Design of helical, oligomeric HIV-1 fusion inhibitor peptides with potent activity against enfuvirtide-resistant virus

Abstract

Enfuvirtide (ENF), the first approved fusion inhibitor (FI) for HIV, is a 36-aa peptide that acts by binding to the heptad repeat 1 (HR1) region of gp41 and preventing the interaction of the HR1 and HR2 domains, which is required for virus-cell fusion. Treatmentacquired resistance to ENF highlights the need to create FI therapeutics with activity against ENF-resistant viruses and improved durability. Using rational design, we have made a series of oligomeric HR2 peptides with increased helical structure and with exceptionally high HR1/HR2 bundle stability. The engineered peptides are found to be as much as 3,600-fold more active than ENF against viruses that are resistant to the HR2 peptides ENF, T-1249, or T-651. Passaging experiments using one of these peptides could not generate virus with decreased sensitivity, even after >70 days in culture, suggesting superior durability as compared with ENF. In addition, the pharmacokinetic properties of the engineered peptides were improved up to 100-fold. The potent antiviral activity against resistant viruses, the difficulty in generating resistant virus, and the extended half-life in vivo make this class of fusion inhibitor peptide attractive for further development.coiled coil ͉ gp41 HIV-1 ͉ viral entry ͉ drug design

Rigid amphipathic fusion inhibitors, small molecule antiviral compounds against enveloped viruses

“…Current entry inhibitors target interactions between viral proteins and their receptors (8). Investigational compounds also nonspecifically crosslink viral glycoproteins (45).…”

“…Drugs targeting viral glycoproteins or their receptors block the first events in the viral replication cycle and are less constrained by intracellular delivery or metabolism (6,8,9). Unfortunately, these drugs share the limitations of other drugs targeting viral proteins (2,10,11), such as prompt selection for resistance (12,13).…”

Addition of a cholesterol group to an HIV-1 peptide fusion inhibitor dramatically increases its antiviral potency

“…Such is indeed the case for C34, T20 (4), which spans part of the HR2 region and the sequence downstream (Fig. 1), and several other FI-targeting HR1 or HR2, including peptides, proteins, and small molecules (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21).…”

“…Hybrids between C34 and T20 have also been pursued because the membrane-proximal region of gp41, included in T20, is beneficial for half-life (11). Although these peptides form 6-helix bundles with much increased stability with respect to C34, there appears to be a limit to the increase in potency that can be achieved by this route, with antiviral activity reaching a plateau over a wide range of bundle stability (8).…”

“…Because C34 shows essentially no helical structure before folding onto HR1 to form the 6-helix bundle, HR2-derived peptides have been designed with enhanced helical structure in solution, which translates into greater strength of association with the HR1 coiled-coil and greater antiviral potency (8)(9)(10)24). Hybrids between C34 and T20 have also been pursued because the membrane-proximal region of gp41, included in T20, is beneficial for half-life (11).…”