Two new studies found that years after powerful drugs have virtually eliminated the AIDS virus from the bloodstream and forced it into hiding in the body, it can continue to infect new cells. The finding underscores just how difficult it may be to cure AIDS. Previous studies have shown that the AIDS virus hides in certain places in the body, including certain immune cells and organs such as the brain, testicles and eyes that are not easily penetrated by drugs. But doctors hoped that continued use of AIDS drugs would keep tha virus in a dormant state and eventually kill off all traces of the infection. The studies in Thursday's New England Journal of Medicine show that HIV continues to infect new cells despite the use of AIDS drugs.