Thongpoon S, Roobsoong W, Nguitragool W, Chotirat S, Tsuboi T, Takashima E, Cui L, Ishino T, Tachibana M, Miura K, Sattabongkot J. Naturally Acquired Transmission-Blocking Immunity Against Different Strains of Plasmodium vivax in a Malaria-Endemic Area in Thailand.
J Infect Dis 2024;
229:567-575. [PMID:
37943633 PMCID:
PMC10873188 DOI:
10.1093/infdis/jiad469]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 09/30/2023] [Accepted: 11/04/2023] [Indexed: 11/12/2023] Open
Abstract
BACKGROUND
Human immunity triggered by natural malaria infections impedes parasite transmission from humans to mosquitoes, leading to interest in transmission-blocking vaccines. However, immunity characteristics, especially strain specificity, remain largely unexplored. We investigated naturally acquired transmission-blocking immunity (TBI) against Plasmodium vivax, a major malaria parasite.
METHODS
Using the direct membrane-feeding assay, we assessed TBI in plasma samples and examined the role of antibodies by removing immunoglobulins through protein G/L adsorption before mosquito feeding. Strain specificity was evaluated by conducting a direct membrane-feeding assay with plasma exchange.
RESULTS
Blood samples from 47 patients with P vivax were evaluated, with 37 plasma samples successfully infecting mosquitoes. Among these, 26 showed inhibition before immunoglobulin depletion. Despite substantial immunoglobulin removal, 4 samples still exhibited notable inhibition, while 22 had reduced blocking activity. Testing against heterologous strains revealed some plasma samples with broad TBI and others with strain-specific TBI.
CONCLUSIONS
Our findings indicate that naturally acquired TBI is mainly mediated by antibodies, with possible contributions from other serum factors. The transmission-blocking activity of plasma samples varied by the tested parasite strain, suggesting single polymorphic or multiple targets for naturally acquired TBI. These observations improve understanding of immunity against P vivax and hold implications for transmission-blocking vaccine development.
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