Plasmodium vivax: transcriptomic analysis

In the last decade, scientific problems have been approached differently through the application of new technologies. Complex biological questions once considered impossible to unravel are now being explored in the pursuit of knowledge. Next-generation sequencing (NGS) has greatly advanced the understanding of molecular biology, ecology, and parasite epidemiology. In malaria research, notable progress has been achieved in the study of the genus Plasmodium. Among the several species that cause human malaria, the neglected and geographically widespread Plasmodium vivax places millions of people at risk, exerting a significant social and economic impact. Reports of heterogeneous resistance to antimalarials and increased disease severity highlight the need to study the immunopathogenesis and biology of P. vivax, including its ability to adhere. The evasion capacity of P. vivax was proposed in the 1960s when a disproportion between mature (schizonts) and young (trophozoites) parasitic stages was observed in the peripheral blood of infected patients, suggesting that parasite maturation might occur within the human microvasculature. Indeed, in ex vivo assays, the research team demonstrated that erythrocytes infected by P. vivax can adhere to lung, brain, and placental endothelium. Furthermore, recent findings of a low frequency of circulating schizonts and a high adhesive capacity of these forms indicate that these parasites may be “sequestered” in the microvasculature, contributing to increased disease severity. Research on P. vivaxmalaria faces numerous experimental challenges in understanding the parasite’s biology, which complicates decision-making and the implementation of effective disease control and transmission strategies. Studies on P. vivax biology and pathogenesis remain limited, primarily due to the inability to continuously culture the parasite. Consequently, ex vivo functional assays using blood forms collected from infected patients are restricted to endemic areas, and little is known about the molecular mechanisms underlying P. vivax adhesion. The sequencing of the reference genome of the primate-adapted P. vivax Sal-1 strain has opened new avenues in molecular biology, but transcriptomic studies aimed at elucidating the molecular mechanisms of P. vivax pathogenesis remain scarce. Transcriptome sequencing (RNA-seq) has proven to be a powerful tool for identifying specific expression patterns associated with virulence and for characterizing host-pathogen interactions. Comparative analyses between P. falciparum and P. vivax transcriptomes are expected to reveal biological and clinical differences between these two major human malaria species, with important implications for the design of future drugs and vaccines. Experimental limitations such as low parasitemia, infection multiclonality, and contamination with host genetic material have been mitigated using enrichment techniques and ex vivo maturation of P. vivax. As a result of this project, the research team successfully isolated RNA from a panel of P. vivax clinical isolates from the Brazilian Amazon, characterized by low parasitemia and enriched in (cyto)adhesion phenotypes. The generation of transcriptomic libraries, ready for sequencing on an Illumina® NGS platform, has been successfully completed. The expectation is that this work will open new opportunities for advancing the understanding of this apicomplexan parasite’s biology, ultimately contributing to more effective strategies for combating P. vivax malaria with the goal of its eventual elimination.

Project details

Enabling Technologies & Assays
Genetics and Genomics

Oct 2016 — Jun 2017

Brazil