Rolf M. Zinkernagel
Together with the Australian Peter C. Doherty he received the 1996 Nobel Prize in Physiology or Medicine for the discovery of how the immune system recognizes virus-infected cells. With this he became the 24th Swiss Nobel laureate.
Viruses infect host cells and reproduce inside them. Killer T-cells destroy those infected cells so that the viruses can't reproduce. Zinkernagel and Doherty discovered that, in order for killer T cells to recognize infected cells, they had to recognize two molecules on the surface of the cell -- not only the virus antigen, but also a molecule of the major histocompatibility complex (MHC). This recognition was done by a T-cell receptor on the surface of the T cell. The MHC was previously identified as being responsible for the rejection of incompatible tissues during transplantation. Zinkernagel and Dougherty discovered that the MHC was responsible for the body fighting meningitis viruses too. 
He received his MD from the University of Basel in 1970 and his PhD from the Australian National University in 1975. In addition to the Nobel Prize, he also won The Albert Lasker Medical Research Award in 1995.