Varied AIDS Virus May Defy Efforts to Create Vaccine

WASHINGTON — The virus suspected of causing AIDS has so many variations in its genetic structure that developing a vaccine against the disease may be difficult, if it can be done at all, researchers said Thursday.

Scientists at the National Cancer Institute said that they looked at samples of the suspect virus found in 18 patients with AIDS or at high risk of getting the disease, and each isolated virus showed a different variation in its genetic structure.

The study, to be published today in the journal Science, means that it could be difficult to find a common site on the viruses that could be targeted for preventive and therapeutic measures, they said.

To develop a vaccine, researchers say, they need to find a common protein region, preserved in all variations of the virus, that triggers an immunologic response.

If the body has been previously primed to produce antibodies to this area, such as through vaccination with the protein produced by the targeted genetic region, then it may be possible for people to resist the virus.