Genetic Characterization of Plasmodium vivax Isolates from Pakistan Using Circumsporozoite Protein (PvCSP) and Merozoite Surface Protein-1 (PvMSP-1) genes as genetic markers
Abstract Background: Plasmodium vivax contributes to over 70% malaria burden in Pakistan, but limited data exists on various aspects including genetic diversity of the parasite as compared to other parts of the world. Since the information about the genetic diversity of P. vivax assists to understand the population dynamics of the parasite, the current study was designed to understand population divergence of Plasmodium vivax in Pakistan using circumsporozoite protein (PvCSP) and merozoite surface protein-1 (PvMSP-1) genes as molecular markers. Methods: PvCSP and PvMSP-1 specific PCR and DNA sequencing were carried out for 150 blood samples collected from Islamabad and Rawalpindi, Pakistan. Genetic diversity and polymorphism was analyzed using ChromasPro, ClustalW, MEGA7, DnaSP v.5 and WebLogo programs. Results: The PCR for PvCSP and PvMSP-1 genes was carried out for 150 P. vivax isolates and resulting the PCR products ranging from 900 to 1100 bp for PvCSP and ~400bp for PvMSP-1 genes respectively. Majority (93%; 141/150) of the P. vivax isolates were of VK210 variant and only 9 isolates were found to be of VK247 variant based on PvCSP gene. Out of the numerous peptide repeat motifs (PRMs) detected, GDRADGQPA (PRM1) and GDRAAGQPA (PRM2) were more extensively dispersed among the P. vivax isolates. Partial sequences (~400bp) at the N-terminal of PvMSP-1 gene depicted high level of diversity.Conclusion: High levels of genetic diversity based on PvCSP and PvMSP-1 genes was observed in the isolated samples from the study area. Parasite typing is essential in predicting pattern of antigenic variations and drug resistance and for effective vaccine designing and development which can further assist in evaluating measures for malaria control at individual and community level. The base-line data presented here warrants future studies to investigate more into the genetic diversity of P. vivax with large sample size from across the country for better understanding of the transmission patterns of vivax malaria.