British scientists have discovered an important clue to the origins of the AIDS epidemic. It is hoped that the discovery will help in providing new ways to treat the disease.

The research team at the Medical Research Council’s National Institute for Medical Research found crucial differences in a gene found in rhesus monkeys that could prevent HIV infection and explain why they are immune to infection while humans are not.

The difference suggest that HIV would not have developed in humans if we had had this strain of gene and indicate that only a single change to the gene is required to stop the spread of the virus in humans.

"This discovery has significant implications for the development of effective gene therapy to combat AIDSs,” said Dr Jonathan Stoye, who led research team.

"In theory, it should be possible to take cells from an HIV-infected individual, make them resistant to HIV infection with the modified gene, and re-introduce them to the patient. These cells could then block progression to Aids,” he said.

"Alternatively, we could seek drugs that activate the human gene against HIV."

Christopher Gadd, editor of HIV & AIDS Treatments Directory, told the BBC News website: "What is particularly exciting is that the researchers have identified that changing just one amino acid 'building block' in one protein can switch a cell from susceptible to insusceptible to long-term HIV infection.

"However, it is important to stress that any therapeutic benefits that may arise from this research are unlikely to be felt for many years.

"This type of gene therapy would involve removing white blood cells from patients, cloning them, and altering their genetic make-up before reintroducing them to the patient on an individual-by-individual basis.

"Although it is theoretically possible, this approach is unlikely to be practical or cost-effective with currently available technologies."

According to the latest UNAIDS figures 39.4 million people worldwide are living with HIV/Aids.

The findings pf the research will be published in the latest edition of the Current Biology magazine.