For a cause

Healthy people in the US are lending their bodies to help researchers develop a vaccine for AIDS

Published: Wednesday 15 October 1997

in st Louis, Missouri, usa , hundreds of healthy people are leasing their bodies to medical research and contributing to the development of a vaccine for aids . They are receiving injections containing canarypox viruses that cause disease in birds but are harmless to humans. After being genetically-engineered, the viruses envelope three extra genes that are normally found only in hiv , the virus that causes aids . In a few weeks time, the bodies of the volunteers who do not have aids will start behaving as if they had the virus. Researchers hope that the introduction of aids -like characteristics to the volunteers' bodies would lead to the creation of antibodies that can fight off a real infection.

The health risks involved are considerable. For one, any experimental vaccine that is effective will leave the volunteers' replete with hiv antibodies. This implies that they would test positive on any aids test in the future whether they have the virus or not. Researchers cannot be sure if the engineered bird virus would not make the volunteers ill. Moreover, as some studies on animals suggest, aids vaccines can sometimes speed up the progression of the disease in people who eventually become infected.

The struggle to develop a vaccine for aids has never been as intense as it is at present. Though some new drugs and therapies have been successful in curbing the disease to an extant, the benefits are only temporary. Also, they are quite expensive and unavailable in developing countries where 95 per cent of new cases of aids are being reported. "We will never end this epidemic unless we have a vaccine," says Sandra Thurman, chairperson of the White House Office of National aids Policy.

But developing a vaccine has also never seemed more difficult. Researchers have endured so many disappointments in the last few years that it is being viewed as a lost battle. The risks to volunteers are considerable and the testing processes laborious. Also, hiv is like no other virus as it infects the very immune system cells that form the bodies' line of defence -- the cells that vaccines are supposed to assist.

The virus has an uncanny knack of mutation that makes it a constantly moving target, says Robert Belshe, vaccine researcher at the St Louis University who heads the aids vaccine evaluation group, a network of research sites in six us cities funded by the National Intitutes of Heath, Bethesda. Moreover, hiv does not infect animals such as mice or monkeys that are generally used in biological research to test vaccines. It does infect chimpanzees but they do not become sick for at least ten years.

This leaves researchers with the only one option -- human volunteers. The response in St Louis is very encouraging, as are the salvaged bits of information from previous experiments that failed. Researchers are optimistic -- though cautious -- and say that they are beginning to get an idea of what a successful aids vaccine would look like. "It is still not going to be easy. But the idea that it is impossible is gone," says Patricia Fast, associate director of the vaccine and prevention research programme of the National Institute for Allergy and Infectious Diseases, usa .

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