Résumé
The human immunodeficiency viruses (HIV) are the etiologic agents of AIDS. Two types of HIV exist, essentially derived from independent events of transmission of monkey viruses to man, HIV-1 and HIV-2. These viruses differ with respect to their genetic structure and pathogenesis, the former being responsible for the world pandemic, while the latter is more confined in West Africa. HIV-2 contains the vpx gene, a gene absent in all other primate lentiviruses. Vpx presents a strong homology with Vpr, whose presence is conserved among all primate lentiviruses and, as Vpr, Vpx is incorporated into virion particles and is thus present during the early events of infection of target cells. Nonetheless, Vpx plays a specific and major role during infection of cells of myeloid origin, that are key cells in the virus-induced pathogenesis. In these cells, Vpx seems to counteract an antiviral restriction mechanism, and its presence results in a strong acccumulation of viral DNA. The molecular mecanism through which Vpx acts are not understood today, but several lines of evidence suggest that Vpx may act through the recruitment of an ubiquitin-ligase complex. Here, we review the historical and latest developments on the Vpx protein.