AIDS vaccine: Preliminary but promising
Researchers last week reported a series of significant, incremental steps toward a vaccine to protect against AIDS. They emphasize that general availability of such a vaccine remains, at minimum, many years away. But the recent progress brightens what has been an extremely downbeat assessment of the prospects for an AIDS vaccine.
Speaking in Montreal, Quebec, at the Fifth International Conference on AIDS, Jonas Salk of the Salk Institute for Biological Sciences in San Diego presented early but encouraging results from experiments in chimpanzees and humans infected with the AIDS virus, HIV. Unlike most experimental AIDS vaccines, which use small portions of HIV to trigger a protective immune response, Salk's vaccine contains whole AIDS viruses killed by treatment with chemicals and radiation. Salk used a similar method in the 1950s to make the first commercial vaccine against polio.
While other experimental AIDS vaccines use proteins from HIV's outer envelope to stimulate immunity, Salk's chemical/radiation treatment disintegrates this envelope. Yet the vaccine appears to eliminate HIV from chimpanzees, suggesting it might not only prevent infection but also halt disease progression in already-infected individuals.
Salk and Clarence J. Gibbs of the National Institutes of Health vaccinated two HIV-infected chimps and one uninfected chimp, then followed up with two boosters. Three months later, they infected the three chimps and an unvaccinated control chimp with large "challenge" doses of live HIV. Following that challenge, they detected no HIV in the first two chimps. The originally uninfected, vaccinated chimp tested HIV-positive for a few months after the challenge but has remained HIV-free since then. The unvaccinated chimp's infection has worsened.
In tests assessing safety and side effects rather than effectiveness, the researchers also vaccinated HIV-infected humans showing …