Determinants of Human Immunodeficiency Virus Type 1 Resistance to gp41-Derived Inhibitory Peptides

Abstract

A synthetic peptide, DP178, containing amino acids 127 to 162 of the human immunodeficiency virus type 1 (HIV-1) gp41 Env glycoprotein, is a potent inhibitor of virus infection and virus mediated cell-to-cell fusion (C. Wild, T. Greenwell, and T. Matthews, AIDS Res. Hum. Retroviruses 9:1051–1053, 1993). In an effort to understand the mechanism of action of this peptide, we derived resistant variants of HIV-1IIIB and NL4-3 by serial virus passage in the presence of increasing doses of the peptide. Sequence analysis of the resistant isolates suggested that a contiguous 3-amino-acid sequence within the amino-terminal heptad repeat motif of gp41 was associated with resistance. Site-directed mutagenesis studies confirmed this observation and indicated that changes in two of these three residues were necessary for development of the resistant phenotype. Direct binding of DP178 to recombinant protein and synthetic peptide analogs containing the wild-type and mutant heptad repeat sequences revealed a strong correlation between DP178 binding and the biological sensitivity of the corresponding virus isolates to DP178. The results are discussed from the standpoints of the mechanism of action of DP178 and recent crystallographic information for a core structure of the gp41 ectodomain.

Design of Novel HIV-1/2 Fusion Inhibitors with High Therapeutic Efficacy in Rhesus Monkey Models

“…While the pocket-binding sequence has been used for inhibitor design, little attention has been paid to the C-terminal tryptophan-rich motif (TRM) of T-20, which is thought as a lipid binding domain (LBD) that can interact with the cell membrane to confer antiviral activity (30)(31)(32). Indeed, the mechanism of action of T-20 and its structural properties remain elusive, as exemplified by the fact that its target sites have been suggested to be on the NHR helices (8,11), the CHR helices (33,34), the fusion peptide (35,36), or the transmembrane domain (32) of gp41 and the coreceptor binding site of gp120 (32,(37)(38)(39)(40). We are interested in revisiting the mode of action of T-20 in an attempt to develop fusion inhibitors that differ from those specifically targeting the gp41 pocket site, such as LP-11 and LP-19 (19,20).…”

“…T-20 is effective in combination therapy of HIV-1 infection, but it has relatively low antiviral activity and a short half-life, thus requiring high-dose injections (90 mg twice daily). More disappointingly, T-20 inherits a low genetic barrier to inducing drug resistance (11,12). In succession to T-20, T1249 was designed as a second-generation fusion inhibitor with significantly improved pharmaceutical profiles (13,14); however, its clinical development was stopped due to formulation difficulties.…”

Novel screening systems for HIV-1 fusion mediated by two extra-virion heptad repeats of gp41

“…This hypothesis is strongly supported by the introduction of a site of mutations for T-20 resistance in vivo. Variants isolated from T-20 treated patients frequently display mutations in the HR1 region, especially at amino acids 36-45, including D36G/V/S, V38A/E and N43D (Aquaro et al, 2006;Cabrera et al, 2006;Mink et al, 2005;Poveda et al, 2002;Rimsky et al, 1998;Wei et al, 2002) (Fig. 1).…”

Mechanism of Membrane Fusion by Viral Envelope Proteins

“…Fold-back. The best evidence for an extended "prefusion intermediate," with the fusion peptides inserted into the target cell membrane but with the C-terminal parts of the fusion protein still at the opposite end of the molecule, comes from work on HIV-1 gp41 (Furuta et al, 1998;Rimsky et al, 1998) (see later). In the mature HA trimer at neutral pH, the long axial helices diverge from each other at about the position at which the folding back occurs ( Fig.…”

“…Peptides derived from the outer layer of rearranged gp41 inhibit fusion and viral infectivity by targeting the intermediate shown in Fig. 3B (Rimsky et al, 1998). Evidence for the properties of this intermediate comes from kinetic studies, in which binding of outer layerderived peptides has been analyzed by detecting their effects on fusion (Furuta et al, 1998;Jones et al, 1998;Munoz-Barroso et al, 1999).…”