believed to cause acquired immune deficiency syndrome (AIDS)
in humans. Transmitted through contact
with body fluids such as blood, breast milk, cervical secretions, saliva, and semen, it weakens the body's immune system
and causes infection that has a long incubation period
(typically 10 years). Discovered independently by the French researcher Luc Montagnier at the Pasteur Institute in 1983, and by the US researcher Robert Gallo at Maryland National Cancer
Institute in 1984.