Comparison between strains of human T lymphotropic virus type I isolated from inhabitants of the Solomon Islands and Papua New Guinea.

Strains of human T lymphotropic virus type I (HTLV-I) isolated from T cell lines (SI-1, SI-3, and SI-5) from three individuals in separate regions of the Solomon Islands were compared with a variant (PNG-1) isolated from a healthy person in Papua New Guinea and a prototype strain from Japan (MT-2). The SI-1, SI-3, and SI-5 cell lines were predominantly CD8+. Expression of gag- and env-encoded virus-specific proteins was detected in SI-1, SI-3, and SI-5 and in MT-2 cells by immunofluorescence and Western immunoblot; gag proteins p19 and p24 were absent in PNG-1 cells. HTLV-1 gag and pol gene sequences were detected in DNA extracted from SI-1, SI-3, and SI-5 cells by polymerase chain reaction; env sequences were not found in SI-5 cells. Genomic Southern analysis of PstI digests of SI-1, SI-3, and SI-5 DNA exhibited the three moderate-sized fragments typical of prototype HTLV-I. By contrast, PstI digests of PNG-1 DNA yielded two larger fragments.