That turned out to be a very good move:
"In 1956 I reviewed for Virology a note by Groupé and Manaker reporting an assay of RSV in cell culture by production of transformed foci (21). A significant difference from my efforts to assay RSV in culture was their addition of tryptose phosphate broth to the medium. I enlisted Howard Temin, a first-year graduate student in embryology, to help in adaptation of the RSV focus assay to Dulbecco's monolayer assay of cytocidal viruses "