Genetic diversity analysis of PvCSP and its application in tracking of Plasmodium vivax

Abstract

BackgroundPlasmodium vivax remains a potential cause of morbidity and mortality for people living where it is endemic. Understanding the regional genetic diversity of P. vivax is valuable for studying population dynamics and tracing the origins of parasites. The Plasmodium vivax circumsporozoite gene (PvCSP) is highly polymorphic and has been used previously as a marker in P. vivax population studies. The aim of this study is to investigate the genetic diversity of the PvCSP, to provide more genetic polymorphism data for further studies on P. vivax population structure, and tracking of the origin of clinical cases. MethodsNested PCR and DNA sequencing of the PvCSP were performed to obtain nucleotide sequences of P. vivax isolates collected from Zhejiang province, China, between 2006 and 2014. To investigate the genetic diversity of PvCSP, the nucleotide sequences and amino acid sequences of the PvCSP were analyzed using DNAstar, Mega software and the phylogenetic tree constructed. The relatedness between the polymorphism and infection source were also analyzed using the SPSS software. ResultsThe 66 P. vivax isolates collected from Zhejiang province were either indigenous cases or cases imported from different regions of the world. All 66 P. vivax isolates belonged to the VK210 variant. Fourteen different Peptide Repeat Motifs (PRMs) were detected in the Central Repeat Region (CRR) of PvCSP, among which, two PRMs of GDRADGQPA and GDRAAGQPA were widely distributed in all isolates. Several polymorphic characteristics of the VK210 variant were observed, including the insertion sequence of 12 peptides, the frequency of the GGNA repeat, the frequency of the PRMs repeat in CRR, and the frequency of the PRM of GNGAGGQAA repeat, which were indicative for tracking the parasite. ConclusionThis study presents abundant genetic diversity in the PvCSP marker among P. vivax strains around the world. The genetic data are valuable to expand the polymorphism information on P. vivax, which could be helpful for further study on population dynamics and tracking the origin of P. vivax.