Analysis of deoxycytidine (dC) deaminase activity in herpes simplex virus-infected or HSV TK-transformed cells: association with mycoplasma contamination but not with virus infection.

Deoxycytidine (dC) deaminase activity has been previously reported to be induced in herpes simplex virus (HSV)-infected cells (Chan, 1977). In contrast, we report here that HSV infection of either hamster cells naturally deficient in this enzyme activity or mouse cells containing a low level of activity never resulted in appearance of stimulation of dC deaminase, whereas thymidine kinase (TK) was always induced. Surprisingly, dC deaminase activity, which differed by electrophoretic mobility from the mouse or human cell enzyme, was discovered in some cells selected for the presence of HSV TK after infection with u.v.-irradiated HSV. Evidence is presented which suggests that the appearance of this new enzyme was not due to the presence of virus genes but rather to mycoplasma contamination.