Baltimore researchers plan human trials of AIDS vaccine

Safety tests could start in 18 months if approved

May 21, 2000|By Jonathan Bor | Jonathan Bor,SUN STAFF

Researchers at Baltimore's Institute of Human Virology have announced plans to begin human tests of an oral AIDS vaccine that they say would be cheaper and easier to administer than injectable vaccines now being tried.

Testing of a vaccine for the human immunodeficiency virus (HIV), which causes AIDS, should begin within 18 months. Testing will be done on volunteers in Baltimore and in Uganda, one of the many African nations ravaged by the fatal disease. The first trial will determine whether the vaccine is safe, and could give way to further studies measuring effectiveness.

Dr. Robert Gallo, the pioneering virologist who heads the institute, said he doubted that the formula for this vaccine will be the final answer to AIDS protection - a goal that has eluded scientists for 20 years - but could prove a valuable first step.

"I don't feel this announcement today is an answer to a preventive HIV vaccine, though nothing in this field shocks me anymore," Gallo said Friday.

Before it can begin, the trial must be approved by the U.S. Food and Drug Administration.

Despite the introduction of many powerful drugs against AIDS, a vaccine is widely seen as the only way to stem a pandemic in which about 35 million people have been infected worldwide. The drugs, which fight the virus once it has taken hold, cost many thousands of dollars, well beyond the means of people in poor nations where most of the cases occur.

In contrast, an effective vaccine would prevent people from acquiring the disease and could be taken in just a few doses. More than 20 vaccines are being tested, but only one has reached large-scale trials involving humans. It could be years before this vaccine reaches that stage of testing.

For Gallo's institute, the oral vaccine is a long-awaited entry into the quest for a viable AIDS vaccine. Gallo, a co-discoverer of the HIV and developer of the first blood test for infection, opened the institute four years ago at the University of Maryland, Baltimore.

Funding for the study comes from the International AIDS Vaccine Initiative, a private, nonprofit organization that is trying to speed the development of a vaccine.

Called a "bio-robot," the vaccine uses salmonella bacteria to deliver genetic material that carry the code for a small piece of the AIDS virus. The bacteria are weakened so that they cannot cause disease. In theory, they are capable of infecting intestinal cells and turning them into vaccine factories. Once inside the intestines, the genetic material would begin producing proteins that make up a piece of HIV's protein coat. Scientists hope this will fool the immune system into mounting a defense against the disease.

The vaccine could be taken by mouth or nasal spray. Vaccines based on bacteria are much cheaper to make than those that use viruses and are capable of holding much larger amounts of genetic material.

Seth Berkley, president of the International AIDS Vaccine Initiative, said they could ultimately cost less than $1.

Researchers will not be able to first test the vaccine on primates such as monkeys or apes because salmonella does not infect them.

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