Allelic variants of the Plasmodium falciparum merozoite surface protein-I gene (block 2) in Malaysian isolates

Abstract

Allelic variation of the Plasmodium falciparum MSP-1 gene in Malaysian isolates was studied using a nested-PCR technique directed to block 2, one of the variable regions of the MSP-1 gene. Allele-specific primers were used for the three types of block 2: Kl, MAD20, and RO33. The sizes of the amplification products were in the range of 150 to 200 bp. All three allelic types are present in Malaysian isolates. They exist either on their own or in combination with other allelic types in multiple infections. The more predominant allelic types are Kl and MAD20. Sixty three percent of the in vitro cultured P. falciparum isolates and 46% of the successfully typed isolates from Ranau, Sabah showed co-existence of parasites of both Kl and MAD20 type. The RO33 allelic type was also present in both in vitro cultured isolates and field specimens from Ranau, Sabah.