Nef (Negative Regulatory Factor) is a protein expressed by primate lentiviruses. These include human immunodeficiency viruses (HIV-1 and HIV-2) and simian immunodeficiency virus (SIV). Nef is one of many pathogen-expressed proteins, known as virulence factors, which function to manipulate the host's cellular machinery and thus allow infection, survival or replication of the pathogen. Nef stands for Negative Factor. Alternative Names: HIV 1 nef, 3'ORF protein, Negative factor protein, HIV-1 Nef protein, p27 protein, HIV-1 nef protein, HIV1 nef, C terminal core protein protein, HIV-1 nef, Nef protein, ABIN1 protein, VAN protein , ABIN protein, F protein protein, HIV 1 nef protein