Effect of cyclosporin A on the replication cycle of human immunodeficiency virus type 1 derived from H9 and Molt-4 producer cells

The effect of cyclosporin A (CsA) on the replication of human immunodeficiency virus type 1 (HIV-1) was studied. CsA treatment inhibited virus production in chronically infected H9 and Molt-4 cells. CsA treatment of HeLaCD4-LTR/-gal cells or extracellular viruses also inhibited infection (IC₅₀ 1 µg/ml). The intracellular CsA-binding molecule cyclophilin A was detected in HIV-1 derived from chronically infected H9 cells, but it was present at a substantially lower level in HIV-1 derived from chronically infected Molt-4 cells. The low level of cyclophilin A in viral particles derived from Molt-4 cells correlated well with their substantially lower infectivity as assayed on HeLaCD4-LTR/-gal cells. CsA treatment of infected cells showed a dose-dependent reduction of cyclophilin A incorporation into virions; the amount of cyclophilin A incorporation was found to be dependent on the producer cell type.