Résumé
A decreased susceptibility of Fulani populations to malaria infections has been shown in Africa. A previous longitudinal cohort study conducted in the Atacora region of northern Benin showed a high merozoitephagocytosis capacity in young Fulani. Here, we explored the combined polymorphisms in the constant region of the IgG3 heavy chain (presence/absence of the G3m6 allotype) and in Fc gamma receptors (Fc?Rs) as potentially involved in the natural protection against malaria of young Fulani in Benin. An active malaria followup was conducted among individuals from Fulani, Bariba, Otamari and Gando ethnic groups living in sympatry in Atacora, over the full malaria transmission season. Fc?RIIA 131R/H (rs1801274), Fc?RIIC C/T (rs3933769) and Fc?RIIIA 176F/V (rs396991) were determined using the TaqMan method; Fc?RIIIB NA1/NA2 was assessed by polymerase chain reaction (PCR) using allele-specific primers and G3m6 using allotype by PCR-RFLP. Individual carriage of G3m6 (+) was associated with an increased risk of Pf malaria infection (logistic multivariate regression model (lmrm), OR = 2.25, 95% CI = 1.06;4.74, P = 0.034). Combined haplotype G3m6 (+) - Fc?RIIA 131H - Fc?RIIC T - Fc?RIIIA 176F - Fc?RIIIB NA2 was also associated with an increased risk of Pf malaria infection (lmrm, OR =13.01, 95% CI =1.69;99.76, P = 0.014). G3m6 (-), Fc?RIIA 131R and Fc?RIIIB NA1 were more prevalent in young Fulani (P = 0.002, P < 0.001 and P = 0.049, respectively), while no Fulani presented the combined G3m6 (+) - Fc?RIIA 131H - Fc?RIIC T - Fc?RIIIA 176F - Fc?RIIIB NA2 haplotype that was carried by a majority of infected children. Our results highlight the combined factors G3m6 - Fc?R as potentially involved in the merozoite-phagocytosis capacity and in the natural protection of young Fulani individuals against P. falciparum malaria in Benin.