DNA vaccine set to tackle HIV infection.

Administration has for the first time given researchers permission to inject a vaccine made from simple DNA into healthy, uninfected volunteers. The small trial, involving a potential AIDS vaccine, should begin in the next few months and will be conducted by investigators from the University of Pennsylvania in Philadelphia and the biotech firm Apollon in Malvern, Pa.

The experiment marks another major milestone for the emerging technology of DNA vaccines. In ongoing trials, people with advanced cancer and people infected with HIV, the AIDS virus, have received DNA injections.

The new HIV trial will be the first conducted with the hope of preventing infection. Investigators suggest that it sets the stage for the testing of DNA vaccines against a wide array of viruses and bacteria.

"This really opens up the field," says David B. Weiner of the University of Pennsylvania, who announced news of the trial at an international meeting on DNA vaccines held in Bethesda, Md. Over the last few years, investigators have found, to their surprise, that simply injecting a gene into an animal elicits an immune response to the protein that the gene encodes (SN: 1/1/94, p. 6; 6/3/95, p. 343). The vaccine in the new trial is made from a gene that codes for one of the proteins that form the surface of the AIDS virus. Consequently, this DNA vaccine should generate antibodies to the AIDS virus and activate immune cells that kill the virus.

Though investigators hope that the vaccine will prevent HIV infection, the primary purpose of this initial study is to assess the safety of injecting the pure DNA. All available data suggest that injected genes survive only briefly in the body, but there are still concerns that this genetic material may become permanently integrated into a person's genome, with undesired consequences.

Since the cancer and HIV-positive patients already injected with DNA have reported no major side effects after several months, FDA decided it would allow the new trial in uninfected volunteers.

"Now that we've gathered more data, we're ready to move forward. We're all very excited," says Kathryn Zoon, director of FDA's Center for Biologics Evaluation and Research.

Researchers have a number of reasons to hope that the DNA-based AIDS vaccine might be more effective than injection of the HIV protein itself. The two approaches, according to animal data, sometimes provoke different immune responses. DNA-based vaccines, for example, appear to stimulate a stronger, longer-lasting response from infection-fighting immune cells.