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. Last Updated: 07/27/2016

Proposed Test of Vaccine For AIDS Sparks Debate

WASHINGTON -- At first blush, the idea has a certain appeal. It raises the question: Why not?

But researchers seeking to develop an AIDS vaccine on Monday addressed with skepticism, even an undercurrent of scorn, the announcement by a physicians' group that 50 volunteers are willing to subject themselves to an injection of a live, weakened strain of the virus that causes the disease.

The goal of the International Association of Physicians in AIDS Care would be to speed up the often ponderous scientific process that has historically rested at the root of developing life-saving vaccines.

But, using cautious language even as they said privately the proposal smacks of grandstanding, scientists said such seemingly altruistic human testing, born of frustration, would short-circuit proven safety procedures while offering little of scientific value.

This is because the testing group would be too small to determine whether the vaccine they would receive was ultimately safe. Also, researchers must determine whether such a vaccine, born of live virus, can be reproduced to precise specifications dose after dose.

In any case, said Peggy Johnston, the scientific director of the International AIDS Vaccine Initiative, a nonprofit group established to ensure the development of a safe AIDS vaccine, the proposal raised by the physicians' group in Chicago is for now a case of much ado about nothing: There is no vaccine to test.

It may be an intriguing proposal, and one that may stimulate debate, she said, but at heart the question of an AIDS vaccine remains conceptual.

The group claims there is a vaccine to be tested, the human counterpart of a weakened vaccine tested in monkeys. Dr. Donald Desrosiers of Harvard University first produced a weakened strain of the monkey analog of HIV -- called simian immunodeficiency virus or SIV. Two monkeys immunized with the weakened virus in 1989 are alive and well, despite being exposed to massive doses of SIV.

Desrosiers has subsequently developed a weakened version of the human AIDS virus similar in design to the monkey vaccine. Desrosiers has called for human tests of that vaccine, but other scientists have raised ethical concerns.

Critics fear that the mutated virus may be able to regain its full strength in humans and cause AIDS. HIV, furthermore, is a retrovirus, a class of viruses that is known to cause cancer. Opponents argue that the risks of long-term exposure to even a weakened retrovirus are too high to justify the use of such a vaccine.

The proposed Harvard vaccine is markedly different from other AIDS vaccines now being studied. None of those have the live virus. They all incorporate one or more viral proteins, particularly those found on the surface of HIV, in hopes of stimulating immunity without the risk of infection.

But none of those vaccines provokes a strong immune response. In other diseases, moreover, the best protection has been provided by vaccines containing weakened live viruses, such as those for measles, tuberculosis and polio.

For the moment, however, most researchers believe that tests of a live-virus HIV vaccine are simply too risky.

While dozens of potential products are under scrutiny, none has proved compelling enough for a large-scale trial, in which tens of thousands of high-risk individuals would be studied to determine whether a vaccine actually protects them against infection.