Thymidine-kinase in cytomegalovirus infected cells.

In human diploid fibroblast LEP cells infected with AD169 strain of human cytomegalovirus (CMV) a sharp increase of cytosol thymidine kinase activity was observed. The properties of the cytosol enzymes from infected and non-infected cells were compared. No significant differences between the enzymes from infected and control cells were observed in substrate specificity, pH dependence, thermostability and relative electrophoretic mobility. Human sera containing high titres of CMV complement-fixing antibodies did not neutralize the enzyme from infected cells. It is concluded from these results that the increase of cytosol thymidinekinase activity in CMV-infected cells was due to an enhancement of cellular thymidine kinase.