Michael Hopkin in Nature:
Devastating epidemics that swept Europe during the Middle Ages seem to have had an unexpected benefit – leaving 10% of today’s Europeans resistant to HIV infection.
But epidemics of which disease? Researchers claimed this week that plague helped boost our immunity to HIV, but rival teams are arguing that the credit should go to smallpox.
What is clear is that something has boosted the prevalence of a mutation that helps protect against the virus. The mutation, which affects a protein called CCR5 on the surface of white blood cells, prevents HIV from entering these cells and damaging the immune system.