Quaternary protein mimetics of gp41 elicit neutralizing antibodies against HIV fusion‐active intermediate state

Abstract

During viral entry, the fusogenic state of human immunodeficiency virus Type 1 (HIV‐1) envelope protein gp41 is a quaternary structure consisting of three gp41 glycoproteins, each with two conserved helical domains (N‐HR and C‐HR). Thus far, the examination of monomeric gp41 peptides as an immunologically focused approach to vaccine design has not been successful. Here we report an approach using quaternary protein mimetics (called 3α mimetics) that are based on the gp41 N‐HR and C‐HR domains to closely mimic the fusogenic state and overcome the deficiencies of the monomeric peptide approach for synthetic vaccine design. The 3α mimetics are conveniently prepared by chemoselective ligation of unprotected monomeric peptides to an interstrand linker, and display enhanced conformational stability compared to the corresponding monomers. The 3α mimetics with or without a covalently attached T‐helper epitope were immunogenic and elicited antisera that bound both recombinant gp160, which contains gp41, and HIV‐1 virions and immunoprecipitated recombinant gp41. Anti‐3α mimetic antisera neutralized viral infectivity against R5‐ and X4‐tropic strains of HIV‐1 at 31.5°C. The results suggest that a quaternary protein approach to mimic conserved and functional domains of viral envelope proteins is desirable for HIV vaccine development as such antigens are more likely to produce immunologically‐focused and broadly neutralizing antibody responses. © 2008 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 90: 320–329, 2008.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

Multimerized HIV‐gp41‐derived peptides as fusion inhibitors and vaccines

“…The linker tethered to this template, whose synthesis was reported previously, has three branches of equal length and possesses the hydrophilic structure and ligation site necessary for coupling with N36RE. The template obtained, with its three‐armed aldehyde scaffold (Figure B), was conjugated using thiazolidine ligation for chemoselective coupling with Cys‐containing unprotected N36RE (N36REGC) to produce the trimer triN36e (Figure C). Judging by CD spectrometry, the helical content of the trimer triN36e is higher than that of the monomer N36RE, and the mixture of triN36e and a C34‐derived monomer peptide, C34RE, has a high molecular ellipticity, as an absolute value, comparable with that of triN36e alone, indicating that C34RE interacts with tri36e, thereby inducing a higher helical form .…”

Mode of Action of the Sulfhydryl Group in Virolytic Peptide Triazole Thiol Inhibitors of HIV-1

“…Replacing residues at positions 30 and 33 (hCRF numbering) of [D-Phe 12 , Nle 21,38 ]-hCRF(12-41) with a glutamic acid and lysine, respectively and linking these two residues through a lactam bridge produced astressin {cyclo (30)(31)(32)(33)[D-Phe 12 , Nle 21,38 , Glu 30 , Lys 33 ]h/rCRF(12-41)} a more potent antagonist than its linear analog [1]. The cyclic peptide showed enhanced α-helical conformation [2].…”

Structure-Based Design of a Protein Immunogen that Displays an HIV-1 gp41 Neutralizing Epitope

“…A recently developed ‘antigenically resurfaced’ gp120 antigen 3 has been successfully utilized to isolate new and potent broadly neutralizing antibodies, but it is not yet known how that construct will perform in immunization trials. Other approaches to immunogen design include constraining peptide fragments of the parent protein to adopt conformations similar to those in their gp120 or gp41 parental proteins 28; 29; 47; 48; 49; 50; 51; 52; 53; 54; 55 . Such approaches utilize the introduction of disulfide bonds or other linkers or the inclusion of unusual amino acids that stabilize secondary structure.…”