Extensive heterozygosity in flanking microsatellites of Plasmodium falciparum Na⁺/H⁺ exchanger (pfnhe-1) gene among Indian isolates

Abstract

Plasmodium falciparum Na⁺/H⁺ exchanger-1 (pfnhe-1) gene has been proposed to be a possible marker for quinine resistance. Here, we describe the sequence analysis of the flanking microsatellites of the pfnhe-1 gene among 108 Indian P.falciparum isolates. Among the parasite population, a high degree of polymorphism was observed at all the 10 microsatellite loci within ±40 kb region of the pfnhe-1 gene where the number of alleles varied from 2 to 16 with a high expected heterozygosity ranging from 0.43 to 0.91 at these loci. Also, higher levels of heterozygosity have been observed in P.falciparum isolates collected from both low and high transmission and drug resistant areas. Furthermore, there was no association between QN resistance associated DNNND repeats in PFNHE-1 and the flanking microsatellite haplotypes. In conclusion, the observed high level of microsatellite polymorphism and absence of selective sweep in the flanking ±40 kb region of the pfnhe-1 gene could be an indication that there is no strong selection pressure on this target gene.