HIV-1 negative factor protein (Nef)

The HIV-1 negative factor (Nef) protein is a 27–35 kDa myristoylated accessory protein encoded by primate lentiviruses such as HIV-1, HIV-2, and SIV[1][2]. Nef is essential for efficient viral pathogenesis but is not required for viral replication in vitro. It functions mainly to enhance HIV replication and infectivity, as well as to mediate immune evasion by altering the trafficking and expression of key cell-surface molecules, including CD4 and MHC class I, on infected cells[1][2][3]. Nef acts through multiple mechanisms: (1) it interacts with host cell vesicular trafficking and endocytic machinery (AP-1, AP-2, and βCOP1), (2) downregulates cell-surface receptors (notably CD4, to prevent superinfection, and MHC-I, to diminish immune visibility), and (3) modulates cellular signaling pathways by binding to SH3 domains of Src family kinases, which may alter T cell receptor signaling and promote a cellular environment conducive to HIV replication and immune escape[1][2][3][4]. Nef is considered a high-value therapeutic target for novel antiretroviral agents or immune therapies due to its crucial role in viral pathogenicity and immune modulation. There is significant structural and functional conservation among Nef proteins from different HIV and SIV strains, but functional differences exist, especially in motifs mediating endocytosis and immune receptor modulation[2].

Other names

HIV-1 NefHIV-2 Nefnegative factornef protein

Inhibitors can block binding between Nef and host cell kinases (e.g., Src family kinases), adaptor proteins (AP-1/AP-2), or other trafficking/signaling molecules to interfere with Nef-mediated immune evasion[1][3][4].