Françoise Barré-Sinoussi and Luc Montagnier, at the Pasteur Institute in Paris, isolate in 1983, from lymph nodes of a patient with symptoms associated with acquired immunodeficiency syndrome (AIDS) — a disease clinically identified just two years earlier and of then-completely unknown origin — a retrovirus they initially call LAV (lymphadenopathy-associated virus). The team detects reverse transcriptase enzyme activity in the patient's cell culture, characteristic evidence of the presence of a retrovirus — a family of viruses that also includes human T-cell leukemia virus, identified a few years earlier by Robert Gallo's team in the United States. Identification of the virus, later renamed HIV (human immunodeficiency virus), makes it possible within a few years to develop diagnostic tests to detect infection in blood, essential for protecting blood transfusion supplies, and opens the way toward the development of antiretroviral drugs specifically targeting the virus's enzymes — including reverse transcriptase, discovered a decade earlier by Baltimore and Temin — which would progressively transform AIDS from a terminal illness into a manageable chronic condition over subsequent decades.