That's What You Call a Double Whammy

A recent article in Nature News describes how Leonid Margulis was trying to grow HIV in tonsil tissue infected with herpes, but he couldn't sustain the HIV infection. (Co-infection seems to accelerate HIV progression in people.)  This strain of herpes (HHV-6) blocks the CCR5 receptors that HIV uses to enter cells -- exerting a selective pressure on HIV that makes it more virulent. "These results emphasize the importance of doing experiments under conditions that closely resemble real world cases, rather than in sterile lab cultures," blogs John Dennehy (aka the Evilutionary Biologist).