Monkey Dies In AIDS Vaccine Test.(Brief Article)

2002 FEB 6 - (NewsRx.com & NewsRx.net) -- In a study that illustrates how cunning a foe AIDS is, a monkey that was given an experimental AIDS vaccine died after the virus changed just one of its genes.

HIV, which causes AIDS, already is known to mutate and grow impervious to standard AIDS drugs in at least half of all Americans being treated for the infection.

Now researchers have seen a similar outcome with an experimental vaccine that tries to stop the virus from multiplying. The mutation occurred in one of eight vaccinated rhesus monkeys in a Harvard experiment.

Scientists who reviewed the results described the monkey's death as "more disappointing than surprising.'' It does not mean that AIDS vaccines are doomed to fail, they said, but illustrates how the virus will not be easily defeated or even contained anytime soon.

"It is sobering to find that a single-point mutation within the virus can initiate a cascade of events resulting in a clinical vaccine failure and death,'' said Dan H. Barouch, a clinical fellow at Harvard Medical School and lead author of the study. The findings were published in the January 16, 2002, issue of the journal Nature.

More than one dozen experimental vaccines using different genetic strategies have been tested in various laboratories. Some have been successful for more than two years. Unlike a flu shot, AIDS vaccines do not actually prevent infection by the invading virus. That is because HIV comes in many strains and changes rapidly.

Instead, the AIDS vaccines work to hold HIV infection in check. The vaccines are made with genes that carry the code for proteins in the virus. When the immune system sees these codes, it learns to stimulate production of virus-fighting cells known as killer T cells.