Genetic diversity and immunogenicity analysis of MAEBL among Plasmodium vivax field isolates

Background:Plasmodium vivax is the most prevalent malaria species in Brazil. While the development of vaccines against falciparum malaria has been intense, fewer efforts have been made for P. vivax. The MAEBL M2 domain is involved in the erythrocyte binding and invasion and it is present in different stages of infection. This protein is present in different Plasmodiumspecies. An ideal malaria vaccine might be based on conserved antigens that induce broadly efficacious antibodies. In this light, we intend to analyze de genetic diversity of MAEBL from Plasmodium vivaxisolates as well evaluate the immunogenicity of this protein. Methods: DNA extractions from 10 isolates from three Amazon areas were performed. MAEBL-M2 domain was amplified, sequenced and aligned to other 49 sequences deposited in PlasmoDB. The M2-domain was expressed in Arctic Express (DE3) and the protein was tested in ELISA to investigate the immune response to MAEBL in the plasma of 97 symptomatic patients from Brazilian Amazon. Samples were collected in accordance with relevant guidelines and regulations of the ethics committee of the FMT-HVD (CAAE-0044.0.114.000-11). Results and Conclusions: In the alignment performed with 10 MAEBL-M2 domain sequences from Brazil, only one amino acid change was observed. When we compared the Brazilian sequences to other 49 sequences for other countries, we observed 7 amino acid changes and some of them were repeated in parasites from distant locations. The specific response of total IgG and IgM against MAEBL-M2 was evaluated in 100 plasma samples from symptomatic individuals infected with P. vivax from Manaus, Brazil. The prevalence of response for IgM was 4,34%. While the prevalence to total IgG was 56,7%. In conclusion, the results have showed that this antigen is highly conserved and immunogenic, reaffirming its potential as a vaccine candidate.