Robert Charles Gallo (1937) is an American physician, biologist and academic, known for having discovered the retroviral origin of AIDS in 1982, confirmed the following year by the isolation of HIV type 1 by Luc Montagnier and Françoise Barré-Sinoussi.

Gallo is the director of the Institute of Human Virology at the University of Maryland in Baltimore. In 2005 he was co-founder of "Gallo Profectus Biosciences" which develops and commercializes technologies to reduce mortality caused by viral diseases.

He was born in Waterbury, Connecticut to a family of Italian immigrants. His paternal grandfather, Domenico Gallo, a landowner from Piemonte, emigrated to the United States because of disagreements with his family caused by his marriage to a woman who was not of noble birth. His maternal grandfather, who was from Puglia, also emigrated to America to escape poverty.

His father, Francis Gallo, worked in metallurgy. Unfortunately, the childhood of future Professor Gallo was marked by tragedy, the loss of his younger sister, an event that deeply affected him for the rest of his life but which would later be a source of inspiration for his career choices. In his high school years, Robert Gallo devoted all his time to sports but after fracturing his tailbone and not being able to play for some time, he took to Medicine and began to study it.

He received his B.A. in Biological Sciences from Providence College in 1959; after a few years he also obtained a degree in Medicine and Surgery from Philadelphia Jefferson College in 1963. During his studies, he became interested in research and in 1961 he began working at Harvard where he met Alan Erslev, the one who would introduce him to research. He worked for two years at the University of Chicago, before joining the National Cancer Institute in Bethesda, MD., where he remained for 30 years.

Professor Gallo and his collaborators pioneered the field of human retrovirology, discovering, in 1980, the first human retrovirus, HTLV-1, to be the cause of a particular form of human leukaemia. The following year, the same team discovered the second, HTLV-2, and the third human retrovirus known as HIV, providing the first results that demonstrated that HIV was the cause of AIDS (acquired immunodeficiency syndrome).

Despite the initial lack of interest in the investigation of the deadly virus that was claiming so many lives in Los Angeles and New York, Gallo decided to use, in the summer of 1982, part of the resources of his group of scientists for the study of this infamous new disease that was expanding rapidly and heavily affecting the American public opinion. Studying AIDS patients, Gallo noticed a dramatic drop in white blood cells and began to share the Atlanta Center for Disease Control and Prevention’s (CDC) belief that the disease was caused by a virus.

He carried out several experiments, trying to validate his hypothesis. Although the first experiments were not successful, halfway through 1984 several cultures gave new and interesting results. A French team from the Pasteur Institute in Paris, led by Luc Montagnier, published an article in the Science scientific journal describing a retrovirus called LAV (Lymphadenopathy Associated Virus), isolated from a patient at risk of AIDS. On May 4, 1984, Gallo and his collaborators published four papers in the same journal, trying to prove the link between AIDS and the HLTV virus he had discovered. Gallo received his second Lasker Prize in 1986, "for proving that retroviruses, nowadays known as HIV-1, are the cause of AIDS." He is the only recipient of two Lasker awards.

In 1995, Gallo published a study on chemokines, a class of natural compounds, demonstrating that they were able to block HIV and halt the progression of AIDS. This discovery was heralded by the Science journal as one of the most important scientific breakthroughs. Chemokines play a key role in controlling the progression of HIV infection; they provide better understanding of how the human immune system works against AIDS, directing clinical research on the possible use of a class of drugs to treat HIV.

At the Institute of Human Virology, Gallo's team carried out a scientific research program and provided clinical care for people living with HIV/AIDS, treating more than 4,000 patients in Baltimore and about 200,000 in Africa and the Caribbean. In July 2007, Gallo and his team were awarded a $15 million grant from the Bill and Melinda Gates Foundation to research a preventive vaccine for HIV/AIDS.

In 2008, Montagnier and his colleague Françoise Barré-Sinoussi of the Pasteur Institute, were awarded the Nobel Prize in Physiology or Medicine for their work on the discovery of the HIV virus. Robert Gallo, on the other hand, was left out.

The attribution of responsibility for the discovery of the HIV virus has been notoriously controversial, but today it widely accepted that Robert Gallo and Luc Montagnier, with their respective research groups, have both contributed significantly to such outcome.

In 1987, due to uncertainties related to the discoveries, the French and U.S. governments decided to split the co-discoverers' patent proceeds equally. Montagnier and Gallo resumed their collaboration in 1987. In the November 2002 issue of Science, Gallo and Montagnier published a series of papers, one of them co-authored, in which they acknowledged each other's fundamental role in the discovery of the HIV virus. However, in 2008, the Nobel committee decided not to award Gallo for the discovery of the HIV virus. In fact, the Nobel committee chose to split the physiology prize between the discoveries of HIV and of the papilloma virus, rather than include Gallo in a single prize.

Since 1996, Professor Gallo has served as Director of the Institute of Human Virology and The Homer & Martha Gudelsky Distinguished Professor of Medicine, Microbiology and Immunology at the University of Maryland School of Medicine. He is also currently co-founder and international scientific advisor of the Global Virus Network (GVN).

He has received 35 honorary doctorates from universities in the United States, China, Sweden, Italy, Israel, Peru, Germany, Belgium, Mexico, Argentina, Spain, Ireland, Jamaica and Greece. He is a member of numerous professional and honorary societies, including the US National Academy of Sciences, the Institute of Medicine of the US National Academy of Sciences, the Royal Society of Medicine (Glasgow, Scotland), the Royal Society of Medicine (Brussels, Belgium), the Royal College of Physicians (Ireland) 2007, and the National Inventors Hall of Fame.

He has received numerous important scientific awards and prizes, the most prestigious among which is the American Albert Lasker Prize (awarded twice, in 1982 and 1986), the General Motors Cancer Research Prize (1984), the American Cancer Society Medal of Honor award (1983), the Gairdner Foundation International Award (Canada, 1987), The Japan Prize of Science and Technology (1988), the Paul Ehrlich and Ludwig Darmstaedter Prize (Germany, 1999), the Principe de Asturias Award for Technical and Scientific Research (Spain, 2000), the World Health Award from President Gorbachev (Vienna, 2001), the first Otto Herz Memorial Award for Basic Research on Malignant Processes (Israel, 1982), the Rabbi Shai Shacknai Memorial Price of the Hebrew University (Israel, 1985),  the Birla International Award of the Tata Memorial Center (India, 1986), the Tevere Roma International Award (Italy, 1985), the Harvard Medical School Warren Alpert Foundation Award (1998), the first Israeli prize, the Dan David Award (2009) and the Paul G. Rogers Médical Science Award of the US National Library of Medicine (2010). The Homer & Martha Gudelsky Distinguished Professorship in Medicine, University of Maryland School of Medicine (2013).

According to the Institute for Scientific Information, Professor Gallo was the most quoted scientist in the world and was ranked third in the world for scientific impact for the period between 1983 and 2002. He has published nearly 1,200 articles.