title: HIV-1 Escape from a Peptidic Anchor Inhibitor through Stabilization of the Envelope Glycoprotein Spike.
abstract: The trimeric HIV-1 envelope glycoprotein spike (Env) mediates viral entry into cells by using a spring-loaded mechanism that allows for the controlled insertion of the Env fusion peptide into the target membrane, followed by membrane fusion. Env is the focus of vaccine research aimed at inducing protective immunity by antibodies as well as efforts to develop drugs that inhibit the viral entry process. The molecular factors contributing to Env stability and decay need to be understood better in order to optimally design vaccines and therapeutics. We generated viruses with resistance to VIR165, a peptidic inhibitor that binds the fusion peptide of the gp41 subunit and prevents its insertion into the target membrane. Interestingly, a number of escape viruses acquired substitutions in the C1 domain of the gp120 subunit (A60E, E64K, and H66R) that rendered these viruses dependent on the inhibitor. These viruses could infect target cells only when VIR165 was present after CD4 binding. Furthermore, the VIR165-dependent viruses were resistant to soluble CD4-induced Env destabilization and decay. These data suggest that VIR165-dependent Env proteins are kinetically trapped in the unliganded state and require the drug to negotiate CD4-induced conformational changes. These studies provide mechanistic insight into the action of the gp41 fusion peptide and its inhibitors and provide new ways to stabilize Env trimer vaccines.
  
  
  OBJECTIVE
  Because of the rapid development of HIV-1 drug resistance, new drug targets need to be explored continuously. The fusion peptide of the envelope glycoprotein can be targeted by anchor inhibitors. Here we describe virus escape from the anchor inhibitor VIR165. Interestingly, some escape viruses became dependent on the inhibitor for cell entry. We show that the identified escape mutations stabilize the ground state of the envelope glycoprotein and should thus be useful in the design of stabilized envelope-based HIV vaccines.
authors.affiliation: Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center of the University of Amsterdam, Amsterdam, the Netherlands.
authors.forename: Dirk
authors.initials: D
authors.lastname: Eggink
authors.affiliation: Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center of the University of Amsterdam, Amsterdam, the Netherlands.
authors.forename: Steven W
authors.initials: SW
authors.lastname: de Taeye
authors.affiliation: Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center of the University of Amsterdam, Amsterdam, the Netherlands.
authors.forename: Ilja
authors.initials: I
authors.lastname: Bontjer
authors.affiliation: Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York, USA.
authors.forename: Per Johan
authors.initials: PJ
authors.lastname: Klasse
authors.affiliation: Pepscan Therapeutics BV, Lelystad, the Netherlands.
authors.forename: Johannes P M
authors.initials: JPM
authors.lastname: Langedijk
authors.affiliation: Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center of the University of Amsterdam, Amsterdam, the Netherlands.
authors.forename: Ben
authors.initials: B
authors.lastname: Berkhout
authors.affiliation: Laboratory of Experimental Virology, Department of Medical Microbiology, Center for Infection and Immunity Amsterdam (CINIMA), Academic Medical Center of the University of Amsterdam, Amsterdam, the Netherlands r.w.sanders@amc.uva.nl.|Department of Microbiology and Immunology, Weill Medical College of Cornell University, New York, New York, USA.
authors.forename: Rogier W
authors.initials: RW
authors.lastname: Sanders
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D019380:Anti-HIV Agents / Q000378:metabolism / Q000494:pharmacology; D001596:Benzylamines; D015704:CD4 Antigens / Q000378:metabolism / Q000494:pharmacology; D000080027:Cyclams; D015752:Genes, env; D015699:HIV Envelope Protein gp120 / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D015700:HIV Envelope Protein gp41 / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D015497:HIV-1 / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D006571:Heterocyclic Compounds / Q000494:pharmacology; D006801:Humans; D008954:Models, Biological; D008958:Models, Molecular; D009154:Mutation; D011487:Protein Conformation; D055550:Protein Stability; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D053586:Virus Internalization / Q000187:drug effects
chemical_list: D019380:Anti-HIV Agents; D001596:Benzylamines; D015704:CD4 Antigens; D000080027:Cyclams; D015699:HIV Envelope Protein gp120; D015700:HIV Envelope Protein gp41; D006571:Heterocyclic Compounds; D011994:Recombinant Proteins; C076613:recombinant soluble CD4; C088327:plerixafor