JLE

Virologie

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Functions of the Vif protein of human immunodeficiency virus type 1 Volume 3, issue 5, Septembre - Octobre 1999

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Lentiviruses differ from other classes of retroviruses by the presence of regulatory genes in their genome. These genes, which are additional to the structural genes gag, pro-pol and env, are subdivided into two groups : the essential genes tat and rev and the accessory or auxiliary genes vif, vpr, vpx (HIV2 and related SIV), vpu and nef. While these last genes were denominated accessory genes, the study of the viral replication of lentiviruses within their natural host or experimental animals revealed that these genes code for proteins essential for the propagation of infection in vivo and for the pathogenesis. Indeed, they optimize the viral replication and favor the progression of infection in vivo. The Vif (viral infectivity factor) protein of HIV1 increases strongly the infectivity of virions in restrictive T lymphocytes and macrophages. Nevertheless, the biochemical activities of the Vif protein of HIV1 are still poorly understood. Recent data revealed : i) that Vif interacts with Gag and the viral protease present in the virion complexes assembling at the end of the viral cycle, ii) that cellular factors inhibiting the infectivity of viral particles are present in restrictive T cells and are neutralized by the Vif protein. The elaboration of new anti-retroviral therapeutic protocols may emerge following these new discoveries.