Diversity of merozoite surface protein-1, 2, 3, 4 and 5(msp-1, 2, 3, 4 and 5) genes among Plasmodium falciparum collected from border areas of Thailand

Abstract

The Plasmodium falciparum merozoite surface proteins (MSPs) hadbeen considered as potential proteinsto develop intoan effective vaccine against malaria infection. Among those MSPs, the considerable proteins included MSP-1, 2, 3, 4 and 5. The variation of the merozoite surface protein (msp) genes, which encoded those MSPs, wouldhave an influenced onthe vaccine development. In Thailand, the msp genes diversity hadbeen studied only in a few areas. The sequence diversity of msp-1, 2, 3, 4 and 5 genes of P. falciparum from 5 Thailand provinces, including Kanchanaburi, Mae Hong Son, Ranong, Ubonratchathani and Trat collected during 2002-2009, was determined in this study. The block 17 of msp-1 gene sequences from 61 isolates and msp-2 gene sequences from 50 isolates had been studied and analyzed their phylogenetic relationship by the PHYLIPSprogram. The results indicated that the sequence of msp-1 block 17 gene in Thailand hadonly 5 limited substitution positions and these produced 5 restricted alleles of encoded MSP-119. The Chi-square testshowedthat the allele distribution patterns in each provincewere statistically different (p<0.001). The msp-2 gene sequence analysis results revealed 2 allele families, 3D7 and FC27 families. The full lengthcomparison of 50 msp-2 sequences (from both families) showed 37 alleles variants most of which weredifferent in their repetitive regions. The phylogenetic analysis of msp-2 gene indicatedthat all sequences from 5 locations were closely related and the members of the same gene family were clustered on the same clade. The DNA sequences of other genes, including msp-3, 4 and 5 genes, could not be obtained by nested-PCR and direct sequencing. More complicated techniques may be needed to complete those gene sequences.