BIOCHEMICAL CLASSIFICATION OF HERPES-SIMPLEX VIRUS TYPE-1 AND TYPE-2, AND OF INTERMEDIATE STRAINS ON BASIS OF DIFFERENT SUSCEPTIBILITIES OF THYMIDINE KINASE TO THYMIDINE ANALOGS

Abstract

Herpes simplex virus (HSV) type 1 can be differentiated from HSV type 2 on the basis of the sensitivity to 2''-deoxythymidine-5''-monophosphate of thymidine kinase [EC 2.7.1.21] induced in primary rabbit kidney cells. Whereas thymidine kinase induced by 5 strains of HSV type 1 (TK 1) is stimulated by suitable concentrations of 2''-deoxythymidine-5''-monophosphate, thymidine kinase induced by 8 strains of HSV type 2 (TK 2) is inhibited. TK 2 is strongly inhibited by 2''-deoxythymidine-5''-triphosphate and by 2-bromo-2''-deoxyuridine-5''-triphosphate. The investigation of TK induced by 6 freshly isolated strains of HSV corss-reacting in neurtralization tests revealed 2 strains which induced TK 1 and 2 strains which induced TK 2. Two other strains induced thymidine kinase, the activity of which under the influence of these thymidine analogues was between that of TK 1 and TK 2. The properties of thymidine kinase remained constant after cloning the virus and thus is a genetically fixed trait due to recombination which could occur in vivo.