(1937-) US scientist credited with identifying the virus responsible for AIDS. Gallo discovered the virus, now known as human immunodeficiency virus (HIV), in 1984; the French scientist Luc Montagnier (1932– ) of the Pasteur Institute, Paris, discovered the virus, independently, in 1983. The sample in which Gallo discovered the virus was supplied by Montagnier, and it has been alleged that this may have been contaminated by specimens of the virus isolated by Montagnier a few months earlier.