FILE - In this Feb. 25, 2011 file photo, Jay Johnson speaks during an interview at the University of Pennsylvania. Johnson, who works for Action AIDS, an advocacy and service organization in Philadelphia, had gene therapy treatment for HIV in 2011. Although the virus rebounded when he temporarily went off HIV medicines, tests show his modified blood cells are still multiplying. In 2014 he says, "I was hoping I wouldn't have to stay on medication" but eventually it may no longer be needed, he said. "Hopefully one day I'll be able to say I'm HIV negative again." (AP Photo/Matt Rourke)