Produção de antígenos recombinantes de regiões polimórficas e conservada da “proteína 1” de superfície de merozoíto de plasmodium vivax e caracterização da resposta imune humoral em indivíduos expostos a malária no Amazonas

Abstract

Introduction: Malaria is a public health issue distributed in tropical and subtropical regions worldwide. In Brazil, the disease still has a high number of cases in which Plasmodium vivax (P. vivax) is responsible for most of diagnosis. Lately, these cases have been performing so complicated that becomes a matter of concern because the species has a wide geographic distribution, and there is a need to control the infection. One alternative for infection control would be the development of a vaccine. However, a major problem for its development is the lack of understanding of the immune response against the antigen candidates. Among the candidate antigens, the Protein 1 Merozoite Surface (MSP-1) of Plasmodium has excelled, because studies show that antibodies against different regions of MSP-1 confer clinical protection in individuals living in endemic areas. The aim of this study was to characterize the humoral immune response against the recombinant antigen of conserved and variable regions of PvMSP-1 in individuals living in endemic areas in the state of Amazonas. Methods: For this purpose, we produced three recombinant proteins, two corresponding to the variable region (block 2) and the conserved (block ICB1) of PvMSP-1 (using sequences identified by previous workers, and selected by bioinformatics as epitopes B cell). The proteins were expressed and purified using synthetic genes optimized for expression in Escherichia coli. The serum reactivity from symptomatic and asymptomatic patients against the proteins was evaluated by ELISA, along with protein ICB2 PvMSP-5-1 (obtained in previous work. Results and Conclusion: The expression and purification of recombinant proteins were performed successfully. The serological analysis against recombinant antigens showed a higher level of antibodies against the protein ICB2-5 for both groups (Rio Pardo and Manaus). Regarding IgG antibody response against the three proteins (P1, P2 and P3), it was observed that the P2 protein was recognized in the serum of most patients symptomatic of Manaus and Rio Pardo, whereas P3 has been the most recognized in asymptomatic . The subclasses analysis showed that the IgG3 was the most prevalent against ICB2-5. The level of reactivity was low to subclasses for all proteins, but when the frequencies of serum IgG2 and IgG3 responders were assembled in silico (ICB2-5 + P1 + P2 + P3). These results recognition level overcame ICB2-5 alone, suggesting that the development of the repertoire of recombinant proteins corresponding to block 2 is capable to expand the spectrum of reactive serum.