A RARE genetic mutation that protects people against HIV infection also appears to make them more vulnerable to West Nile virus.
The gene for the CCR5 receptor, which is HIV鈥檚 gateway into a cell, has been the focus of much attention in the past decade since it emerged that individuals with two copies of a particular version of the gene appear resistant to attack.
This raised the possibility of blocking the gene artificially, and until now there was no sign that this would be harmful. 鈥�CCR5 seemed to be a good-for-nothing gene,鈥� says Philip Murphy, an immunologist at the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland.
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Then Murphy鈥檚 team found that all their mice carrying two copies of the mutant CCR5 gene died when infected with West Nile disease (The Journal of Experimental Medicine, DOI: 10.1084/jem.20051970).
And when Murphy checked blood samples from 365 people in Arizona and Colorado who had symptoms of West Nile virus, he found that they were five times as likely to have the mutated form of the CCR5 gene as the general population. 鈥�CCR5 has a yin-yang personality,鈥� says Murphy. In its normal form 鈥渋t is good for protecting people from West Nile, but bad in the case of HIV鈥�.
Murphy believes the CCR5 receptor may be involved in recognising West Nile virus and alerting the immune system.
