Structure-guided modification and optimization of antibody VRC07

Novel HIV vaccine strategies: overview and perspective

A human immunodeficiency virus (HIV) vaccine remains a central component in the quest to control the worldwide epidemic. To examine the status of the development of HIV vaccines, we review the results of the efficacy trials carried out to date and the immunologic principles that guided them. Four vaccine concepts have been evaluated in HIV-1 vaccine efficacy trials, and the results of these trials have provided significant information for future vaccine development. While one of these trials demonstrated that a safe and effective HIV vaccine is possible, many questions remain regarding the basis for the observed protection and the most efficient way to stimulate it. Novel HIV vaccine strategies including induction of highly potent broadly neutralizing antibodies, use of novel homologous and heterologous vector systems, and vectored immunoprophylaxis seek to expand and build upon the knowledge gained from these trials.

Vectored immunoprophylaxis protects humanized mice from mucosal HIV transmission

The vast majority of new HIV infections result from relatively inefficient transmission^1,2 of the virus across mucosal surfaces during sexual intercourse³. A consequence of this inefficiency is that small numbers of transmitted founder viruses initiate most heterosexual infections⁴. This natural bottleneck to transmission has stimulated efforts to develop interventions aimed at blocking this step of the infection process⁵. Despite the promise of this strategy, clinical trials of pre-exposure prophylaxis have had limited degrees of success in humans, due in part to lack of adherence to the recommended pre-exposure treatment regimens^6,7. In contrast, a number of existing vaccines elicit systemic immunity that protects against mucosal infections, such as the vaccines for influenza⁸ and HPV⁹. We recently demonstrated the ability of vectored immunoprophylaxis (VIP) to prevent intravenous transmission of HIV using broadly neutralizing antibodies¹⁰. Here we demonstrate that VIP is capable of protecting humanized mice from intravenous as well as vaginal challenge with diverse viral strains, despite repeated exposures. Moreover, animals receiving VIP that expresses a modified VRC07 antibody were completely resistant to repetitive intravaginal challenge by a heterosexually transmitted founder HIV strain¹¹, suggesting that VIP may be effective in preventing vaginal transmission of HIV between humans.