Sir Frank Macfarlane Burnet (1899-1985), Australian virologist and immunologist. Burnet shared the 1960 Nobel Prize for Medicine with Peter Bryan Medawar. They were awarded the prize for work on antibody reactions to antigens. Burnet's view was that the antigen response is not inborn, but instead developed during foetal life. In the 1930s, his studies of viruses included bacteriophages, which are viruses that attack bacteria. His Clonal Selection Theory of 1951 was controversial and prompted further research. The theory explained how an immune system develops the ability to distinguish between self and non- self.