In memoriam:Hilary Koprowski, 1916-2013.

Hilary Koprowski, who died this year at the age of 96, was an extraordinary person. He excelled as an innovative scientist, a director of a research institute, a classical pianist, a composer of music, a connoisseur of art, and a polyglot world traveler. Born in Warsaw, Poland, where he obtained a medical degree, the Nazi invasion forced him and his wife, Irena, to flee to Italy, where he studied piano at the Accademia Nazionale di Santa Cecilia in Rome. During the Second World War, he managed to emigrate to Brazil, where he became a research assistant in the Rockefeller Foundation Laboratories. There, his work on yellow fever and several arboviruses so impressed the senior staff that a position was found for him at the Lederle Laboratories in Pearl River, New York. At Lederle, he began work leading to improved rabies vaccines and on attenuation of polio virus, the work for which he will be most remembered. In the early 1950s, there was pessimism about the development of a polio vaccine subsequent to disastrous clinical trials of two experimental vaccines. Koprowski set out to attenuate the virus through adaptation to mouse brain. Starting with what later was identified as a type 2 strain, he achieved attenuation of neurovirulence in monkeys. After ingesting the orally administered vaccine himself, he arranged to vaccinate 20 mentally disabled children in collaboration with the physician in charge of the institution in which they resided, although it is said that his superiors at Lederle were unaware of this step. The ethical justification was the fear of poliovirus entering the institution, a common occurrence at the time. Although this first trial showed safety and immunogenicity of the strain, the presentation of the results at a later scientific meeting was greeted with shock because of the audacity of the work (1). In the mid-1950s, cell culture became available, and Koprowski and Albert Sabin separately began to attenuate polioviruses by passage in monkey kidney cells. Both succeeded, and the Koprowski strains were tested extensively in the former Belgian Congo, his native Poland, and elsewhere (2). Nevertheless, because the Sabin strains were less neurovirulent in monkeys and were given successfully to millions of children in the former Soviet Union, they achieved licensure in the United States and adoption by the WHO for use throughout the world. During the battle between the oral polio vaccines, the