Novel HIV fusion-inhibitory lipopeptides exhibit dramatically improved activity against resistant mutants.

LP-98 is a potent HIV fusion-inhibitory lipopeptide but displays reduced activity against resistant mutants. In this study, we rationally designed a group of new lipopeptides by adding different lengths of gp41 pocket-binding sequence into the N-terminus of LP-98. It was found that a single pocket-inserting residue Ile124 critically determined the anti-HIV activity, whereas incorporation of additional pocket-inserting residues Trp120 and Trp117 generated lipopeptides with greatly reduced activity. As indicated by LP-101 and LP-108, while Ile124-modified lipopeptides maintained or improved the inhibitory activity of LP-98 against divergent HIV and SIV isolates, they had dramatically increased potencies on the resistant mutants. In both the HIV-infected humanized mice and SIV-infected rhesus macaques, LP-101 efficiently suppressed viral replication below detection limits. Mechanically, Ile124-modified lipopeptides exhibited greatly enhanced binding affinity with a target-mimic peptide N44. We determined the crystal structure of LP-101 bound to N44, revealing its N-terminal residues penetrating deeper into the gp41 pocket, forming enhanced interactions with the target site. Molecular dynamics simulations also revealed its flexible N-terminus enables adaptive binding to the wild-type and resistant mutants, with improved binding free energies. Therefore, our data inform the structure-activity relationship of this class of HIV fusion inhibitors and offer new candidates for drug development.