AUTHOR=Ford Anthony , Kepple Daniel , Williams Jonathan , Kolesar Gabrielle , Ford Colby T. , Abebe Abnet , Golassa Lemu , Janies Daniel A. , Yewhalaw Delenasaw , Lo Eugenia 

TITLE=Gene Polymorphisms Among Plasmodium vivax Geographical Isolates and the Potential as New Biomarkers for Gametocyte Detection

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=11

YEAR=2022

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2021.789417

DOI=10.3389/fcimb.2021.789417

ISSN=2235-2988

ABSTRACT=<p>The unique biological features of <italic>Plasmodium vivax</italic> not only make it difficult to control but also to eliminate. For the transmission of the malaria parasite from infected human to the vector, gametocytes play a major role. The transmission potential of a malarial infection is inferred based on microscopic detection of gametocytes and molecular screening of genes in the female gametocytes. Microscopy-based detection methods could grossly underestimate the reservoirs of infection as gametocytes may occur as submicroscopic or as micro- or macro-gametocytes. The identification of genes that are highly expressed and polymorphic in male and female gametocytes is critical for monitoring changes not only in their relative proportions but also the composition of gametocyte clones contributing to transmission over time. Recent transcriptomic study revealed two distinct clusters of highly correlated genes expressed in the <italic>P. vivax</italic> gametocytes, indicating that the male and female terminal gametocytogeneses are independently regulated. However, the detective power of these genes is unclear. In this study, we compared genetic variations of 15 and 11 genes expressed, respectively, in the female and male gametocytes among <italic>P. vivax</italic> isolates from Southeast Asia, Africa, and South America. Further, we constructed phylogenetic trees to determine the resolution power and clustering patterns of gametocyte clones. As expected, <italic>Pvs</italic>25 (PVP01_0616100) and <italic>Pvs</italic>16 (PVP01_0305600) expressed in the female gametocytes were highly conserved in all geographical isolates. In contrast, genes including 6-cysteine protein <italic>Pvs230</italic> (PVP01_0415800) and upregulated in late gametocytes <italic>ULG8</italic> (PVP01_1452800) expressed in the female gametocytes, as well as two CPW-WPC family proteins (PVP01_1215900 and PVP01_1320100) expressed in the male gametocytes indicated considerably high nucleotide and haplotype diversity among isolates. Parasite samples expressed in male and female gametocyte genes were observed in separate phylogenetic clusters and likely represented distinct gametocyte clones. Compared to <italic>Pvs</italic>25, <italic>Pvs230</italic> (PVP01_0415800) and a CPW-WPC family protein (PVP01_0904300) showed higher expression in a subset of Ethiopian <italic>P. vivax</italic> samples. Thus, <italic>Pvs230</italic>, <italic>ULG8</italic>, and CPW-WPC family proteins including PVP01_0904300, PVP01_1215900, and PVP01_1320100 could potentially be used as novel biomarkers for detecting both sexes of <italic>P. vivax</italic> gametocytes in low-density infections and estimating transmission reservoirs.</p>