Back in the early 1990s, Nathaniel Landau was a young virologist just starting his career in HIV research. But he and his colleagues were already on the verge of a landmark breakthrough. Several labs around the world were hot on his team's tail."We were sleeping in the lab, just to keep the work going day and night because there were many labs all racing against each other," Landau says. "Of course, we wanted to be the first to do it. We were totally stressed out."Other scientists had identified groups of people who appeared to be completely resistant to HIV. "People...