Creating HIV-Resistant Mutant Humans

It was discovered several years ago that some people who are resistant to HIV have a mutation in the genes that code for their T cells. (T cells are the immune system cells that are the main target of HIV infection.) HIV gets into T cells by latching onto a protein called CCR5, and people with a certain form of the CCR5 gene are nearly immune to HIV because it can't latch onto the mutant protein.

Today researchers have published a study in which they used commercial gene splicing technology -- enzymes called zinc finger nucleases -- to put the mutant CCR5 gene into the T cells of 12 subjects who are infected with the virus. They then stopped the anti-viral therapy of six of the patients for 12 weeks. In five of the patients, HIV returned, but much more slowly than it normally does when the drugs are stopped. In the sixth patient, HIV did not return at all. He turned out to already be carrying a single, recessive copy of the mutant CCR5 gene. There were no major side effects in any of the patients.

This is certainly encouraging for a first attempt, but obviously there is a long way to go before this could be an effective therapy against HIV. More intriguing is the interaction between  the genetic therapy and the genome of the sixth patient, the one who already had a single copy of the mutant gene. Scientists have long been excited by the possibility of personalizing medical treatments according to the genome of the patient, but until now that has been all hype and hope.