AIDS research: from vaccines to safer sex.

This week, researchers from around the world met at the Tenth International AIDS Conference in Yokohama, Japan, to report scientific findings on topics ranging from vaccine development to long-term survivors of HIV infection. At the same time, several major journals published updates on this devastating disease.

* At the AIDS meeting, National Institute of Allergy and Infectious Diseases (NIAID) Director Anthony S. Fauci and his colleagues reported preliminary results from a study of people who had remained healthy despite being infected with HIV for about a decade. Their study suggests that such people may show a more aggressive immune response to HIV, the virus that causes AIDS. Compared to HIV-infected people who progressed to AIDS, those who did not had very high concentrations of HIV-destroying antibodies.

* In the Aug. 10 JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION, Robert B. Belshe of the St. Louis University School of Medicine and his colleagues demonstrated that a genetically engineered vaccine triggers the production of antibodies that attack several strains of HIV.

The study involved 57 volunteers who were not infected with the AIDS virus. Forty-eight of them received varying amounts of vaccine, a product genetically engineered to look like the gp 120 protein that sits on the surface of the AIDS virus. The remaining nine recruits got an inactive placebo.

"We were delighted to learn that two shots of the vaccine stimulated antibodies that could attack and kill a strain of HIV in the laboratory," Belshe says. After giving three or four doses of vaccine, the researchers documented antibodies that neutralize additional strains of HIV. An effective vaccine must recognize and kill many different types of HIV, Belshe points out.

The vaccine, made by Genentech of South San Francisco, seemed to spur the production of an antibody that attacks virus-infected cells. The body may rely on such antibodies to clear the blood of HIV-tainted cells, an important step in fighting off infection.

* At the AIDS meeting, M. Juliana McElrath of the University of Washington in Seattle presented results from a larger study of the same Genentech gp 120 vaccine and another gp 120 vaccine, this one made by Biocine Co. of Emeryville, Calif. The study involved 296 people, including some volunteers at high risk of HIV infection. Thirty-nine people received a placebo; the remainder got either the Genentech or the Biocine vaccine.

This study revealed no safety problems with either product. The side effects appeared mild, says one coauthor, Patricia Fast of NIAD. Some people experienced a mild malaise after getting the injections, she noted.

Both vaccines spurred the production of antibodies that killed several laboratory strains of HIV, Fast says.

While the antibodies triggered by both of these experimental vaccines can neutralize HIV growing in laboratory culture, they do not appear to destroy HIV taken directly from the bloodstream of AIDS patients, Belshe cautions. Such uncertainties helped fuel the decision to hold off on expanded testing of these vaccines (SN: 6/25/94, p.404).

* In the Aug. 11 NEW ENGLAND JOURNAL OF MEDICINE, Isabelle de Vincenzi of the Saint Maurice National Hospital in France and her colleagues address the question of safe sex. The team studied 256 uninfected men and women. All were in a hetero-sexual relationship with an HIV-infected partner.

The researchers discovered that only 124 of the couples used condoms consistently. More important, however, none of the healthy partners in this group became infected with HIV, despite an estimated 15,000 episodes of intercourse. In contrast, 121 couples used condoms on occasion; the study found that 12 of the healthy partners in this group became infected. Eleven couples refused to answer questions about condom use.

Such findings help scientists quantify more precisely the protection offered by condoms, according to an editorial written by Anne M. Johnson of the University College Medical School in London. "We should now have greater confidence that condoms really can save lives."