San Francisco Chronicle - Friday, September 7, 2001
Carl T. Hall, Chronicle Science Writer

Using a weakened form of an animal virus called VSV as the delivery system, scientists at Yale University School of Medicine said the new vaccine would be cheaper to manufacture and easier to administer than other alternatives. Scientists hope that a single dose, given in the form of a nose spray or drops, could provide longtime protection against AIDS.

There's no direct evidence the approach will work in people. And because the vaccine uses a live virus -- even though one that rarely infects humans in most of the world and has not been shown to cause serious illness -- it will take extensive testing to make sure it is safe.

"The road ahead is very long," said lead investigator John Rose, a professor of pathology and cell biology at Yale.

In the experiments, monkeys were exposed to the AIDS virus and then monitored to see whether they developed signs of the disease. Rose reported the results at a conference on AIDS vaccines in Philadelphia yesterday and in the current issue of the journal Cell.

Seven rhesus monkeys that received the vaccine have remained healthy and essentially clear of the virus for as long as 14 months, despite repeated infection with a hybrid of the human and monkey forms of the AIDS virus.

By comparison, seven of eight control animals, which were not vaccinated, all came down with the disease when subjected to the virus. Those animals were euthanized.

In an update of previously reported experiments, two other potential AIDS vaccines also are showing encouraging results in monkeys, researchers said yesterday at the same conference.

But Rose said the new approach might offer some advantages because it would not require multiple injections, making it more practical to give to large numbers of people, particularly in developing nations where the AIDS epidemic is most severe.

It also would be easy and cheap to make. Based on animal studies, "it might be possible to produce sufficient AIDS vaccine for more than 1 billion people starting from one liter" of concentrated starting material, researchers noted.

Live virus vaccines have proved effective against other diseases, including polio and smallpox, but scientists have been leery of trying that with live HIV because of the obvious hazards.

The Yale team, collaborating with scientists at several other institutions including the University of California at San Francisco's Gladstone Institute of Virology and Immunology, used a modified form of VSV, or vesicular stomatitis virus, engineered to carry AIDS viral proteins.

In the monkeys, those viral proteins were enough to stimulate a strong cellular immune response against a form of HIV, but did not make the animals sick in any way, scientists found. The big unanswered question now is whether the same response can be safely elicited in people.

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