Perfil da resposta igg3 contra painel de proteínas variantes do bloco 2 da msp1 prediz malária vivax assintomática: Produção de antígenos recombinantes variantes do bloco-2 da PvMSP1 para avaliação da resposta humoral de individuos residentes na comunidade Rio Pardo, região endêmica para malária no Amazonas

Abstract

Malaria is a serious problem health public worldwide, where 3.2 billion people live in areas at risk, infections malaria with Plasmodium vivax widely distributed in the Americas and accounting for 80% of cases in Brazil. The last decade witnessed major advances in strategies to combat and eliminate global malaria, which culminated in a decline in the number of cases reported and deaths. These advances have brought optimism to the achievement of ambitious targets, such as the global reduction in at least 90% of malaria cases and mortality rates by 2030. Among the challenges to be overcome is the tracking of asymptomatic cases, since despite the lack of symptoms and low parasitemia, these individuals are parasitic reservoirs and contribute to the incidence of malaria. As a strategy, the capture of antigen-specific malaria antibodies, using antigens polymorphic, is an effective tool for the detection of asymptomatic cases, because of their greater coverage and the possibility of recognition of antigen-specific antibodies. Given this, the present work evaluated a panel of variant proteins, based on the polymorphism of the Block 2 region of Plasmodium vivax Merozoite Surface Protein-1 (PvMSP1) for the investigation of antigens specific as a method of identifying asymptomatic malaria individuals by P. vivax. Were produced five proteins recombinant variant the Block-2 of PvMSP1 (P2, P4, P5, P6 and P5), for the investigation of antibodies antigen-specific and quantification of IgG total and subclasse (IgG1, IgG2 and IgG3), in serum from individuals with vivax malaria asymptomatic, symptomatic and non-infected. Total IgG levels were quantified for each protein variant (P2, P4, P5, P6 and P7) and all sérum responded to at least one protein, but at different levels. The characterization of the subclasses indicated that IgG1 and IgG3 were predominant in the response against the variants, while the IgG2 subclass showed low reactivity. From this point, individuals uninfected the subclass IgG1 showed predominant that was at least with the P2, P4, P5 and P6 proteins. While IgG3 was more prevalent in the asymptomatic and less frequent in the group of uninfected individuals. Considering the sensitivity and specificity of each protein for detecting total and subclass IgG levels and thus predicting which proteins to use to differentiate the group from asymptomatic non-infected individuals, we saw that P2 would be a promising protein, showing 100% sensitivity to capture IgG antibodies and the IgG3 subclass and have a specificity of 76% for IgG3. The values of likelihood ratios of individuals asymptomatic with seropositivity IgG total and subclasses IgG3 for proteins P4, P5 and P7 showed important predictive values. Conclusion: Our findings revealed that the panel of variants Block 2 of the PvMSP-1 serology and subclasses specific IgG can guide the rational use to create a tool for detection of asymptomatic cases of vivax malaria as a strategy for elimination of malaria.