title: Human immunodeficiency virus type 1 infection of SK-N-MC cells: domains of gp120 involved in entry into a CD4-negative, galactosyl ceramide/3' sulfo-galactosyl ceramide-positive cell line.
abstract: The primary receptor for human immunodeficiency virus (HIV) is the CD4 molecule; however, in vitro evidence suggests that a neutral glycolipid, galactosyl ceramide (GalCer) or a derivative molecule, 3' sulfogalactosyl ceramide (GalS), may serve as an alternative receptor for HIV type 1 (HIV-1) in cells of neural and colonic origin. Biochemical studies have demonstrated that recombinant gp120 envelope protein binds to GalCer/GalS in both solid-phase enzyme-linked immunosorbent assay and high-performance thin-layer chromatography overlays. We have used the SK-N-MC cell line, a CD4-negative, GalCer/GalS-positive cell line previously characterized as susceptible to HIV-1 infection, to identify virus isolates with either a positive infection phenotype, HIVHxB2, or a negative infection phenotype, HIV-1(89.6). Using a solid-phase virus binding assay, we determined the level of restriction in HIV-1(89.6) infection to be at the level of virus-glycolipid binding. Furthermore, using HIV-1HxB2-HIV-1(89.6) chimeras, we have identified a 193-amino-acid fragment from the envelope region of HIV-1HxB2 containing the V3, V4, and V5 regions which confers a positive infection phenotype on the HIV-1(89.6) background. Recombinant viruses which separate this 193-amino-acid fragment into two distinct chimeras are each able to confer a positive infection phenotype on the background of HIV89.6, suggesting that a stable GalCer/GalS-envelope interaction is dependent on the conformation of the envelope protein in the context of the viral membrane. Alternatively, the GalCer/GalS-gp120 bond may involve multiple sites on the oligomeric envelope protein.
mesh_terms: D015703:Antigens, CD / Q000235:genetics* / Q000502:physiology; D001483:Base Sequence; D001665:Binding Sites; D015704:CD4 Antigens / Q000235:genetics* / Q000502:physiology; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D017931:DNA Primers; D004279:DNA, Viral / Q000032:analysis / Q000302:isolation & purification; D004797:Enzyme-Linked Immunosorbent Assay; D005699:Galactosylceramides / Q000032:analysis / Q000502:physiology*; D015699:HIV Envelope Protein gp120 / Q000378:metabolism*; D015497:HIV-1 / Q000235:genetics / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D009447:Neuroblastoma; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011991:Receptors, Virus / Q000032:analysis / Q000502:physiology*; D013045:Species Specificity; D013433:Sulfoglycosphingolipids; D014407:Tumor Cells, Cultured
chemical_list: D015703:Antigens, CD; D015704:CD4 Antigens; D017931:DNA Primers; D004279:DNA, Viral; D005699:Galactosylceramides; D015699:HIV Envelope Protein gp120; D011991:Receptors, Virus; D013433:Sulfoglycosphingolipids; C084124:I(3)SO3-galactosylceramide