'It is absolute nonsense,' says HIV research pioneer Abraham Karpas. 'They don't understand the biology of the virus. We will cure every cancer before we find a cure for HIV.'

A decade after the development of a therapeutic drug cocktail, which transformed AIDS from a killer infection to a chronic disease, doctors said yesterday that they may have made the next big breakthrough.

AIDS is unique among infectious diseases because even after treatment with a cocktail of powerful drugs, "latent" virus remains hidden in the body's DNA and erupts as soon as treatment stops.

The scientists found that combining a cheap drug called valproic acid with the existing therapeutic cocktail, the level of "latent" HIV fell dramatically. They claim they may be able to eliminate the latent HIV altogether, curing the disease.

New Approach Suggested

David Margolis, who led the research team at the University of North Carolina, said, "Our findings suggest that eradication of established HIV infection might be achieved in a staged approach. This finding, though not definitive, suggests that new approaches will allow the cure of HIV in the future.

"I would like to set scientists on the way to looking for a means to eradicate the virus. That is why I am excited about this. But I don't expect it to happen soon. In the meantime prevention has to be the key message."

The US researchers describe their research as a "proof of concept" study which involved testing four patients who had been on long-term treatment with the standard drug cocktail. They say it opens up new research possibilities but it will be many years before a new treatment results.

Controversial Results

The claims, published in The Lancet, had some scientists hailing a breakthrough as others warned against talk of a cure. One dismissed the researchers' claims altogether.

Jean Pierre Routy, of McGill University in Canada, said in a Lancet commentary that the finding "merits further urgent study."

Speaking to The Independent, he said: "It is a milestone. It paves the way to a possible cure. Last week we thought it was impossible (to eradicate the virus). Now for the first time this finding shows it could be workable."

Robin Weiss, professor of virology and an expert on HIV at University College London said, "This is a potentially exciting advance, but any talk of 'curing' infection is premature if not reckless."

The researchers' optimism was challenged by Abraham Karpas, of the University of Cambridge, the first person to isolate the HIV virus in the UK, who said, "It is absolute nonsense. They don't understand the biology of the virus. We will cure every cancer before we find a cure for HIV. The only way to defeat this disease so far is to prevent infection."

Team Enhances Cocktail

HIV has presented science with one of its greatest challenges because of its ability to infiltrate the DNA in the cell, the genetic code, from which new virus can be generated.

Active virus is destroyed by the drug cocktail known as highly active antiretroviral therapy (Haart), now the standard treatment for HIV. But the latent virus remains hidden and scientists have believed that it was impossible selectively to kill the infected cells or to flush out the virus hidden in them.

The University of North Carolina team intensified the effect of Haart with an extra drug and then gave the patients valproic acid, used to treat epilepsy since the 1960s, twice a day for three months. In three of the patients there was a 75 per cent reduction in latent HIV infection and a smaller reduction in the fourth patient. Valproic acid is a gene regulator whose mechanism of action is unclear.