Hopes of finding an effective HIV vaccine were dashed last fall after human trials were stopped over reports that some volunteers in trial groups who received the experimental vaccine MRK-Ad5 had contracted HIV, the virus believed to cause AIDS.

The news rocked HIV vaccine researchers, and raised questions about funding for this line of research. The National Institute of Health will spend $497 million on HIV vaccine research in 2008.

The setback was disappointing, says Dr. Michael Keefer, an HIV vaccine researcher at the UR, but research should continue because the trial failures still produce knowledge about the immune system, and how to combat HIV.

The latest round of vaccines took the approach of increasing "killer" T-cells, one of the immune system's key defense mechanisms. T-cells mount aggressive attacks on viral invaders like HIV, and the vaccine was designed to greatly increase their number so they couldn't be overwhelmed by the virus.

The vaccine used an inactive common cold "adenovirus," as well as inactive HIV. Half of the 3,000-person study was given the vaccine, and the other half was given a placebo. But 82 people later showed they had contracted HIV - 49 of them had received the vaccine, and 33 received the placebo.

"That was the second big story in all of this," Keefer says. "When the trial was stopped, an analysis of the study groups found that if a person had never been infected with the adenovirus, they were more susceptible to HIV transmission."

There were 33 people from Rochester who participated in the vaccine trial, and one person has contracted HIV. The individual received the vaccine, but had not been exposed to the adenovirus. The HIV component of the vaccine has not been implicated as a cause of infection. But participants are counseled to practice safe sex at all times, Keefer says, because the vaccine's efficacy is unknown.

Keefer says funding for research and small trials like those conducted at the UR will likely resume in the future. Besides conducting smaller trials, the UR has been instrumental in tracking research and information on trials all over the world.