The influence of iododeoxyuridine pretreatment of various cell cultures on adenovirus multiplication.

Treatment of cell cultures with iododeoxyuridine (IUdR) before virus inoculation may enhance the subsequent virus multiplication. This effect was studied in seven kinds of cell cultures with seven human adenoviruses from six subgenera. IUdR (50 micrograms/ml) was added 24 h after the seeding of cells, left for 2 days, and removed before virus inoculation. IUdR had no effect on cell proliferation. Viral cytopathic effect was enhanced in many instances by IUdR pretreatment. However, virus multiplication was enhanced weakly in only four cases [adenovirus 7 in Vero, African green monkey kidney, cynomolgus monkey kidney; adenovirus 4 (Ad4) in HeLa cells], and strongly only for Ad4 in Vero cells, which are semipermissive for Ad4. IUdR pretreatment of Vero cells shortened the replication cycle for Ad4 and increased sensitivity for minimal virus concentrations about 1000-fold. From immunofluorescence experiments it appears that more than one infectious particle is required to infect an untreated Vero cell.