LIKE many other people, I was disappointed to learn about the failure of the clinical trials of the first potential AIDS vaccine.

Disappointing as this was, it should not, however, be a surprise. For while medical research continues to use rats, beagles, guinea pigs and any other species it chooses to test drugs and vaccines for humans, we will continue to get disappointments like this.

Precious time and money are being wasted in this futile endeavour when they could be directed towards far more fruitful avenues of research.

The reason for this failure, and countless others, is quite simple. Animals are not just furry little people. Every species is unique and has a unique physiology and metabolism. You cannot test a drug on a rat and expect it to do the same thing to a human.

Take the drug penicillin, for example. We are very lucky it wasn't tested on guinea pigs before it was given to humans because it kills guinea pigs.

Of course animals and humans share many similarities, but there are great differences at cellular level and genetic level, and it is here that most diseases occur. Even our closest living relative, the chimpanzee, differs significantly from us.

Scientists should realise that the only appropriate subject for the study of human disease is humans. I'm not advocating experiments on people but rather on human tissue and organs.

There are already extremely sophisticated techniques for testing drugs and other chemicals using tissue cultures.

The only people who benefit from animal experiments are the scientists who build rewarding careers from them, the people who build the cages, those who breed the animals and the pharmaceutical companies .

Animal experiments are not a case of choosing between animals and people. Vivisection kills people and animals and we should all be angry at our taxes being wasted in this way in the hope of finding a cure for any disease. We should demand proper science.

Keith Richardson, Norfolk Street, Lancaster.