Plasmodium vivax: whole transcriptome shotgun sequencing data analysis

• Grant number: 16/11764-0
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: October 10, 2016
• End date: June 09, 2017
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal Investigator: Fabio Trindade Maranhão Costa
• Grantee: Catarina Baeta da Luz Bourgard
• Supervisor: Per Sunnerhagen
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Institution abroad: University of Gothenburg, Sweden
• Associated to the scholarship: 13/20509-5 - Analyses of the immunopathological and molecular mechanisms involved in cytoadherence of Plasmodium vivax, BP.DR

Abstract

The way researchers tackle problems have changed significantly in the last decade, with sequencing revolutionizing omics field in biological research. What was unthinkable to ask before, is now made easier and available for us to grasp and use in our never-ending quest for knowledge on the most complex biological questions. By enhancing our awareness in basic parasite molecular biology, its ecology and epidemiology, Whole Genome Sequencing (WGS) has already greatly benefited parasitology research. Malariology stands out, wherein extraordinary progresses achieved in Plasmodium spp. biology. Considering the several human malaria species, the prevalent, widespread and neglected Plasmodium vivax is currently placing billions of people at risk of infection, imposing major health and economic burdens. Worldwide, heterogeneous anti-malarial drug resistance and severe clinical complications are of great concern and could be associated to parasite cytoadherence. In the 60s, P. vivax sequester capacity was proposed, whereas a disproportional low level of mature blood stages (schizonts) relative to young stages (trophozoites) was found in patients peripheral blood circulation, indicating that maturation of P. vivax could occur deep in the human microvasculature. We were the first to demonstrate that P. vivax infected erythrocytes, collected from natural vivax malaria patients, were capable to adhere ex vivo to cells and also, we confirmed the lower rate of peripheral circulating schizonts in P. vivax infected patients. As well, we were able to demonstrate that schizont have a higher adhesion capacity relative to the same P. vivax isolates before maturation. This data suggests that less schizonts observation could be a consequence of P. vivax sequestration, leading to higher disease severity. P. vivax research community faces great hurdles to uncover the biology of this elusive parasite, posing huge hitches for control policies decision-making. The lack of a reliable in vitro P. vivax long term culture20, restricts the study of its biology in place and time, with researchers working in challenging malaria endemic field conditions. Thus, little is known about the genetic background somewhat involved in the P. vivax cytoadhesion. Reference genome P. vivax Sal-1 primate adapted strain WGS has opened new avenues for molecular biology and evolutionary studies, but transcriptome studies aiming to grasp the molecular mechanisms underlying several aspects of P. vivax pathogenesis are lacking. Whole Transcriptome Shotgun Sequencing (WTSS), commonly known by RNA-seq, is a powerful approach to help us in identifying strain specific patterns of gene expression associated with P. vivax virulence and host-pathogen interactions. Besides, comparative transcriptome analysis between the deadly P. falciparum and P. vivax would be key to access the biological and clinical differences between this human malaria parasite species, impacting considerably in vaccines and drug designs. The low parasitemias, multi-clonality and host contaminations of a natural isolate are some of the limitations being currently overcome by enriching and maturing ex vivo P. vivax clinical isolates. Successful RNA isolation of a panel of P. vivax field isolates with scarce parasitemia, enriched in (cyto-)adhesion phenotypes from Amazon malaria endemic region already allowed us to complete the generation of transcriptomic libraries, ready for next generation sequencing (NGS) using the Illumina® platform. We hope that such achievements will further open the investigations on the biology of P. vivax apicomplexan parasite, so as to succeed vivax malaria eradication in the future. (AU)