title: Analysis of the V3 loop in neutralization-resistant human immunodeficiency virus type 1 variants by direct solid-phase DNA sequencing.
abstract: To study the molecular basis for the emergence of human immunodeficiency virus type 1 (HIV-1) variants with reduced sensitivity to neutralization by autologous sera, the DNA sequence of the envelope V3 loop was determined in HIV-1 isolates derived from four patients with primary HIV-1 infection and sequentially thereafter. The gene fragment encoding the V3 loop of gp120 was amplified by a nested polymerase chain reaction (PCR) and subsequently sequenced by a novel solid phase DNA sequencing approach allowing direct sequencing of the viral genome without the need for previous cloning. The results show that all patients have HIV-1 with unique primary sequence of the V3 loop and antibodies to this structure are produced at seroconversion. The structural analysis also demonstrates that the mechanism for virus escape from neutralization in vivo is complex. Thus, in one patient the emergence of neutralization-resistant viruses coincided with the introduction of several amino acid changes in the V3 loop, while in two other patients the V3 loop remained completely unchanged. These findings suggest that an understanding of the interaction between the humoral immune response and HIV-1 may require detailed structural studies of the entire envelope.
authors.affiliation: Department of Biochemistry and Biotechnology, Royal Institute of Technology, Stockholm, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Wahlberg
authors.forename: J
authors.initials: J
authors.lastname: Albert
authors.forename: J
authors.initials: J
authors.lastname: Lundeberg
authors.forename: A
authors.initials: A
authors.lastname: Von Gegerfelt
authors.forename: K
authors.initials: K
authors.lastname: Broliden
authors.forename: G
authors.initials: G
authors.lastname: Utter
authors.forename: E M
authors.initials: EM
authors.lastname: Fenyö
authors.forename: M
authors.initials: M
authors.lastname: Uhlén
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D015483:HIV Antibodies / Q000276:immunology; D015699:HIV Envelope Protein gp120 / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D015658:HIV Infections / Q000382:microbiology*; D015497:HIV-1 / Q000235:genetics / Q000276:immunology*; D006801:Humans; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D016133:Polymerase Chain Reaction
chemical_list: D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120; C059762:HIV envelope protein gp120 (305-321); D010446:Peptide Fragments