Bryan Williams is internationally recognized for his work on innate immunity and mechanisms of interferon action. His discoveries include 2’-5’ oligoadenylate activated endoribonuclease, cloning and characterization of protein kinase R, first description of induced gene expression profiles in mammalian cells, and most recently the critical role played by promyleocytic zinc finger protein in innate immunity. He has also determined the mechanisms by which cells detect siRNAs and activate an innate immune response. This world-leading work is not only important for understanding defensive responses to viral infections but also has important implications for the use of siRNA in research and therapy.