Genetic changes associated with distinct patterns of HIV type 1 persistence in chronically infected cell lines.

Three persistently infected cell lines (H61, M61, and U61) were established by infection with an HIV-1 isolate (s61) of two T cell lines, H9 and MT-4, and the promonocytic U937-2. In H61, 35% of cells expressed viral antigens yielding low virus titers and a majority of mature particles. M61 showed viral expression in every cell but with the frequent generation of immature particles.