Replicative capacity of human immunodeficiency virus from patients with varying severity of HIV infection.

T-lymphotropic viruses were isolated from 31 patients with different clinical manifestations of human immunodeficiency virus (HIV) infection. Lymphocyte cultures from patients with the acquired immunodeficiency syndrome (AIDS) or pre-AIDS yielded virus rapidly, as indicated by high levels of reverse transcriptase (RT) activity in culture fluids. These viruses were able to establish a persistent infection in several T4-antigen-positive tumour cell-lines. In contrast, lymphocyte cultures from patients with mild or no symptoms yielded virus more slowly and the RT activity was low. Co-cultivation of slow/low-yielding lymphocytes with T4-positive tumour cell-lines showed no or only transient virus production. In 14 out of 23 cases virus could be detected by their fatal cytopathic effects on tumour cells. The relation between severity of illness and in-vitro replication potential of the viruses suggests that in the course of an infection selection may occur for HIV variants that replicate efficiently in T4 cells.