(HIVNET Protocol D01.3)

Some of the participants in the HIVNET Vaccine Preparedness Study (VPS) have had dozens of recent exposures to HIV through unsafe sex or sharing needles with HIV positive partners, without becoming infected themselves. The purpose of this study is to learn whether people with many exposures to HIV who remain uninfected have immune responses to HIV that are different from the immune responses of people who have never been exposed.

Laboratory tests in this study will look at a variety of possible immune responses, involving both antibody and cellular responses in the blood and in other fluids, for example, semen, saliva, and vaginal fluids.

Up to 70 VPS participants who have had at least twenty unprotected receptive exposures (sexual or through drug injection) to a known HIV-infected partner in the prior year, or 100 or more in the prior three years. For each VPS participant, two control subjects (matched by age, sex, race, study site, and pregnancy history) who have not been exposed to HIV will be recruited from outside the VPS.

• Denver Department of Public Health, Denver, CO
• Fenway Community Health Center, Boston, MA
• Howard Brown Health Center, Chicago, IL
• New York Blood Center, New York, NY
• New York University Medical Center, New York, NY
• San Francisco AIDS Office/Public Health Foundation Enterprise Inc., San Francisco, CA
• University of Pennsylvania, Philadelphia, PA
• University of Washington, Seattle, WA

Participants will be asked about behaviors that may have exposed them to HIV. They will receive a physical exam, and will be asked to provide blood and other specimens for laboratory analysis.

Laboratory studies will compare responses from the controls and from exposed but uninfected participants on to a variety of tests of immune system function. If the tests are able to show a difference between the exposed participants and the unexposed controls, participants will be asked to complete three follow-up visits over 12 months to evaluate how long the altered immune response lasts. Researchers will also expand the study to included another set of matched control participants from the same at-risk group as the exposed but uninfected participants.

Enrollment began in April 1997; as of June 1998 18 cases and 23 controls have been enrolled. No additional cases are expected to enroll. Based on results so far, researchers decided to ask participants to return for a third visit. All visits are expected to be completed by Fall 1998.