ALLELIC VARIANTS OF THE PLASMODIUM-FALCIPARUM MEROZOITE SURFACE-ANTIGEN-2 (MSA-2) IN A GEOGRAPHICALLY RESTRICTED AREA OF IRIAN-JAYA

Blood samples were collected from 12 residents of 4 villages in the Ok sibil area of Irian Jaya. Eleven patients were positive for Plasmodium falciparum infection as evidenced by successful amplification of the MSA-2 gene by the polymerase chain reaction. Two patients showed evide nce of infection by 2 strains of Plasmodium falciparum. All MSA-2 gene s were completely sequenced and all could be assigned to one of the tw o major allelic families of MSA-2, however all MSA-2 gene sequences di ffered from previously described alleles. Five new allelic forms were identified, one of which was present in 8 of the 11 patients. Within s mall natural populations of P. falciparum, it appears that variation i n MSA-2 approximates that seen world-wide. All samples were also analy sed by hybridisation of amplified DNA to family specific probes and al l samples hybridised to known probes. Our results demonstrate that the re is a degree of microheterogeneity of MSA-2 that is undetectable by hybridisation studies alone.