Hilary Koprowski was a Polish virologist and immunologist. He was the first scientist to produce attenuated poliovirus and to conduct large-scale clinical research studies of an oral polio vaccine. His vaccine was used to immunize millions of children during trials in the Belgian Congo and Poland. He was the director of the Wistar Institute of Anatomy and Biology from 1957 to 1991 where he developed an improved rabies vaccine and pioneered the usage of monoclonal antibodies for cancer diagnosis and treatment. He was a professor of microbiology and immunology at the University of Pennsylvania and director of the Center of Neurovirology and Biotechnology Foundation Laboratories at Thomas Jefferson University. He co-founded the biotechnology firm Centocor in 1979.