How did Renato Dulbecco adapt plaque techniques to study animal viruses?

Renato Dulbecco adapted plaque techniques to study animal viruses by applying a method previously used for bacterial viruses. Scientists had been measuring the number of bacterial viruses by observing their ability to create clearings, or "plaques," in a lawn of bacteria overlaid with agar. In 1952, Dulbecco applied this technique to animal viruses, measuring their numbers by their capacity to produce plaques in layers of animal cells, also overlaid with agar. This innovation allowed for the quantitative study of animal viruses, contributing significantly to virology and his shared Nobel Prize in Physiology or Medicine in 1975.12