Transmission of human T-cell leukemia virus type I from a patient with HTLV-I associated myelopathy/tropical spastic paraparesis and an asymptomatic carrier to rabbits.

Rabbits were infected successfully with two strains of human T-cell leukemia virus type I (HTLV-I), one isolated from a Colombian patient with HTLV-I associated myelopathy/tropical spastic paraparesis (HAM/TSP) and the other from an asymptomatic carrier. HTLV-I was repeatedly demonstrated in peripheral blood mononuclear cells (PBMNC) of infected rabbits, and the rabbits had elevated antibodies against the various structural proteins of HTLV-I. Four rabbits inoculated with HTLV-I-infected autologous lymphoid cells intravenously (i.v.) and intracerebrally (i.c.) had virus present in their PBMNC for more than 40 weeks, while those that were inoculated either with HTLV-I-infected human lymphoid cells or with autologous rabbit lymphoid cells intraperitoneally (i.p.) had episodes during which virus was not recovered from their PBMNC. The one rabbit inoculated i.p. developed antibodies to viral envelope glycoproteins earlier than did those inoculated i.v. and i.c. Rabbit lymphoid cell lines persistently infected with HTLV-I were established by cocultivating the rabbit PBMNC with HTLV-I-infected human lymphoid cells that had been irradiated or by inoculation with cell-free supernatant fluids of HTLV-I infected non-irradiated lymphoid cell cultures. HTLV-I-infected rabbit cell lines were of T-cell origin and expressed HTLV-I antigens by immunofluorescence. Electron microscopy revealed type-C retrovirus particles.