Genetically Engineered AIDS Vaccine to Be Tested In Africa
San Franscisco Chronicle 20may00

A unique oral AIDS vaccine built from genetically engineered bacteria and aimed at the body's most vulnerable organs is being developed at the research institute headed by famed virologist Robert Gallo, scientists announced yesterday.

Although Gallo himself cautioned that the vaccine is still untested in humans, Dr. Francis Omaswa, Uganda's health services director, said plans are already set for the first clinical trials. The trials, to be conducted on volunteers in the East African nation of 21 million people, could begin within 18 months, Omaswa said.

Uganda is the only African nation to aggressively implement a significant range of AIDS prevention services, Omaswa said, but 1.5 million people there are already infected with the AIDS virus, and more than a million children have already been orphaned by the epidemic.

The Gallo team's AIDS vaccine is the first designed as a pill to be taken orally; other AIDS vaccines are in liquid form and must be administered by injection. The pills would be inexpensive to manufacture and easy to distribute widely and administer safely by community health care workers, who would need little or no medical training, Gallo said.

Dr. Anthony Fauci, the U.S. government's leading AIDS researcher who directs the National Institute of Allergy and Infectious Diseases, said in a telephone interview yesterday that the vaccine developed by Gallo's team is ``theoretically the right approach.'' But, like Gallo, he warned, ``We've been fooled so many times about new vaccines that I've hesitated to talk about this one until now, but I really like it.''

Development of the vaccine at Gallo's Institute of Human Virology at the University of Maryland is being supported by a 4-year-old activist organization called the International AIDS Vaccine Initiative.

The initiative -- which is largely funded by the Rockefeller Foundation, the William Gates Foundation and U.N. agencies -- engages in what it calls ``social venture capitalism.'' Money is funneled to those researchers who guarantee that their vaccines, if successful, will be produced cheaply and be readily available to poor Third World countries.

Although many drug companies have developed possible AIDS vaccines, neither they nor federal agencies have earmarked a significant part of their research money for the vaccine effort. None has focused on an oral vaccine, and only one of the other 28 AIDS vaccines that have been clinically tested in the U.S. and around the world has shown any real promise.

`DESPERATE NEED'

That single promising vaccine, called AIDSVAX, must be administered by injection, and is now in the final phase of human testing in Thailand and in several American cities. It is made by VaxGen, a Brisbane biotechnology firm whose scientists began developing it more than 15 years ago.

``Everyone is aware that what we desperately need is a preventive vaccine,'' Gallo said in a telephone interview. ``And while I'm not expecting this one to be a home run with the bases loaded, it does look very exciting.''

Dr. George Lewis, vaccine research director at Gallo's institute, said it has taken six years to develop the oral AIDS vaccine, but now, he said, ``we want to make sure it moves into the field as fast as possible.''

To make the vaccine, the researchers have used the salmonella bacterium. It is a common cause of food poisoning in industrialized countries and the source of deadly typhoid fever in developing nations where poor sanitation and contaminated drinking water is widespread.

The scientists remove one segment of genes from the salmonella microbe so that it can no longer cause disease, then insert an incomplete set of genetic material from HIV, the AIDS virus, into the bacterium.

VULNERABLE TARGETS

The so-called DNA vaccine in pill form would then pass through the intestinal tract and reach particularly vulnerable targets, among them the rectum and the vagina, where moist mucus tissues are a fertile breeding ground for HIV to replicate. The viral material in the vaccine would then trigger what is called mucosal immunity, as opposed to the cellular immunity that most other AIDS vaccines are designed to induce.

The new oral vaccine should cost less than $1 per dose, according to the leaders of the AIDS Vaccine Initiative, which has committed at least $3 million over the next three years for the testing program in Uganda.

Since the onset of the global AIDS epidemic, scientists have watched as the virus continues to mutate. Today there are many different strains in different regions of the world. As a result, Gallo said, the Uganda vaccine -- if it proves effective -- would only prevent the HIV strains prevalent in East Africa.

But if the vaccine is useful there, then segments of other HIV genes from other parts of Africa -- or from India and Southeast Asia as well -- could be readily spliced into the salmonella microbes to target populations in those regions, Gallo said.

The International Vaccine Initiative was created in 1996 by a group of AIDS activists and researchers angry at the slow pace of vaccine development. They have since formed partnership agreements with university researchers and health services in several European and African countries.

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