Analysis of phylogeographic and immunological relationship in Plasmodium malariae and Plasmodium brasilianum

Abstract

In Brazil, 99.7% of malaria cases occur in the Amazon Region, where Plasmodium vivax, Plasmodium falciparum and Plasmodium malariae are present. In the Extra-Amazon Region, malaria transmission prevails in Atlantic Forest areas. Autochthonous cases of this region, which are caused by P. vivax or P. malariae, have mostly low parasitemia and asymptomatic presentation. It is supposed that malaria in the Atlantic Forest is a zoonosis, since genetic evidences demonstrate that P. malariae is derived from P. brasilianum, a parasite that causes malaria in non-human primates. P. malariae is a parasite with a wide-range geographic distribution, and is probably one of the most ancient agents of malaria. However, due to its morphological similarity with P. vivax, its prevalence has been underestimated. This work aims to shed light on prevalence and distribution of P. malariae and P. brasilianum in Brazil, and its genetic and immunological relationship. Genetic analysis will be performed using complete mitochondrial genome sequencing of the isolates obtained. For the immunological relationship analysis, serologic assays, using recombinant proteins derived from different regions of MSP1 (merozoite surface protein 1), will be performed. This protein was chosen because it is very polymorphic and antigenic in natural infections caused by P. vivax and P. falciparum. However, up to now, there are no serological studies with field isolates of non-human primates using MSP1 from P. brasilianum. For P. malariae, there is only one study, accomplished out of Brazil, where MSP119 was tested in a few number of human field isolates of unknown geographic origin. Here, thus, we intend to test the antibody response against seven recombinant proteins produced with MSP1 sequences from P. malariae and P. brasilianum. Serum samples of humans and non-human primates from different Brazilian endemic regions (Amazon and Atlantic Forest Region) will be analyzed. This research will be done using ELISA and Bioplex, allowing a comparison of the results obtained from these different methods. (AU)