Who is credited with identifying HIV as the cause of AIDS?

Robert Gallo is credited with identifying HIV as the virus that causes AIDS. In 1984, Gallo and researchers at the U.S. National Cancer Institute published evidence linking a retrovirus—then called HTLV-III—to AIDS and developed a method for detecting it in blood.

The history is more complicated than a single-name answer suggests. In 1983, a team at France's Pasteur Institute, led by Luc Montagnier and including Françoise Barré-Sinoussi, isolated a related virus from a patient with lymphadenopathy. That virus was called LAV. Gallo's group independently identified what it called HTLV-III, demonstrated its relationship to AIDS and produced the research that enabled a practical blood test.

The two isolates were later recognized as the same virus, and the name human immunodeficiency virus, or HIV, was adopted in 1986. Because Montagnier and Barré-Sinoussi are credited with identifying the virus, while Gallo is especially credited with demonstrating that it causes AIDS, some historical accounts describe the discovery as shared. The wording of this question specifically points to Gallo's role in establishing causation.