title: Development of resistance to VIR-353 with cross-resistance to the natural HIV-1 entry virus inhibitory peptide (VIRIP).
abstract: OBJECTIVE
  Virus-inhibitory peptide (VIRIP) has been identified as a component of human hemofiltrate that blocks HIV-1 gp41-dependent fusion by interacting with the fusion peptide. A VIRIP analogue (VIR-576) has been shown to be effective in a phase I/II clinical trial. We have evaluated the activity and mechanism of HIV-1 resistance to VIRIP and its analogue, VIR-353.
  
  
  METHODS
  Anti-HIV activity and passage of HIV-1 strains in cell culture were used to generate and identify mutations that confer resistance to VIRIP and VIR-353. Recombinant viruses harboring the most relevant mutations were generated and characterized.
  
  
  RESULTS
  VIRIP and VIR-353 showed anti-HIV-1 activity with EC(50) of 28 and 0.3 μmol/l, respectively, and were active against virus resistant to BMS-155, AMD3100, T20, TAK-779 or nevirapine. Time of addition experiments showed that VIR-353 targets a time/site of action corresponding to gp41-dependent fusion. VIR-353-resistant virus was generated after 450 days in cell culture, suggesting a high genetic barrier for resistance. The VIR-353-resistant virus was cross-resistant to VIRIP but remained sensitive to T20, AMD3100 or zidovudine. Recombination of gp41 into a wild-type backbone partially recovered the resistant phenotype, but both gp120 and gp41 from the resistant virus were necessary to restore resistance to VIRIP or VIR-353. Site-directed mutagenesis confirmed the role of specific mutations and identified a combination of three mutations (A433T/V489I/V570I) as the most relevant to VIRIP resistance.
  
  
  CONCLUSIONS
  VIRIP may interact with a region of gp41 that is essential for fusion but not the fusion peptide. Our results highlight interactions between gp41 and gp120 that may be required during the fusion process.
authors.affiliation: IrsiCaixa, Hospital Universitari Germans Trias i Pujol, Universitat Autònoma de Barcelona, Spain.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Gonzalez
authors.forename: Ester
authors.initials: E
authors.lastname: Ballana
authors.forename: Bonaventura
authors.initials: B
authors.lastname: Clotet
authors.forename: José A
authors.initials: JA
authors.lastname: Esté
mesh_terms: D024882:Drug Resistance, Viral; D015699:HIV Envelope Protein gp120 / Q000187:drug effects / Q000235:genetics; D015700:HIV Envelope Protein gp41 / Q000187:drug effects* / Q000235:genetics; D023581:HIV Fusion Inhibitors / Q000494:pharmacology*; D015497:HIV-1 / Q000187:drug effects / Q000235:genetics; D006801:Humans; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000494:pharmacology*; D053586:Virus Internalization / Q000187:drug effects; D000515:alpha 1-Antitrypsin / Q000494:pharmacology*
chemical_list: D015699:HIV Envelope Protein gp120; D015700:HIV Envelope Protein gp41; D023581:HIV Fusion Inhibitors; D010446:Peptide Fragments; C561794:VIR-353; C519920:VIRIP peptide, human; D000515:alpha 1-Antitrypsin