Identification of Highly Expressed Plasmodium Vivax Proteins from Clinical Isolates Using Proteomics.

Plasmodium vivax is the most geographically widespread species responsible for malaria in humans. Our study focused on identifying highly expressed parasite proteins using a shotgun proteomics approach. Parasites (P. vivax) are isolated from seven patient samples using saponin lysis. Protein extracts from these parasites are processed and subjected to LC-MS/MS analysis. An overall proteome coverage of 605 P. vivax proteins along with 1670 human host proteins are obtained upon combining the data from LC-MS/MS runs. While a major proportion of the P. vivax proteins are either hypothetical or involved in basic cellular activities, few proteins such as tryptophan-rich antigen (Pv-fam-a; PVX_090265), Pv-fam-d protein (PVX_101520), Plasmodium exported protein (PVX_003545), Pvstp1 (PVX_094303) and hypothetical protein (PVX_083555) are detected in more than 80% of the clinical isolates and found to be unique to P. vivax without orthologs in P. falciparum. Our proteomics study on individual parasite isolates reveals highly expressed P. vivax proteins, few of which may be good candidates for vivax malaria diagnosis due to their abundance and absence in P. falciparum. This study represents the first step towards the identification of biomarkers for P. vivax malaria. In future, their clinical diagnostic values must be explored and validated on large patient cohorts.