Oh, that little mind-game of a virus. Just when it seemed that a structured treatment interruption (STI) might give the immune system a chance to deck the virus on its own, we discover that the minute HIV rebounds in someone off HAART, it heads straight for the very HIV-specific CD4 cells that are the first line of defense against the virus. That's the take-home from new work by the NIH Vaccine Research Center's Daniel Douek, MD, PhD, and colleagues, who reported in a recent issue of Nature that, though the virus is an equal-opportunity attacker of CD4 cells when it rebounds, it gives special treatment to those specifically charged with bashing HIV. In other words, the more CD4 cells you made while on meds, the more for the bugger to infect when you go off. So are STIs RIP? Not at all, sayeth Douek: Short-term -- one-week-on, one-week-off -- drug breaks can still cut side effects, toxicity and costs in half while keeping the virus from taking off. Moral of the story? As Douek told Reuters Health: "We must not tarnish all STIs with the same brush."