Alfred Day Hershey (December 4, 1908 - May 22 1997) was a Nobel Prize-winning bacteriologist.

He received his B. S. in chemistry at Michigan State University in 1930 and his Ph. D. in bacteriology in 1934, taking a position shortly thereafter at the Department of Bacteriology at Washington University in St. Louis.

He began performing experiments with bacteriophages with Italian-American Salvador Edward Luria and German Max Delbruck in 1940, and observed that when two different strains of bacteriophage have infected the same bacteria, the two viruses may exchange genetic information.

He moved to Cold Spring Harbor, New York in 1950 to join the Carnegie Institution of Washington's Department of Genetics, where he performed the famous blender experiment with Martha Chase in 1952. This experiment provided more evidence that DNA, not protein, was the genetic material.

He became director of the Carnegie Institution in 1962 and was awarded the Nobel Prize in Physiology or Medicine in 1969, shared with Luria and Delbruck for their discovery on the replication of viruses and their genetic structure.

Further reading

A.D. Hershey and M. Chase, 1952. Independent functions of viral protein and nucleic acid in growth of bacteriophage. Journal of General Physiology 36: 39-56.