NEW YORK-A chemokine-receptor gene may explain why some people seem HIV-proof.
A team here reported that it’s found an altered CKR5 gene in two unrelated men who remained HIV-negative despite hundreds of potential exposures to HIV during unsafe sex. CKR5 is the recently found cell-surface receptor on T cells and macrophages that HIV needs to fuse with cell membranes.
Dr. Nathaniel Landau’s team at the Aaron Diamond AIDS Research Center showed that the two men had the same deletion of 32 base pairs on their CKR5 gene. Both are healthy.
The men had two copies of the gene, the team reported in Cell. A sample of 23 more seronegatives with high exposure showed some heterozygotes. A look at 400 random DNA samples, 20% heterozygous, also revealed four more homozygotes. All were Caucasians.
In a Nature study, Penn’s Dr. Robert Doms and Belgian colleagues independently reported a third case of the altered gene in another homozygote. Unlike the New York men, his exposure risk wasn’t high, but his cells in culture proved impervious to HIV.
In stored samples, single copies were in 20% of 700 healthy Caucasians but in a smaller proportion of 723 HIV-positives. About 1% of healthy subjects were homozygotes, vs. no HIV-positives. The alteration seems specific for Caucasians.
Both groups said the key to their findings is that people can have an altered CKR5 without ill effects, and a designer drug to block the gene, says Dr. Doms, might foil HIV with little fallout. NIH’s Dr. Anthony Fauci says it’s far too early to think about a CKR5 screening test, lacking certainty that homozygotes are absolutely protected or heterozygotes are protected at all.
NEW YORK-A chemokine-receptor gene may explain why some people seem HIV-proof.
