HIV vaccine development: Lessons from the past, informing the future.

In September 2007, a clinical trial (STEP trial) evaluating the candidate HIV vaccine MRK Ad5 HIV-1 gag/pol/nef from Merck & Co Inc was halted at the first interim analysis because the vaccine demonstrated no positive impact on virus acquisition or virus load following infection. Additionally, there was an increased rate of HIV infection in vaccinees who had prior immunity to adenovirus type 5 (Ad5) and/or were circumcised. This failure of the vaccine, as well as the apparent harm caused to some study participants, generated a massive pessimism regarding HIV vaccine development. Concerns regarding the future of HIV vaccine research led to a summit convened by the NIAID in March 2008 to provide new directions in HIV vaccine research. A shift in emphasis focused on three areas: discovery research, animal models and clinical research. In each of these areas, notable new activities have occurred: a wealth of information has emerged from the STEP trial, promising results have been reported on assay development for markers of vaccine-induced immune function, and evaluations of promising new experimental vaccines have occurred in nonhuman primates. Overall, the progress in the field of HIV vaccine research since September 2007 has reinforced the need for a balanced approach between basic vaccine discovery and development, as well as the importance of addressing questions in nonhuman primate studies and clinical trials. This article discusses how past product failures have invigorated the field of HIV vaccine research by addressing critical questions and suggesting additional possible approaches to follow. As a result of the insight gained, a new sense of optimism exists in the field of HIV vaccine research.

Mucosal immunity and HIV/AIDS vaccines. Report of an International Workshop, 28-30 October 2007.

In October 2007, a joint ANRS-NIH workshop was held on "Mucosal immunity and HIV/AIDS vaccines" in Veyrier-du-Lac, France. Goal of the meeting was to discuss recent developments in the understanding of viral entry and dissemination at mucosal surfaces, rationale for designing vaccines to elicit mucosal immune responses by various routes of immunization, and the types of immune responses elicited. Lessons were drawn from existing vaccines against viral mucosal infections, from the recent failure of the Merck Ad5/HIV vaccine and from attempts at mucosal immunization against SIV. This report summarizes the main concepts and conclusions that came out of the meeting.

Current advances and challenges in HIV-1 vaccines.

Recent advances in science, which have aided HIV-1 vaccine development, include an improved understanding of HIV-1 envelope structure and function, expansion of the pipeline with innovative vaccine strategies, promising multi-gene and multi-clade vaccines that elicit cellular immunity, conduct of clinical trials in a global network, and development of validated techniques that enable simultaneous measurement of multiple T cell vaccine-induced immune responses in humans. A common feature of several preventive vaccine strategies now in early clinical trials is their ability in nonhuman primates to attenuate clinical disease rather than completely prevent HIV-1 infection. One vaccine concept has been tested in large-scale clinical trials, two are currently in efficacy trials, and one more is poised to enter efficacy trial in the next few years. Simultaneously, expanded efforts continue to identify new designs that induce mucosal immunity as well as broadly neutralizing antibodies.