Scientists are hopeful that a cocktail of two drugs already used to treat HIV infection may prevent the spread of the virus.

Thomas Folks, head of the HIV research lab at the U.S. Center for Disease Control and Prevention says, "This is the first thing I've seen that I think could have a prevention impact."

He continues, "If it works, it could be distributed quickly and could blunt the epidemic."

The drugs are tenofovir (Viread) and emtricitabine, or FTC (Emtriva), sold in combination as Truvada by Gilead Sciences.