Perfil de anticorpos contra diferentes antígenos recombinantes de merozoítos de Plasmodium vivax e sua associação à morbidade

Abstract

Since antimalarial immunity to the antigen repertoire of Plasmodium is complex and comprises distinct but interacting components, an important step before design a vaccine is identifying the precise nature of immune responses that function as targets of naturally acquired antibodies. In an effort to identify such targets, we investigated specific antibody responses against two Plasmodium vivax valuable vaccine candidates, PvMSP-119 and PvMSP-3, as well as their relationship with anemia and thrombocytopenia in P. vivax infected patients. Overall, PvMSP-119 was the most immunogenic antigen, and the frequency of responders to this protein tended to increase in patients with higher parasitaemia. For bothantigens, IgG antibody responses tended to be lower in patients who had experienced their first malaria. Univariate analysis revealed that anemic patients presented higher IgG antibody responses to PvMSP-3 than non-anemic ones. The joint effects of different IgG isotypes were further evaluated by robust multivariate analysis, aiming to detect the antibody profile that could be involved in anemia. Anemic patients presented higher levels of IgG1/IgG2/IgG3/IgG4 anti-MSP3 than non-anemic ones. As PvMSP-3 is a secreted polymorphic antigen, we hipothesized that it could adhere to uninfected or infected erytocytes, resulting in IgG or complement binding and accelerating the destruction of normalerythrocytes. These data may add important information for understanding the immunological aspects involved in pathogenesis of vivax malaria.