Adding an Artificial Tail—Anchor to a Peptide-Based HIV-1 Fusion Inhibitor for Improvement of Its Potency and Resistance Profile

Abstract

Peptides derived from the C-terminal heptad repeat (CHR) of human immunodeficiency virus type 1 (HIV-1) envelope protein transmembrane subunit gp41, such as T20 (enfuvirtide), can bind to the N-terminal heptad repeat (NHR) of gp41 and block six-helix bundle (6-HB) formation, thus inhibiting HIV-1 fusion with the target cell. However, clinical application of T20 is limited because of its low potency and genetic barrier to resistance. HP23, the shortest CHR peptide, exhibits better anti-HIV-1 activity than T20, but the HIV-1 strains with E49K mutations in gp41 will become resistant to it. Here, we modified HP23 by extending its C-terminal sequence using six amino acid residues (E6) and adding IDL (Ile-Asp-Leu) to the C-terminus of E6, which is expected to bind to the shallow pocket in the gp41 NHR N-terminal region. The newly designed peptide, designated HP23-E6-IDL, was about 2- to 16-fold more potent than HP23 against a broad spectrum of HIV-1 strains and more than 12-fold more effective against HIV-1 mutants resistant to HP23. These findings suggest that addition of an anchor–tail to the C-terminus of a CHR peptide will allow binding with the pocket in the gp41 NHR that may increase the peptide’s antiviral efficacy and its genetic barrier to resistance.

A Peptide-Based HIV-1 Fusion Inhibitor with Two Tail-Anchors and Palmitic Acid Exhibits Substantially Improved In Vitro and Ex Vivo Anti-HIV-1 Activity and Prolonged In Vivo Half-Life

“…To overcome the limitation of low potency and short in vivo half-life of the peptidic anti-HIV drug enfuvirtide (T20), we introduced a mutation, T639I, and added palmitic acid to HP23-E6-IDL, a peptide-based HIV fusion inhibitor with high potency and good resistance profile [11]. The newly conjugated peptide YIK-C16 is about 4- and 13-fold more potent than HP23-E6-IDL against HIV-1 IIIB and HIV-1 Bal infection, respectively, and about 16-fold more effective than HP23-E6-IDL against infection by HIV-1 mutants resistant to T20 and other HIV fusion inhibitory peptides, T2635 and HP23.…”

“…Recently, we discovered that the addition of three residues, Ile654, Asp655, and Leu656 (IDL), which adopt a hook-like (tail-anchor) structure, to the C-terminus of CHR peptides can greatly enhance their binding to NHR and anti-HIV-1 activities [10], providing a new strategy to design and optimize HIV-1 fusion inhibitors. On the basis of the IDL hook structure, we designed a 32-mer peptide inhibitor (HP23-E6-IDL), which exhibited potent inhibitory activity against HIV-1 of diverse subtypes and tropisms, especially those resistant to other HIV-1 fusion inhibitors [11]. However, similar to other peptide-based drugs, HP23-E6-IDL possesses a short in vivo half-life, which significantly attenuates its potential for development into a new anti-HIV drug.…”

Conserved Residue Asn-145 in the C-Terminal Heptad Repeat Region of HIV-1 gp41 is Critical for Viral Fusion and Regulates the Antiviral Activity of Fusion Inhibitors

“…Recently, Su and coworkers identified a shallow pocket in the N-terminal region of the NHR trimer (termed N-pocket) and intentionally designed fusion inhibitors that can fit this site [26,27,28]. By replacing three C-terminal residues of SC29EK- and MT-SC29EK-based peptides with an artificial IDL (Ile-Asp-Leu) anchor, the authors generated two new peptides (designated WQ-IDL and MT-WQ-IDL) with significantly increased anti-HIV activities.…”

“…In the helical wheel and hairpin models (Figure 1B,C), Asn-145 locates at the “ a ” position in the CHR helix and interacts with Val-38 at the “ e ” position of the NHR helix, which is a key component of the “GIV” motif that critically determines T20 resistance. Recently, Asn-145 was intentionally substituted by a C-terminal IDL anchor to generate fusion inhibitors that can target a newly-defined shallow pocket at the N-terminal site of the NHR trimer [26,27,28]. We have comprehensively characterized Asn-145 from multiple angles and demonstrated its important roles for Env-mediated HIV-1 entry and fusion inhibitors.…”

The Antihistamine Drugs Carbinoxamine Maleate and Chlorpheniramine Maleate Exhibit Potent Antiviral Activity Against a Broad Spectrum of Influenza Viruses

“…After culture at 37°C for 48 h, the luciferase activity was measured using the Luciferase Assay System (Promega) with a microplate luminometer (Ultra 384, Tecan, NC, USA). The inhibitory activity of a test compound on entry of HIV-1 IIIB infection were determined as described previously ( Su et al, 2017a , b ). Series dilution of CAM and SCM were incubated with 50 μL 100 TCID 50 of the HIV-1 at 37°C for 1 h and then 10 4 MT-2 cells per well were added into the 96 well plate.…”