When an outbreak of sexually-transmitted human immunodeficiency virus, or HIV, hit the United States in the early 1980s, not much was known about the virus or how it spread. But scientists, researchers and volunteers at Pitt have been working for almost four decades to try and change that.

HIV/AIDS timeline: key events and breakthroughs; new milestone in HIV research: an experimental HIV vaccine has for the first time cut the risk of infection by nearly a third.