title: Deletion of N-terminal myristoylation site of HIV Nef abrogates both MHC-1 and CD4 down-regulation.
abstract: HIV-1 Nef is a desirable vaccine component because it is expressed early and abundantly during HIV infection, and contains many CTL, T-helper cell, and B-cell epitopes. Nef, however, down-regulates MHC-1 and CD4 cell surface expression, contributing to viral escape from host immunity. To prevent Nef from down-regulating both MHC-1 and CD4 while preserving most CTL epitopes, a panel of Nef mutants was constructed and assessed. Some mutants, as expected, modulated either MHC-1 or CD4 expression. Others prevented down-regulation of both proteins but sacrificed numerous immunogenic epitopes. Deletion of 19 N-terminal amino acids including the myristoylation signal from Nef completely abrogated both MHC-1 and CD4 down-regulation while preserving most CTL, T-helper and B-cell epitopes. Our results demonstrate that the myristoylation signal in the Nef protein is critical for Nef-mediated endocytosis of both MHC-1 and CD4. Non-myristoylated Nef containing a full complement of CTL epitopes has greater potential as a vaccine component than wild-type Nef.
authors.affiliation: Basic Research Laboratory, National Cancer Institute, National Institutes of Health, 41 Libary Drive, Building 41 Room d804, Bethesda, MD 20892-5055, USA. guroffm@exchange.nih.gov
authors.forename: B
authors.initials: B
authors.lastname: Peng
authors.forename: M
authors.initials: M
authors.lastname: Robert-Guroff
mesh_terms: D016915:AIDS Vaccines; D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics / Q000276:immunology; D015704:CD4 Antigens / Q000096:biosynthesis* / Q000235:genetics; D002460:Cell Line; D004252:DNA Mutational Analysis / Q000379:methods; D004279:DNA, Viral / Q000235:genetics; D015536:Down-Regulation / Q000235:genetics* / Q000276:immunology; D015693:Gene Products, nef / Q000235:genetics* / Q000378:metabolism; D015497:HIV-1 / Q000378:metabolism*; D015395:Histocompatibility Antigens Class I / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed / Q000235:genetics; D019814:Myristic Acid / Q000378:metabolism*; D010446:Peptide Fragments / Q000235:genetics* / Q000378:metabolism; D017384:Sequence Deletion / Q000235:genetics / Q000276:immunology*; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D054311:nef Gene Products, Human Immunodeficiency Virus
chemical_list: D016915:AIDS Vaccines; D015704:CD4 Antigens; D004279:DNA, Viral; D015693:Gene Products, nef; D015395:Histocompatibility Antigens Class I; D010446:Peptide Fragments; D054311:nef Gene Products, Human Immunodeficiency Virus; D019814:Myristic Acid