WASHINGTON (AP) -- A prominent immunologist was named Wednesday to head the National Institutes of Health's AIDS research programs. Dr. William Paul, best known for his discovery of a key immune system molecule that is attacked by the AIDS virus, will head the NIH's Office of AIDS Research. Congress, under pressure from AIDS activists, last spring reorganized the office, giving it more personnel and power to direct federally funded research into the viral plague. As director of OAR, Paul will coordinate NIH's $1.3 billion AIDS research budget, plan AIDS policy with scientists, activists and lawmakers, and oversee federally funded research at some 21 NIH institutes. "I am confident that Dr. Paul has the scientific acumen and leadership qualities needed to re-evaluate and shape our approach to AIDS and ensure we are doing all we can to combat it," said NIH Director Dr. Harold Varmus, who appointed Paul on Wednesday. AIDS activists praised Paul. His appointment is "the strongest of signals from the Clinton administration and NIH leadership that AIDS research is a top priority," said Derek Hodel of the AIDS Action Council. Paul currently is immunology chief at the National Institute of Allergy and Infectious Diseases, the NIH arm that has shouldered the bulk of the agency's AIDS research. He is best known for the discovery of interleukin-4, an immune-activating molecule that is defective in patients with HIV, the AIDS virus that attacks key immune cells. NIH is testing various forms of interleukin to see if it will improve immune system activity.