Susceptibility to malaria in fulani, Bariba, Otamari and gando individuals living in sympatry in Benin: Role of opsonizing antibodies to Plasmodium falciparum merozoites

Objectives: Fulani in Africa are known to be less susceptible to Plasmodium falciparum (Pf) malaria. This study explored a potential involvement of antibody-mediated merozoite phagocytosis mechanism in this natural protection against malaria.Methods: Before the start of the malaria transmission season (MTS) in Benin, the functionality of antibodies against Pf merozoites was determined by the opsonic phagocytosis (OP) assay in plasma samples from Fulani, Bariba, Otamari and Gando groups. These individuals were actively followed-up for malaria detection from the beginning to the end of MTS. Anti-GLURP Immuno-globulin G antibody quantification, malaria Rapid Diagnostic Test (RDT) and spleen palpation were performed before and after MTS.Results: In Bariba, Otamari and Gando, but not in Fulani, plasma from adults promoted higher levels of OP than the children (P = 0.003; P = 0.012; P = 0.031 and P = 0.122). A high proportion of Fulani children had higher OP and anti-GLURP (P < 0.0001) antibody levels as compared to non-Fulani children; whereas this was not observed for Fulani adults (P = 0.223). High OP levels before MTS were significantly related to negative RDT after MTS (P = 0.011).Conclusion: Our results highlight the ability of opsonizing antibodies to potentially enhance natural protection of young Fulani individuals against Pf malaria in Benin.

Automated summary

This study explores a potential mechanism of natural protection against malaria in the Fulani population, suggesting that antibody-mediated merozoite phagocytosis may play a role. Results show that adults from the Bariba, Otamari, and Gando groups have higher levels of opsonic phagocytosis compared to children, while the Fulani population shows the opposite trend. Fulani children have higher levels of opsonic phagocytosis and anti-GLURP antibodies compared to non-Fulani children, with no significant difference observed in Fulani adults. Higher levels of opsonic phagocytosis before the malaria transmission season are associated with negative malaria Rapid Diagnostic Test results after the season.