Targeting gp41 as a strategy to induce mucosal and humoral immunity against HIV-1

Abstract

<p>Majority of new HIV-1 infections world-wide occur via the genital tract. Therefore, achieving effective mucosal immunity will be a critical component of vaccine strategies in the prevention and control of infection during early stages of transmission itself. Rigorous efforts have been made to identify conserved epitopes and develop rational design of immunogens, in order to elicit broadly-reactive protective Abs against HIV. Newly emerging data have highlighted the significance of Ab effector functions other than classical IgG-mediated neutralization in HIV infection. In the studies contributing towards this thesis, an optimized vaccine model is described that successfully elicits potent systemic and mucosal Abs against the highly conserved epitopes of the membrane-proximal external region and the coiled coil region of gp41. Intriguing observations are reported on the IgA-inducing capacity of the coiled coil epitope, QARVLAVERY, which highlight the potential of this epitope as an attractive candidate for mucosal vaccines. Most importantly, the epitope-specific Abs proved to be functional in neutralizing HIV in a standardized assay. With particular relevance to mucosal protection, epitope-specific IgA also effectively inhibited the transcytosis of HIV in an optimized transwell assay. The effect of gp41-specific Abs was also assessed against a novel panel of HIV-1 viral clones, and exhibited significant protection. These clones selectively express envelopes from viruses that would be desired targets of prophylactic immune responses, the earliest founder population in the mucosa after virus transmission.</p>