       Document 0653
 DOCN  M9640653
 TI    The molecular target of bicyclams, potent inhibitors of human
       immunodeficiency virus replication.
 DT    9604
 AU    de Vreese K; Kofler-Mongold V; Leutgeb C; Weber V; Vermeire K; Schacht
       S; Anne J; de Clercq E; Datema R; Werner G; Rega Institute for Medical
       Research, Katholieke Universiteit; Leuven, Belgium.
 SO    J Virol. 1996 Feb;70(2):689-96. Unique Identifier : AIDSLINE
       MED/96135175
 AB    Bicyclams are a novel class of antiviral compounds which act as potent
       and selective inhibitors of the replication of human immunodeficiency
       virus type 1 (HIV-1) and HIV-2. They block an early step in the viral
       life cycle following adsorption to the CD4 receptor and preceding
       reverse transcription. To identify the molecular target of these
       compounds, we genetically analyzed variants of the HIV-1 molecular clone
       NL4-3, which developed resistance against two structurally related
       bicyclams, JM2763 and the more potent SID791. The resistant strains were
       obtained after long-term passaging in MT-4 cells in the presence of
       progressively increasing compound concentrations. Recombinants between
       selected genes of the resistant strains and the parental NL4-3 provirus
       were generated by adapting the marker rescue technique to MT-4 cells.
       The bicyclam-resistant phenotype was rescued by transferring the
       envelope gp120 gene of bicyclam-resistant virus into the NL4-3 parental
       genetic background. In the gp120 genes of the resistant strains, we
       identified several mutations leading to amino acid substitutions in the
       V3 loop. Furthermore, two substitutions of highly conserved amino acids
       in close proximity to the disulfide bridges of the V3 and V4 loops were
       found in both SID791- and JM2763-resistant strains. Additional mutations
       in regions encoding V3, C4, V5, and C5 were present in SID791-resistant
       viruses. Recombination experiments with overlapping parts of the
       envelope gene indicated that most, if not all, of the mutations were
       necessary to develop the fully SID791 resistant phenotype. The mutations
       in the C-terminal part of gp120 downstream of the V3 loop sequence
       conferred partial resistance to JM2763 but did not significantly
       decrease susceptibility to SID791. The genetic data and the biological
       properties of the resistant viruses point to inhibition of entry and
       fusion as the mode of action of the HIV-inhibitory bicyclams. A possible
       mechanism of binding of bicyclams to gp120 leading to inhibition of
       unfolding of gp120 and its shedding from the gp41 fusion domain is
       discussed.
 DE    Amino Acid Sequence  Antiviral Agents/CHEMISTRY/*PHARMACOLOGY  Base
       Sequence  Binding Sites  Cell Line  Drug Resistance, Microbial/GENETICS
       Genes, env  Heterocyclic Compounds/CHEMISTRY/*PHARMACOLOGY  Human  HIV
       Envelope Protein gp120/DRUG EFFECTS/GENETICS  HIV-1/*DRUG
       EFFECTS/ISOLATION & PURIF  Molecular Sequence Data  Mutation  Peptide
       Fragments/DRUG EFFECTS/GENETICS  Structure-Activity Relationship
       Support, Non-U.S. Gov't  JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).

