Retroviral Vif (Viral infectivity) protein (IPR000475)

Short name: Viral_infect

Overlapping homologous superfamilies


Family relationships



The virion infectivity factor (vif) of Human immunodeficiency virus 1 (HIV-1) affects the infectivity of virus particles [PMID: 3497453] to T lymphocytes and macrophages (in some cases increasing the infectivity of HIV-1 particles by 100- to 1000-fold), but has no direct effect on transcription, translation or virus release. Vif antibodies are found in the sera of patients at all levels of HIV-1 infection, indicating that vif is expressed in natural infections in vivo. Other lentiviruses, including Simian immunodeficiency virus (SIV-cpz), Visna/Maedi virus, and Feline immunodeficiency virus (FIV), have vif open reading frames, suggesting vif plays an essential role during natural infections [PMID: 1357189]. The expression of vif in BHK-21 cells has been shown to be linked to a modification of the C terminus of gp41env, which modification is inhibited by trans-epoxysuccinyl-L-leucylamido-(4-guanidio)butane (E64), a specific inhibitor of cysteine proteases [PMID: 1995946]. Coupled with sequence analysis and the effects of point mutations in vif, it has been suggested that vif could be a cysteine protease. Virions produced in the absence of Vif have abnormal core morphology and those produced in primary T cells carry immature core proteins and low levels of mature capsid [PMID: 14618252].

GO terms

Biological Process

GO:0019058 viral life cycle

Molecular Function

No terms assigned in this category.

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.