Circumsporozoite protein (CSP) genetic diversity in Indian Plasmodium vivax

India is one of the Plasmodium vivax endemic countries and contributes the highest number of malaria cases worldwide. P. vivax CSP (PvCSP) is one of the most extensively studied antigen and is considered to be a leading malaria vaccine candidate gene. VK210 and VK247 are the two variants described in the central repeat region of P. vivax CSP gene. VK210 (98%) is found to be more prevalent as compared to VK247 (2%) in Indian context. It was noticed that different geographical regions show diversity in nucleotides as well as in haplotype with respect to PvCSP gene of Indian isolates. As natural selection always plays an important role in shaping genomic diversity in Indian P. vivax, the central repeat region of PvCSP gene of all the five-populations found to be under strong purifying selection. In this region, a number of synonymous mutations were found to be higher in number as compared to non-synonymous mutation, which clearly indicated that PvCSP gene is involved in invasion of hepatocytes in the host body and the parasite can't afford non-synonymous changes in this region. The present study helps us to understand the nature of P. vivax population in India, and also that might be helpful in planning the development of PvCSP-based vaccine in India.