Genetic polymorphisms of merozoite surface protein-3α in Plasmodium vivax isolates from Pakistan.

The merozoite surface protein-3α of Plasmodium vivax (PvMSP-3α) is a promising vaccine candidate attributed to its important biological role and immunogenicity. The heterogeneity of pvmsp-3α in P. vivax populations underscore the importance of understanding the genetic diversity of this vaccine candidate in clinical isolates. In this study, we analyzed the genetic polymorphisms and natural selection of the pvmsp-3α in Pakistani P. vivax isolates. Blood samples collected from P. vivax-infected patients in Khyber Pakhtunkhwa province, Pakistan, between 2020 and 2021 were analyzed. The pvmsp-3α was amplified in 129 Pakistani P. vivax isolates, cloned, and sequenced. The genetic diversity and natural selection of pvmsp-3α in Pakistan and other geographical areas were comparatively analyzed. Pakistani pvmsp-3α exhibited genetic diversity. Size polymorphisms in block I and amino acid changes and recombination events in block II were the main factors generating genetic diversity in Pakistani pvmsp-3α. Comparative analysis of Pakistani pvmsp-3α with pvmsp-3α populations from other geographically different countries revealed that Pakistani pvmsp-3α showed the highest genetic diversity. Genetic differentiations and distinct natural selection trends were identified between and among Pakistani and other pvmsp-3α populations. Haplotype network analysis indicated substantial genetic heterogeneity in the gene in global P. vivax populations. This study expands the knowledge of genetic polymorphisms and evolutionary trends in the Pakistani pvmsp-3α population, providing valuable insight for understanding the genetic nature of the gene in global P. vivax populations.