New Trial of HIV Vaccine in Gay Men Begins

An AIDS vaccine trial has begun enrolling men who have sex with men (MSM) in 12 US cities. The HVTN 505 study is designed to see whether a two-part vaccine regimen decreases viral loads among participants who later become infected with HIV.

"It is designed to find cells already infected and reduce the amount of virus in people if they do get infected," said Jonathan Fuchs, director of vaccine studies at the San Francisco Department of Public Health. "If we get clues that we can accomplish that, it will be a huge next step in developing a safe and effective vaccine."

The two-part vaccine candidate consists of three recombinant DNA-based primers and one booster to stimulate the immune system. The booster vaccine contains weakened adenovirus type 5 (Ad5), a common virus that normally causes colds. Disabled so as not to cause colds, the Ad5 booster will encode HIV proteins found in HIV and on the virus' outer envelope. Neither of the vaccines contains HIV, nor can they infect participants with HIV.

While the failed STEP vaccine trial also used Ad5, the HVTN trial's booster deletes more of Ad5's genes. Each of the shots in HVTN 505 will also contain more pieces of HIV DNA than the STEP vaccine did.

The trial is recruiting 1,350 HIV-negative, circumcised MSM ages 18-45 who do not have antibodies to Ad5. In San Francisco, researchers are looking for 120 Bay Area MSM and will launch a locally produced campaign for volunteers on Dec. 1, World AIDS Day. Bus shelter ads were planned for Oct. 1 in some of the 12 cities.

For more information, visit www3.niaid.nih.gov/news/QA/HVTN505qa.htm and www.hopetakesaction.org.

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