Studying the disease severity in clinical isolates of Plasmodiumvivax

Abstract

Among the human malaria Plasmodium species, Plasmodium vivax is the most widespread species globally. In recent times, this historically benign species is now being recognized as also responsible for severe malaria infections in humans. Hence, a deeper insight of P.vivax immunopathogenesis in clinical patients is essential for malaria control and elimination strategies. Certain genes like vir genes, merozoite surface protein 3α genes (msp3α) and biomarkers like super oxide dismutase (SOD-1), tumor necrosis factor (TNF- α), interleukin (IL-10) are speculated to have some role in disease severity and thus can be useful as diagnostic markers. In the reported study, the clinical samples of P.vivax were genotyped for msp3α gene and cytokine analysis, expression profiling of vir genes were also carried out in these samples. A total of 84 P.vivax samples were collected (39 severe and 45 non-severe samples) and no correlation of parasitemia with severity of disease was seen in these samples (p-value = 0.38). On analysis four genotypes of msp3α were found, with type B (1.5 kb) as the predominant genotype. Cytokine analysis revealed SOD-1 and TNF-α levels to be significantly more in the severe group than in non-severe group, whereas for IL-10 no significant difference was observed between two clinical groups. The vir gene profiling revealed increased level of expression for vir-12, vir-14 related, and vir-17 like in severe group and vir-10 related gene expression was more in non-severe samples. There are multiple factors that bring phenotypic and genotypic changes in P.vivax malaria and thus, it is important to assess the potential diagnostic markers for detection of disease severity. In future, studies with more number of clinical samples should be undertaken for better insight of P.vivax disease severity.