Mice gene hailed as HIV breakthrough

A gene that protects mice from their equivalent of HIV infection has been discovered by British scientists. The discovery has raised the tantalising possibility of a similar gene being present in humans. However, while scientists say this is unlikely, they agree that the discovery reveals new mechanisms for tackling HIV infection.

Scientists from the National Institute for Medical Research have discovered that mice possessing the gene Fv1 are protected against viruses known as retroviruses. In humans, retroviruses cause Aids and certain cancers.

They contain genetic material known as RNA rather than the more common DNA. They earn their name from their activities after they have landed on a healthy living cell and injected their contents into it. Their RNA converts into DNA which then twists itself up with the host cell's DNA - and then the virus commandeers the cell.

The scientists have discovered that Fv1 (the Friend virus susceptibility gene) blocks this process just before the virus DNA merges with the host's genetic material.

Virologist Jonathan Stoye said that his group had looked for the same gene in humans but had not found it. "But whether other genes with similar activity exist in humans we do not know."

In 1991, evidence was put forward that a group of humans is resistant to HIV in thesame way that Fv1 confers resistance in mice. But the evidence has not been replicated.

Dr Stoye said that his discovery suggested a new mechanism for tackling human retroviruses such as HIV. It might also be possible to tinker with the mouse gene so that it recognises retroviruses other than mouse retroviruses and then to use it in humans.

Other attempts to block HIV have tackled it at an earlier stage in its cycle. The drug AZT, for example, stops the enzyme which converts the retrovirus's RNA into DNA.