Peter Duesberg does not look like a deluded crank as he sits over breakfast in a little house in a pleasant Californian university campus and states categorically that the world has got it completely and tragically wrong about Aids.

Witty, grey-haired and wiry for his 55 years, Professor Duesberg, a German by birth, speaks with the blithe self-assurance of a dissident who has seen the light, endured banishment for his views and now senses vindication around the corner. Aids, according to his controversial thesis, is not an infectious disease, it has nothing to do with the HIV virus and the thousands of healthy people are being killed by taking the anti-Aids drug AZT.

The sharp increase in the 1980s of the diverse, long-standing diseases lumped together as Aids stems, he says, from damage to the immune system inflicted by excessive use of recreational drugs, particularly the nitrites or "poppers" and other psychoactive (mood-altering) drugs favoured by homosexuals. It's so embarrassingly clear that I don't see how someone can argue around it, "he says. The fallacy of the Aids virus will turn out to be "the most colossal mistake in medical history'.

At this stage the leaders of the "Aids establishment" - government-funded researchers, the drug companies and militant homosexuals organisations - would like to read and turn the page. Professor Duesberg is publicity hungry maniac, they say. He is a flat-earther, but his his ideas are more than loony, they say. They are dangerous because they sow doubts about such cardinal tenets as the need to practise safe sex and support the campaign for "Aids awareness".

He has already had enough publicity, they feel, thanks to some conservative American magazines which have been quick to give credence to doctrines which are not just politically incorrect, but downright heretical.

On the lush, hillside campus of Berkeley, the academic grove where he is a professor of molecular and cell biology, some of his students call him "crazy old Duesberg" and Dr. Robert Gallo, the American who is credited as the co-discoverer of the HIV virus and a former friend, was quoted saying that he cannot discuss the Duesberg hypothesis "without shrieking".

Dr Gallo would probably not have to do so at all, were it not for the fact that the professor has distinguished credentials. He is a world-leading virologist and did pioneering work mapping the structure of retroviruses, of which HIV is one; he is a member of the American Academy of Sciences and, until the controversy caused him to lose it, he held a $ 350.000 per year "Outstanding Investigator" grand from the National Institutes of Health (NIH), the American government body which oversees the expenditure of billions of dollars on Aids research. The grant, awarded for the pursuit of his cancer research, is intended to enable brilliant researchers to "venture into new territory "and "ask creative questions".

Professor Duesberg deserves his ostracism, say his opponents. Michael Fumento, who earned the wrath of the homosexual community for his book, The Myth of Heterosexual Aids, which charged the "Aids establishment" with exaggerating the risks of the disease for heterosexuals in order to build political pressure for more funding, has publicly accused Professor Duesberg of his bad faith, saying in this month's American Spectator. "It's a big game with this guy and I don't think this is very funny."

Yet, far from fading under four years of ridicule, Professor Duesberg is enjoying something akin to a glimmer of vindication. Over the past year or so, some mainstream Aids researchers have been coming round the notion that the HIV virus may only be a part of the cause of Aids. The disease seems to require the presence of a "co-factor", some micro-organism they believe, which works with it to trigger the destruction of the immune system, allowing the body to be invaded by the Aids diseases.

A turning of the tide may have come, Professor Duesberg believes, with the change of heart of Luc Montagnier of Pasteur Institute, the man who first identified the HIV virus. Dr Montagnier now subscribes to the idea that HIV is not alone responsible for Aids and he is due to attend an alternative Aids symposium in Amsterdam this week along with others from the 50-member Group for Scientific Reappraisal of the HIV/Aids hypothesis.

After years in which no major scientific journal has given Professor Duesberg any platform, an article in Britain's Nature last September, written by its editor John Maddox, suggested, though still sceptical, that there might be a grain of sense in his theories. Any mention of them in print, however, still elicits fury from those Professor Duesberg sees as the priests of the official Aids "church".

My interview with him was at the home of one of his three daughters, a biology undergraduate at the University of California at Riverside, about 60 miles east of Los Angles.

His daughter had invited him to give a seminar there; fellow students suggested they should not tell their professors for fear of a veto.

In dismissing HIV as irrelevant and calling Aids non-viral, Professor Duesberg is still far beyond the consensus of the "co-factor "school. But, he says, the fact that eminent scientists have now opened this door is an admission of defeat.

"The idea of co-factors is a euphemism" he says in the German accent which has not left him since he came to America in 1964. "It is very difficult to say you were wrong when you are spending three billion dollars a year and 180.000 people have been given AZT. They're trapped in so many ways."

The grounds for the professor's break with orthodoxy are well enough known, thanks to the publicity over the past year or so. His doubts began within a couple of years of the official acceptance, in 1984, of the theory that the HIV virus triggered the immune system disorder which allowed the development of pneumonia's, cancers, dementia and other "opportunistic" diseases.

There were many anomalies which seemed to contradict the notion of a virus epidemic. Professor Duesberg says. Among these were the fact that people have died of "Aids" with no trace of HIV antibodies in their system, according to the professor, this has received some corroboration with evidence that some patients who suffer from Kaposie's sarcoma, the previously rare skin cancer which suddenly reappeared with homosexual Aids patients, have not been HIV positive.

The most glaring failure of Aids to follow the epidemiological norm, Professor Duesberg claims, is the restriction of the condition in America and Europe almost entirely within the high-risk groups of male homosexuals and drug users. The disease has failed to explode, as widely predicted, into the general population, including heterosexual women and teenagers; at the same time, venereal diseases have soared, indicating no drop in unprotected sex, he says. According to the latest figures from the Centres of Disease Control, the American government's main monitoring body, 86 per cent of Aids patients are homosexual or intravenous drug users, or both.

Then there is the question of why the HIV infection level in the American population has remained around the million mark, according to a consensus of authorities. This would not be consistent with a viral epidemic, say the professor and his supporters. A study in the United States forces between 1985 and 1989 showed as many women as men to have been carrying HIV antibodies, yet men develop Aids four times as much. In Africa, Professor Duesberg says, about 15 per cent of the population is estimated by the World Health Organisation to carry the HIV virus, but only 41.000 cases of Aids have been reported. Another enigma comes from the huge difference between the African and North American versions of Aids. Professor Duesberg suspects that diseases long endemic to Africa, such as slim disease and tuberculosis, are attributed to Aids and HIV though there is no connection.

Specifically in Professor Duesberg territory, no virus has ever behaved in the way HIV is supposed, by its advocates, to do. It is present in only tiny quantities, it triggers an antibody reaction which indicates that it has been neutralised and yet it is said to become active years, or decades later. "There's absolutely no precedent anywhere in biology, or even microbiology, that a microbe causes a disease only after it is neutralised...The Aids virus remains dormant. Even among those dying of Aids. It makes no sense." Professor Duesberg says. His critics say viruses have been known to remain dormant and than re-activate despite the presence of antibodies which suggest they were "conquered". The virus, says the professor, is just one of many that have been around for centuries but which have only been detected since the development of highly sensitive tests, rather as new stars were "discovered" with the improvement of telescopes. The fact that HIV is actively present in one out of every 10.000 T-cells shows, he says, the nonsense of claiming that they invade the body. "To take over, you 've got to get in there and invade a large number of cells. It's like you invade a country with soldiers. You're not going to claim you have captured the US by invading Riverside with 50 Chicanos... They have hyped up HIV into this super-rapist but in reality the damn thing can hardly get an erection."

Nothing demonstrates the failure of the virus-Aids hypothesis better than its results, he says. It has saved not one life, not predicted the spread of Aids correctly, and not led to any useful medication or vaccine. AZT is the drug of choice for Aids patients and is acknowledged to cause side-effects such as anaemia. But the evidence of controlled trials is that it prolongs life. Professor Duesberg insists that the adoption of AZT is one of the scandals of the Aids story. The drug is a "DNA terminator", that is, it has an adverse effect on the chemistry necessary for life and destroys the immune system. It's as if you used a neutron bomb to try to kill a harmless rabbit."

AZT was approved in the United States in 1987 in a leap of faith after some highly flawed research, Professor Duesberg and his supporters believe. Using another of the arguments that outrages his opponents, the professor says the use of AZT obscures the evidence because the drug itself induces Aids diseases. He believes that if Magic Johnson, the celebrity basketball player who is HIV positive, develops Aids, it will have been caused by AZT not HIV. He says he has tried to warn Johnson, but does not know if his message has got through.

The same may apply to Arthur Ashe, the former tennis champion, who recently announced that he has been HIV positive for three years. According to Professor Duesberg, if Ashe does have an immune system disorder, it is likely to have been acquired during the two big heart operations he underwent, not from HIV infection during blood transfusions. He says procedures that are traumatic to the body, such as surgical operations or blood transfusions, have been recognised to play a role in weakening the immune system.

He believes that Kimberly Bergalis, the young Florida woman who was said to have been infected by her dentist, was diagnosed as suffering from Aids because she had a yeast infection and was then found to be HIV positive. "The most serious consequence for her was that she was treated with AZT." Professor Duesberg says. By accepting the HIV hypothesis, the Aids establishment had locked itself into a closed logical loop, says the professor. Aids is defined as a syndrome of 15 old diseases in the presence of HIV, a standard criteria for an infectious pathogen, or disease causing agent. So if someone dies of an Aids-type condition without HIV, it will not be listed as Aids. Among the diseases are several such as Kaposi's sarcoma, lymphoma and wasting disease and dementia, which have no association with microbes or viruses. Professor Duesberg is also scathing about the repeated revisions of the estimated latency period, as the HIV positive population has, he says, shown no sign of succumbing to Aids diseases faster than the non-HIV population, a claim that is vigorously challenged by the orthodox. At first, the experts talked of months from infection. Now they say 50 per cent are expected to contract the disease within a decade. "It's like moving the goal posts, or in the middle of Wimbledon, you keep raising the net because you are losing" says the professor with one of the metaphors that make him eminently quotable and infuriate the critics who accuse him of playing to the media.

The Aids community has answers for all the professor's objections, but he throws them back with something approaching glee, warning the laymen not to be intimidated by their jargon".

He says it all reminds him of his Catholic childhood in Germany when the church had a similar reaction to anyone who challenged the faith. Rather than denounce him and banish him they should just allow him to state his case in a serious forum and then prove him wrong, he says.

It would, for example, he says, be easy to carry out a controlled study of say, 100 haemophiliacs to see if those with HIV succumbed to diseases any faster than those without. There is no evidence, the professor says, that haemophiliacs are dying more from immune system-triggered diseases than they were before. Large transfusions of blood were long known to destabilise the immune system, as malnutrition has been.

The whole Aids establishment, which spends three billion dollars a year, would prefer to tune him out for political reasons, he says. "Aids more than any other disease has been politically correct from the very beginning. It was linked to gay liberation. Gays were not to be blamed for anything. A viral cause is God-given, but a man-made cause is not politically correct. Of course there's patriotism in it too. The NIH is a colossal institution, and it had to show something for its money to the president."

Though some New York homosexual groups have warmed to Professor Duesberg's ideas, the majority are ferociously opposes to his theory that the surge in Aids-type diseases is a direct consequence of the abuse to the human system from self-administration of toxic drugs such as heroin, nitrites, cocaine, amphetamines and the rest of the armoury of the modern age. The link to homosexuality sprang from the explosion of drug consumption in the wild free-for-all of gay liberation in the 1970s, he says. Yet no studies have investigated the long-term effects of psychoactive drugs on animals comparable with the time periods and dosages used by Aids patients. It's very testable what I'm saying. Why don't we test street drugs and see what it does to the immune system?"

This is how Professor Duesberg arrives at his conclusion that safe sex and clean needles in themselves do nothing to halt the spread of Aids, a view that incites apoplexy among Aids workers. The screening of blood for HIV antibodies is itself a "toxic" practice, says the professor, because a positive outcome amounts to a psychological death sentence. The only way to prevent Aids, he says, is to educate people out of abusing drugs.

Now, with the last of his NIH funds drying up, Professor Duesberg has succeeded in lodging an appeal against the suspension of the grant and he believes he may land fresh official funding for work in his cramped laboratory on the first floor of the Stanley Hall at Berkeley.

It may not take long for history to judge whether he is a brilliant visionary or a dangerous distraction in the pursuit of a remedy to the most mysterious and terrifying disease of this era.*