HIV-1 neutralizing antibodies elicited by the candidate CBD1 epitope vaccine react with the conserved caveolin-1 binding motif of viral glycoprotein gp41

Abstract

To date, candidate HIV-1 vaccines that have been tested in clinical trials have failed to induce broadly neutralizing activities and/or antibodies that inhibit infection by primary isolates of HIV-1. We recently identified a conserved caveolin-1 binding motif, WNNMTWMQW, in the ectodomain of HIV-1 transmembrane envelope glycoprotein gp41. We designed the synthetic CBD1 peptide SLEQIWNNMTWMQWDK, corresponding to the consensus caveolin-1 binding domain (CBD) in gp41, and showed that it elicits in rabbits the production of antibodies that inhibit infection of primary CD4(+) T lymphocytes by various primary HIV-1 isolates. Although a conserved and highly homologous caveolin-1 binding motif is present in the transmembrane envelope glycoprotein of different HIV-2 isolates, anti-CBD1 immune sera do not inhibit HIV-2 infection. Here we show that anti-CBD1 antibodies are directed against the conserved caveolin-1 binding motif WNNMTWMQW in the CBD1 epitope. In spite of this, anti-CBD1 antibodies do not react with the CBD2 peptide SLTPDWNNMTWQEWER, corresponding to the potential consensus caveolin-1 binding domain in HIV-2. The presence of a conserved proline residue upstream of the caveolin-1 binding motif in CBD2 might affect the presentation of this motif, and thus account for the lack of reactivity of the immune sera. Anti-CBD1 antibodies therefore appear to be directed against a conformational epitope mimicked by the synthetic CBD1 peptide. In accordance with this, anti-CBD1 immune sera react with the native but not denatured gp41. The reactivity of anti-CBD1 immune sera with a highly conserved conformational epitope could explain the broad inhibitory activity of such antipeptide antibodies against HIV-1 isolates of various clades.

Caveolin-1 suppresses Human Immunodeficiency virus-1 replication by inhibiting acetylation of NF-κB

“…A recent study demonstrated that caveolin-1 interacts with HIV-1 envelope proteins (gp41) and potentially facilitates entry (Hovanessian et al, 2004). A number of reports have indicated that caveolin-1 plays some role in modulating viral pathogenesis in vivo (Benferhat et al, 2009a; Benferhat et al, 2009b; Benferhat et al, 2008; Fermin and Garry, 2005; Hovanessian et al, 2004; Huang et al, 2007; Rey-Cuille et al, 2006; Wang et al, 2010). Based on some of our previous studies on the role of cholesterol in HIV-1 biology, we initially suspected that the mechanism of HIV-1 inhibition by caveolin would be linked to its role as a cholesterol transporter.…”

Evaluation of recombinant Onchocerca volvulus activation associated protein-1 (ASP-1) as a potent Th1-biased adjuvant with a panel of protein or peptide-based antigens and commercial inactivated vaccines

“…Ovalbumin (OVA, Sigma, St. Louis, MO) and HIV peptide (HIV-p) which is derived from the caveolin binding domain of the HIV-1 gp41 (aa 618−637: SLEVIWNNMTWMEWEREIDN) [13] were first used as the model antigens to test the adjuvanticity of the ASP-1 protein. The OVA was selected because it does not usually induce immune responses without the help of adjuvants [14,15].…”

The Integrity of α-β-α Sandwich Conformation Is Essential for a Novel Adjuvant TFPR1 to Maintain Its Adjuvanticity

“…As described previously [26][27][28][29][30], the truncated fragments of TFPR1 were designed and inserted into the pQE-30 vector (containing 6 × His-tag coding sequence), and expressed in E.coli. Because the recombinant proteins were expressed in the form of inclusion bodies, after the proteins were purified by Ni-NTA chromatography and dissolved in 8 M urea, the soluble denatured proteins were refolded by gradient dialysis in 6 M, 4 M and 2 M urea in tris-glycine buffer, followed by Laemmli buffer and PBS.…”

“…To verify whether purified TFPR1 has the capacity to enhance the immunogenicity of B cell epitope-based peptide antigen, HIV-1 CBD [28,29], a 20 aa HIV-1 gp41 peptide, was synthesized and used as immunogen. BALB/c mice were immunized intramuscularly with HIV-1 CBD in the presence or absence of TFPR1, and alum was used as an adjuvant control.…”