The National Institute of Allergy and Infectious Disease (NIAID) announced today (July 17) that it will not conduct a trial of an HIV vaccine that its own Vaccine Research Center (VRC) developed. It was known as the PAVE 100 trial.

"Based on the available scientific information, NIAID has decided that the VRC vaccine regimen did not warrant a trial of this size and scope and that PAVE 100 will not proceed," the NIAID said in a press release

The trial, which was to be carried out by the Partnership for AIDS Vaccine Evaluation (PAVE) and sponsored by NIAID, involved administering a recombinant vaccine based on adenovirus type 5 (Ad5) to 2,400 US men who have sex with other men. The PAVE 100 vaccine was similar to a Merck vaccine involved in a failed trial that was halted last year, except that researchers planned to give a single dose of the Ad5 vaccine after three DNA-based immunizations designed to stimulate the immune system, while the Merck vaccine was administered in three injections with no prior DNA-based priming.

Though the NIH's AIDS Vaccine Research Subcommittee recommended last month going ahead with the PAVE 100 trial, the NIAID decided not to proceed, saying that the vaccine is "scientifically intriguing and sufficiently different from previously tested HIV vaccines to consider testing it in a smaller, more focused clinical study." The agency said that it would "entertain a proposal for an alternative study with one specific goal: to determine if the vaccine regimen significantly lowers viral load -- the amount of HIV in the blood of vaccinated individuals who may later become infected with HIV."