) circumsporozoite protein (CSP) enhances in vivo protection against malaria compared to each mAb alone or whether passive transfer of PfCSP mAbs would improve protection following vaccination against PfCSP. Here, we isolated a panel of human mAbs against the subdominant C-terminal domain of PfCSP (C-CSP) from a volunteer immunized with radiation-attenuated Pf sporozoites. These C-CSP-specific mAbs had limited binding to sporozoites in vitro that was increased by combination with neutralizing human “repeat” mAbs against the NPDP/NVDP/NANP tetrapeptides in the central repeat region of PfCSP. Nevertheless, passive transfer of repeat- and C-CSP-specific mAb combinations did not provide enhanced protection against in vivo sporozoite challenge compared to repeat mAbs alone. Furthermore, combining potent repeat-specific mAbs (CIS43, L9, and 317) that respectively target the three tetrapeptides (NPDP/NVDP/NANP) did not provide additional protection against in vivo sporozoite challenge. However, administration of either CIS43, L9, or 317 (but not C-CSP-specific mAbs) to mice that had been immunized with R21, a PfCSP-based virus-like particle vaccine that induces polyclonal antibodies against the repeat region and C-CSP, provided enhanced protection against sporozoite challenge when compared to vaccine or mAbs alone. Collectively, this study shows that while combining mAbs against the repeat and C-terminal regions of PfCSP provide no additional protection in vivo, repeat mAbs do provide increased protection when combined with vaccine-induced polyclonal antibodies. These data should inform the implementation of PfCSP human mAbs alone or following vaccination to prevent malaria infection. The Plasmodium falciparum (Pf) circumsporozoite protein (CSP) is the major surface protein on sporozoites and is required for these malaria parasites to invade the liver. Antibodies can prevent malaria by neutralizing sporozoites prior to liver invasion. The only approved malaria vaccine (RTS,S) is comprised of the repeat region and C-terminus of PfCSP. RTS,S-mediated protection is associated with vaccine-induced antibodies against both regions. While monoclonal antibodies (mAbs) against the three tetrapeptides in the repeat region potently bind and neutralize sporozoites, mAbs against the C-terminus demonstrate limited sporozoite binding and neutralization. Here, we used flow cytometry to show that the sporozoite binding of C-terminal mAbs are potentiated by combining them with repeat mAbs. This in vitro synergy did not translate into enhanced in vivo protection against sporozoite challenge in mice treated with repeat and C-terminal mAb combinations. Furthermore, combining mAbs against the three tetrapeptides in the repeat region did not provide enhanced protection against sporozoite challenge compared to each mAb alone. However, combining passive and active immunization with repeat mAbs and a RTS,S-like vaccine improved protection against sporozoite challenge compared to each intervention alone. These results have important implications for implementing anti-PfCSP mAbs alone or in combination with vaccines to prevent malaria.
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Affiliation(s)
- Lawrence T. Wang
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Lais S. Pereira
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Patience K. Kiyuka
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- Department of Biological Sciences, Pwani University, Kilifi, Kenya
| | - Arne Schön
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Neville K. Kisalu
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Rachel Vistein
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Marlon Dillon
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Brian G. Bonilla
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Alvaro Molina-Cruz
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Carolina Barillas-Mury
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Joshua Tan
- Antibody Biology Unit, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Azza H. Idris
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- The Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology and Harvard University, Cambridge, Massachusetts, United States of America
| | - Joseph R. Francica
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Robert A. Seder
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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