HIV-resistant gene is not unusual

Genetic resistance to HIV, the virus that causes Aids, may be more common than has been supposed. American scientists report today that they have discovered a gene variation found in about 30 per cent of all races which confers resistance - though not immunity - to HIV.

The gene, which affects the shape of a chemical receptor on human cells, called a chemokine, extends the period that HIV-positive people can survive without developing the immune system collapse that occurs in Aids. Those with the mutation can survive to up to 16 years, rather than the two or three years typical in HIV-infected people who have so far died of Aids.

Reporting in the journal Science, a team led from the National Cancer Institute in Maryland found a relatively common mutation in a gene called CCR2, which makes one of the cell receptors that the virus needs, in order to become established and infect the body. HIV is a "retrovirus", and works by insinuating itself into the cell's reproductive machinery, so that future copies of the cell also make HIV.

Scientists discovered last year that some people are effectively immune to HIV because they have a mutation in another chemokine, called CCR5. That occurs in roughly 1 per cent of caucasians, but apparently not in other ethnic groups.

The CCR2 mutation is found in all ethnic groups tested, including Hispanics, blacks and whites. The new finding could be significant for developing therapies in future.