Biochemical and serological properties of the thymidine-phosphorylating enzymes induced by herpes simplex virus mutants temperature-dependent for enzyme formation.

Evidence is presented in support of the hypothesis that: (i) an enzyme induced by wild-type herpes simplex virus type 1 (HSV-1) is a deoxypyrimidine kinase with a single active site for the phosphorylation of both thymidine (TdR) and deoxycytidine (CdR); (ii) enzymes induced by HSV-1 mutants that are temperature dependent for enzyme induction are altered with respect to nucleoside acceptor specificity and antigenicity; and (iii) altered polypeptides are synthesized in mutant virus-infected cells at both the permissive (31°) and restrictive (37.5°) temperatures. HSV-1 mutants B2010 and B2015 induce less TdR-phosphorylating activities at 31° than wild-type HSV-1 and very low but detectable enzyme activities at 37.5°. The TdR-phosphorylating activities induced by the mutant viruses at 31° have the same electrophoretic mobilities as that of the wild-type HSV-1-induced enzyme but, unlike the wild-type enzyme, the mutant enzymes lack CdR-phosphorylating activity. Immunoglobulin G (IgG) prepared from rabbits immunized with cytosol extracts from rabbit kidney cells infected with wild-type HSV-1 inhibit the TdR-phosphorylating activities induced by wild-type and mutant viruses, as well as the CdR-phosphorylating activity induced by wild-type HSV-1. Extracts purified from cells infected at 31° with wild-type and mutant HSV-1 blocked the neutralizing activity of anti-HSV-1 IgG for the CdR- as well as the TdR-phosphorylating activities of wild-type HSV-1 enzyme, despite the lack of CdR-phosphorylating activity of the mutant enzyme. However, the mutant virus-infected cell extracts were less effective than wild-type extracts in serum blocking activity. Extracts from cells infected with mutant B2015 at 37.5° did not exhibit serum blocking power.