title: Recombinant CD4-selected human immunodeficiency virus type 1 variants with reduced gp120 affinity for CD4 and increased cell fusion capacity.
abstract: Variants of molecularly cloned human immunodeficiency virus type 1 (HIV-1) were analyzed following selection for the ability to replicate after exposure to soluble, recombinant CD4 protein (rCD4). Two variants, 4/1 and 16/2, show 8-fold and 16-fold reduced sensitivity to rCD4 neutralization yet remain as sensitive as the parental wild-type (wt) virus to neutralization by rCD4-immunoglobulin G (IgG) chimeric molecules and to inhibition of cellular infection by anti-CD4 antibody. The 4/1 variant is more cytopathic, with faster cell fusion and replication kinetics than the wt virus. The gp120s derived from the 4/1 and 16/2 variants have 3-fold and 30-fold reduced binding affinities to rCD4, respectively. The 4/1 variant exhibits diminished shedding of virion gp120 induced by rCD4. The binding of and neutralization by V3 loop antibodies and other anti-gp120 antibodies is reduced for 4/1 but not for 16/2. Sequence analysis revealed a codon change at amino acid residue 435 in the C4 region of the gp120 of 16/2. This accounts for its rCD4 insensitivity, since the insertion of this mutation in the wt gp120 yields the same phenotype. The 4/1 variant has a codon change in the V3 region of gp120 (amino acid 311), which accounts for its reduced sensitivity to some neutralizing antibodies but not to rCD4. The ready selection of rCD4-resistant variants has obvious relevance for rCD4-based therapeutic stratagems.
authors.affiliation: Chester Beatty Laboratories, Institute of Cancer Research, London, United Kingdom.
authors.forename: J
authors.initials: J
authors.lastname: McKeating
authors.forename: P
authors.initials: P
authors.lastname: Balfe
authors.forename: P
authors.initials: P
authors.lastname: Clapham
authors.forename: R A
authors.initials: RA
authors.lastname: Weiss
mesh_terms: D000595:Amino Acid Sequence; D015704:CD4 Antigens / Q000235:genetics / Q000378:metabolism*; D002459:Cell Fusion; D003588:Cytopathogenic Effect, Viral; D015483:HIV Antibodies / Q000276:immunology; D015699:HIV Envelope Protein gp120 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D015497:HIV-1 / Q000254:growth & development / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009154:Mutation; D009500:Neutralization Tests; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012995:Solubility; D013329:Structure-Activity Relationship; D014779:Virus Replication
chemical_list: D015704:CD4 Antigens; D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120; D011994:Recombinant Proteins