Genetic diversity of Merozoite surface protein 1-42 (MSP1-42) fragment of Plasmodium vivax from Indonesian isolates: Rationale implementation of candidate MSP1 vaccine.

Morbidity and mortality related to malaria in Indonesia are attributed to both Plasmodium falciparum and P. vivax parasites. In addition to vaccines for P. falciparum, vaccines against P. vivax are urgently needed for the prevention of the disease. An extensively studied antigen is the carboxyl-terminus of the 42 kDa region of P. vivax merozoite surface protein-1 (PvMSP1-42). The design of a vaccine based on this antigen requires an understanding of the extent of polymorphism. However, there is no information on the genetic diversity of the antigen in Indonesia. This study aimed to profile the diversity of PvMSP1-42 and its two subdomains (PvMSP1-33 and PvMSP1-19) among Indonesian P. vivax isolates. A total of 52 P. vivax-infected blood samples were collected from patients in two different endemic areas in Indonesia: Banjarmasin (Kalimantan) and Sumba Timur (Nusa Tenggara Timur). The polymorphic characteristics and natural selection of PvMSP1-42 were analyzed using the DnaSP, MEGA, and Structure software. Thirty distinct haplotypes of PvMSP1-42 were identified. They displayed amino acid changes compared to the reference PVP01 sequence. Most of the mutations were concentrated in the 33 kDa fragment. PvMSP1-42 of the Indonesian isolates appeared to be under positive selection. Recombination may also play a role in the resulting genetic diversity of PvMSP1. In conclusion, PvMSP1-42 of Indonesian isolates displayed allelic polymorphisms caused by mutation, recombination, and positive selection. These results will aid the understanding of the P. vivax population in Indonesia and to develop a PvMSP1 based vaccine against P. vivax.