Protein Nef Extracellular Nef protein targets CD4(+) T-lymphocytes for apoptosis by interacting with CXCR4 surface receptors (By similarity). nef In infected CD4(+) T-lymphocytes, downregulates cell surface expression of CD4, CD28, CD3, and MHC-I or MHC-II molecules (By similarity). Interferes with TCR signaling from the cell membrane. Interacts with CD247/TCRZ (TCR zeta chain) and exert potent down- regulation of cell surface TCR/CD3 complexes. Factor of infectivity and pathogenicity, required for optimal virus replication. Alters numerous pathways of T- lymphocytes function and downregulates immunity surface molecules in order to evade host defense and increase viral infectivity. Alters the functionality of other immunity cells, like dendritic cells, monocytes/macrophages and NK cells. One of the earliest and most abundantly expressed viral proteins (By similarity). Negative factor NEF_HV2D1 3'ORF MGASGSKKRSEHSQGLRERLLRARGGGYVKQRNASGGESSQSQEGSGREQKSPSCEGQQYQQGEFMNTPWRTPAAIGQKNSYKQQNMDDVDSDDDDLVGVPVMPRVPLREMTYKLAIDMSHFIKEKGGLEGIFYSRERHRILDLFLEKEEGIIPDWQNYTHGPGTRYPMYFGWLWKLVPVDISQEAEEVETNCLVHPAQTSRYDDEHGETLVWRFDPMLAYSYKAFILHPEEFGHKSGLPEKEWKAKLKARGIPYSE Plays a role in optimizing the host cell environment for viral replication without causing cell death by apoptosis. Protects the infected cells from apoptosis in order to keep them alive until the next virus generation is ready to strike (By similarity). 257