The Bill & Melinda Gates Foundation has awarded $15 million to Baltimore AIDS researchers hoping to develop a vaccine that will protect people against most of the viral strains circulating worldwide.
The grant goes to the University of Maryland's Institute of Human Virology, headed by Dr. Robert Gallo, the co-discoverer of the human immunodeficiency virus, which causes AIDS.
Gallo said yesterday that the vaccine is designed to overcome the virus' ability to mutate constantly - a hurdle that has frustrated researchers for more than two decades.
In tests, the vaccine caused monkeys to produce antibodies against a variety of strains. But Gallo cautioned yesterday that years of bench science as well as further testing in monkeys and humans lie ahead before the vaccine can be proved a success.
"We're not announcing a breakthrough," Gallo said in an interview. "It's interesting, and we believe it's important, but we cannot make any predictions with it."
The tests were performed last year by the institute's spinoff, Profectus BioSciences, a Baltimore-area company.
New medications have enabled thousands of people to survive for many years, turning AIDS into a chronic but manageable disease. But the drugs are expensive, must be taken every day and do not cure people.
In theory, a vaccine could prevent people from becoming infected.
"Seeing the end of HIV/AIDS is still a dream," said Dr. E. Albert Reece, dean of the University of Maryland School of Medicine. He called the research "a positive step toward seeing that dream come through." The virology institute is a division of the medical school.
The five-year grant money will be used to develop a vaccine designed by two IHV scientists, Tony DeVico and George Lewis.
Gov. Martin O'Malley, who announced the grant at a State House news conference, said efforts like this could help the nation "unleash the weapons of salvation" and bolster Maryland's efforts to become a center of biotechnology.
A Gates Foundation spokesman was unavailable for comment. Last year, the foundation awarded $287 million in AIDS vaccine grants to investigators in 19 countries.
Historically, many vaccines against human infections have contained weakened or killed versions of the disease-causing microbes. Once given to people, they trick the body into mounting a lasting immune response to fight a natural infection.
But scientists and government regulators have considered this approach too risky when it comes to AIDS, choosing instead to focus on vaccines containing a protein found on the outer coat of the virus.
Gallo said that strategy has failed when applied to AIDS. In experiments, so-called "subunit vaccines" have stimulated antibodies against the strains used to make the vaccines - but not against myriad strains found worldwide or within a single patient.
The new vaccine contains a protein that is normally hidden within the AIDS virus but briefly exposes itself when the virus docks onto a cell and prepares to invade.
Unlike proteins on the outer coat, which constantly change form, this protein remains unchanged, Gallo said.
The university licensed the vaccine to Profectus for testing. The biotech firm, in turn, licensed the vaccine to Wyeth, a pharmaceutical giant that could begin a human trial next year, Gallo said.
In last year's tests by Profectus, four monkeys were vaccinated before being challenged with a virus that is a hybrid of HIV and a similar virus that infects monkeys.
"After a period of time, the virus was cleared - there was no detectable virus in plasma," Gallo said. When the animals were killed, researchers could find viral particles in only one of the four monkeys - and in only one tissue.
Overcoming the changeability of the AIDS virus has been an "enormous problem" for vaccine researchers, said Dr. Robert Siliciano, an AIDS researcher at the Johns Hopkins School of Medicine.
The problem is far greater than the one facing the makers of influenza vaccines, who must tailor a new weapon every year against the flu strain arising out of Asia. With AIDS, the amount of variability found within a single patient is comparable to the amount seen among all flu patients worldwide in a given year, he said.
"It gives an idea of the difficulty of making a vaccine that targets the coat protein," Siliciano said. "The problem keeps getting worse and worse by the minute."