Depletion in antibodies targeted to the HR2 region of HIV-1 glycoprotein gp41 in sera of HIV-1-seropositive patients treated with T20.
ABSTRACT The anti-HIV drug T20 is a synthetic peptide derived from the HR2 region of HIV-1 gp41. T20 contains the sequence ELDKWA, which binds the broadly neutralizing antibody 2F5. Using plates coated with T20 or with synthetic peptides and recombinant proteins representing gp120 or gp41 domains, this study investigated by enzyme-linked immunosorbent assay the levels of antibodies directed to the gp160 molecule in patients treated with T20. Analysis of sera obtained before and after administration of T20 indicated that the levels of antibodies directed to T20, to MBP44, a maltose binding protein representing the HR2 region, and to 4765, a synthetic peptide containing the sequence ELDKWA, fell following administration of T20, while the levels of antibodies directed to other regions of gp41 ectodomain and to gp120 remained stable. The decline observed was independent of the viral load and of the total IgG concentration. Follow-up studies with sera obtained from HIV-1-seropositive patients naive to T20 indicated no decline in the level of antibodies directed to HR2 and other regions of gp160. Analysis of sera obtained from a patient after 2 months of T20 treatment interruption showed a level of antibodies to the HR2 region similar to that measured before administration of T20. The addition of increasing amounts of T20 to sera from T20-naive patients decreased the level of serum antibodies against peptide 4765, T20, and MBP44. The observation of antibody depletion by T20 suggests that anti-gp41 antibodies may interfere with T20 treatment by forming T20-antibody complexes.
- SourceAvailable from: Shibo Jiang[show abstract] [hide abstract]
ABSTRACT: The HIV-1 envelope glycoprotein (Env) gp41 plays a crucial role in the viral fusion process. The peptides derived from the C-terminal heptad repeat (CHR) of gp41 are potent HIV fusion inhibitors. However, the activity of these anti-HIV-1 peptides in vivo may be attenuated by their induction of anti-gp41 antibodies. Thus, it is essential to identify antiviral peptides or proteins with low, or no, immunogenicity to humans. Here, we found that the C-terminal fragment (aa 462-521) of the human POB1 (the partner of RalBP1), designated C60, is an HIV-1 fusion inhibitor. It bound to N36, the peptide derived from the N-terminal heptad repeat (NHR) of gp41, and to the six-helix bundle (6-HB) formed by N36 and C34, a CHR-peptide, but it did not bind to C34. Unlike the CHR-peptides, C60 did not block gp41 6-HB formation. Rather, results suggest that C60 inhibits HIV-1 fusion by binding to the 6-HB, in particular, the residues in the gp41 NHR domain that are exposed on the surface of 6-HB. Since 6-HB plays a crucial role in the late stage of fusion between the viral envelope and endosomal membrane during the endocytic process of HIV-1, C60 may serve as a host restriction factor to suppress HIV-1 entry into CD4+ T lymphocytes. Taken together, it can be concluded from these results that C60 can be used as a lead for the development of anti-HIV-1 therapeutics or microbicides for the treatment and prevention of HIV-1 infection, as well as a molecular probe to study the fusogenic mechanism of HIV-1.PLoS ONE 01/2013; 8(5):e66156. · 3.73 Impact Factor