Low-cytopathic infectious clone of human immunodeficiency virus type I (HIV-I).

Single genotypic variants of HIV-I, contained in a parental cytopathic HIV-I isolate, were isolated by molecular cloning and propagated in susceptible cells. Two such HIV-I clones, designated N1T-E and N1T-A, exhibited similar restriction endonuclease maps but strikingly different biological activities. Infection of T lymphocytes or monocytes by clone N1T-E was characterized by slow kinetics and lack of significant cytopathic effects, but high reverse transcriptase activity levels in culture supernatants of chronically-infected cells. Clone N1T-A, like the parental HIV-I isolate, exhibited fast kinetics of infection in T cells and monocytes and strong cytopathicity in these cells. Full characterization of the low-cytopathic virus in comparison to the structurally similar cytopathic clone may facilitate the elucidation of the molecular basis of HIV cytopathogenicity.