Researches have long thought that acyclovir (Zovirax), a drug to treat herpes (HSV-2), might have anti-HIV powers. In September, researchers at the National Institutes of Health said they had found a clue to explain the link—and it's not, as one theory had suggested, because suppressing HSV lowers immune-system inflammation (thus suppressing production of CD4 cells for HIV to attack).

Instead, the process takes place within cells inhabited by both HIV and herpes. There, acyclovir and herpes bind together in a way that allows the drug to attack HIV. The researchers reconstructed acyclovir so that it could do the same even in cells that harbored only HIV, not herpes.

If this test tube performance can be repeated in humans, the race will be on to get a reformulated, HIV-fighting acyclovir approved. “We are starting a pilot trial to test the hypothesis,” senior researcher Leonid Margolis, PhD, told POZ. Margolis believes it will work and that a pill can be developed, though he cautions, “It will require years and years.” Once available, it could be useful in places where few choices exist for people who no longer get results from available HIV meds. Another benefit? Acyclovir is far less expensive than most HIV meds.