Covalent Inhibition of HIV Membrane Fusion

Abstract

Peptide inhibitors consisting of sequences from the six helix bundle structure of the fusogenic portion (gp41) of the HIV envelope glycoprotein have been successfully implemented in preventing HIV entry. These peptides block entry by binding to regions of HIV gp41 that are transiently exposed during the fusion stage of viral entry. We have successfully designed and tested peptide analogs composed of chemical spacers and reactive moieties positioned strategically to facilitate the covalent attachment of the peptide to gp41. We have utilized the covalent peptide to show evidence for the trapping of a pre-six helix bundle fusion intermediate by a covalent reaction with a specific anti-HIV-1 peptide. This is the first demonstration in live cells of the trapping of an intermediate conformation of a viral envelope glycoprotein during the fusion process. The permanent specific attachment of the covalent inhibitor is projected to improve the long-term sustainability of peptide entry inhibitor therapy and to serve as an important tool in probing the conformational changes that occur to the envelope protein complex during viral entry.