More than 22 million people worldwide have died of AIDS. With millions of new infections each year, a safe and effective AIDS vaccine is imperative.In the past year or so, groups at Harvard Medical School, Beth Israel Deaconess Hospital and Emory University have reported some success in controlling the proliferation of an HIV-like virus in monkeys by vaccinating with DNA fragments similar to those found in that virus.
However, a glance at the history of disease control shows that the most effective vaccines, e.g., the polio vaccine, have been based on live viruses. These can be absorbed through the mouth or nose with no need for an injection, making them easier and cheaper to administer, especially in developing countries, which are suffering most from the AIDS epidemic.
The main problem with using this approach for AIDS has been the risk of disease associated with a live HIV vaccine.
But in 1995, John Rose and colleagues at Yale University's School of Medicine developed a method of engineering the Vesicular Stomatitis Virus (VSV), an RNA virus, to express foreign genes. "Having developed the VSV recombinants, you can put the HIV genes, or just about anything into the VSV genome," says Rose.
Now Rose and colleagues report in today's issue of Cell that they have successfully vaccinated 7 rhesus monkeys against an HIV-like virus using live VSV expressing the AIDS virus genes.
When the monkeys were later exposed to the AIDS virus, they fared better than a control group, with none succumbing to AIDS over a period of 14 months and several actually managing to clear the HIV infection, or at least reduce their viral load below detectable levels.
Seven out of eight control monkeys had progressed to AIDS within about six months of infection.
"This vector system may also be valuable if we're going to generate a vaccine that can protect completely against infection in the first place," Rose says.
One problem with a live vaccine is that it will be much harder for the researchers to gain FDA approval for trials. However, they are currently putting together a protocol for Phase I trials with Wyeth Lederle Vaccines in Philadelphia, Pa.
[Contact: John Rose]
07-Sep-2001
