Sensitivity of Types 1 and 2 Herpes Simplex Virus to 5-Iodo-2′-Deoxyuridine and 9-β- d -Arabinofuranosyladenine

The sensitivities of 21 strains of herpes simplex virus (HSV), 13 type 1 strains and 8 type 2 strains, to 5-iodo-2'-deoxyuridine (IUdR) and 9-beta-d-arabinofuranosyladenine (ara-A) were evaluated by the plaque-suppression test in chick embryo fibroblast (CEF), WI-38, and HeLa cell cultures. In CEF, type 1 strains were considerably more sensitive to the inhibitors than were the type 2 strains. In WI-38, the type 1 strains were more sensitive than the type 2 strains to IUdR; however, the two serotypes were equally sensitive to ara-A. In HeLa cells, the differences in sensitivity to IUdR between the two serotypes were less. Eight HeLa-adapted strains (four type 1 and four type 2) evaluated in HeLa cell cultures were equally sensitive to IUdR; the type 2 strains were slightly more sensitive than type 1 strains to ara-A. These results demonstrate the wide variation in sensitivity of HSV types 1 and 2 to antiviral agents which results from differences in the cell culture system and passage history of the strains.