Dados do Trabalho

Título

CHARACTERIZATION OF CELLULAR AND HUMORAL IMMUNE RESPONSE TO P. vivax CYSTEINE-RICH PROTECTIVE ANTIGEN (PvCyRPA) IN INDIVIDUALS FROM THE BRAZILIAN AMAZON

Introdução

Malaria is caused by Plasmodium parasites and is responsible for thousands of deaths around the globe. CyRPA is a protein present in merozoite micronemes that participates in erythrocyte invasion. In P. falciparum, recombinant CyRPA induced protective antibodies in preclinical in vitro and in vivo models. In P. vivax, naturally acquired antibodies against PvCyRPA were associated with reduction of symptomatic infections in children. However, studies on the cellular and humoral response against PvCyRPA weren’t carried out in the Amazon, as well as T and B cell epitope identification.

Objetivo(s)

Characterize the naturally acquired immune response to PvCyRPA, identifying B and T cell epitopes and their association with indicatives of exposure and/or protection

Material e Métodos

To evaluate IgM and IgG immune response, plasma samples from P. vivax infected individuals (N=30), exposed individuals with previous P. vivax infections (N=30), exposed subjects with no reported infections in the last 10 years (N=30) and unexposed controls (N=10) were used against recombinant PvCyRPA and 7 most well-scored potential B-cell epitopes by in silico prediction. Finally, T-cell epitopes predicted to be promiscuous and immunogenic in PvCyRPA (N=10) were used as stimuli, in different pools, using PBMCs of all study subjects in IFN-γ Elispot.

Resultados e Conclusão

From 90 plasma samples tested, 42 individuals were reactive for IgM (46.7%) and 45 for IgG (50%). From these 23 individuals presented both IgM and IgG antibodies (25.6%) against PvCyRPA. Comparing IgM and IgG responses among groups (N=30 per group), it was observed a higher frequency of IgM antibodies in the infected group (N=26, 86.7%) in comparison to exposed groups (N=8, 26.7% in both groups) (p<0.0001). Recombinant PvCyRPA Elisa assays were performed to evaluate IgG subclasses using IgG responders (N=45). These results demonstrated a predominance of the cytophilic subclasses IgG1 (N=28, 62.2%) and IgG3 (N=25, 55.6%). Elispot assays were performed using different pool combinations of T cell peptides to stimulate PBMCs and 6 tested pools were able to induce INF- γ in infected individuals. Based on these preliminary results, PvCyRPA is naturally immunogenic in the study population and T-cell epitopes were able to induce IFN- γ secretion in PBMCs of infected individuals. These preliminary data reinforce the potential of PvCyRPA as a vaccine candidate, however more studies are still in progress to confirm B and T cell epitopes.

Palavras-chave

P. vivax, PvCyRPA, Malaria, Vaccine