GENOTYPING OF HUMAN T-CELL LYMPHOTROPIC VIRUS TYPE-I USING AUSTRALO-MELANESIAN TOPOTYPE-SPECIFIC OLIGONUCLEOTIDE PRIMER-BASED POLYMERASE CHAIN-REACTION - INSIGHTS INTO VIRAL EVOLUTION AND DISSEMINATION

Sequence variants of human T cell lymphotropic virus type I (HTLV-I), genetically distinct from cosmopolitan strains of HTLV-I from Japan, t he Americas, the Caribbean, and Africa, have been discovered among Mel anesians in Papua New Guinea and the Solomon Islands and among Austral ian aboriginals, By using oligonucleotide primer pairs derived from se quences unique to the gp46- and gp21-encoding regions of the env gene of the Melanesian HTLV-I variants, HTLV-I strains from widely separate d geographic regions could be grouped into either of two major geograp hic-specific genotypes or topotypes: Australo-Melanesian and cosmopoli tan. These primers did not permit amplification of the corresponding e nv gene regions in strains of simian T cell lymphotropic virus type I from Asia and Africa. Phylogenetic analysis also supported two distinc t lineages, consistent with evolution of HTLV-I in Australia and Melan esia independent from that in other parts of the world.