Variable number of tandem repeats of 9 Plasmodium vivax genes among Southeast Asian isolates

- Nine TR sequences of P. vivax that were suitable for genotyping purposes (i.e., a VARscore in the SEVR analysis of 1-3) were observed from 230 ORFs genes.
- These nine VNTRs are highly polymorphic in 4 SEA countries (China, South Korea, Thailand, and Myanmar) with different malaria endemicity.
- Similar values of HE were observed in the Chinese and ROK isolates, however, the Thai and Myanmar isolates displayed higher diversity.

The variable number of tandem repeats (VNTRs) provides valuable information about both the functional and evolutionary aspects of genetic diversity. Comparative analysis of 3 Plasmodium falciparum genomes has shown that more than 9% of its open reading frames (ORFs) harbor VNTRs. Although microsatellites and VNTR genes of P. vivax were reported, the VNTR polymorphism of genes has not been examined widely. In this study, 230 P. vivax genes were analyzed for VNTRs by SERV, and 33 kinds of TR deletions or insertions from 29 P. vivax genes (12.6%) were found. Of these, 9 VNTR fragments from 8 P. vivax genes were used for PCR amplification and sequence analysis to examine the genetic diversity among 134 isolates from four Southeast Asian countries (China, Republic of Korea, Thailand, and Myanmar) with different malaria endemicity. We confirmed the existence of extensive polymorphism of VNTR fragments in field isolates. This detection provides several suitable markers for analysis of the molecular epidemiology of P. vivax field isolates.

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