[From HIV infection to AIDS].

HIV is the causative agent of AIDS. It is a retrovirus of the Lentiviridae family whose known biological properties may account for the diversity of the pathology it causes. HIV displays selective tropism for CD4+ lymphocytes and for cells of the macrophage lineage, the cellular receptor involving the CD4 molecule itself. Its latent integration in its targets' genome and its restricted replication explain the observed frequency of asymptomatic carriers and of prolonged incubation periods. Its strong cytopathic effect and the direct activity of some of its soluble proteins is certainly the cause of the immune abnormalities that may follow infection. Altogether, most of the clinical disorders noted after HIV infection appear to result from the interaction between these viral properties and host-dependent factors such as a particular genetic background or immunologic "terrain".