Biochemical Transformation of Mouse Cells by Varicella-Zoster Virus

Abstract

Mouse L cells lacking the enzyme thymidine kinase (Ltk-) were infected with varicella-zoster virus (VZV). Even though virus did not replicate in Ltk- cells, the presence of virus antigen could be observed by use of an anti-complement immunofluorescent technique at 4 h post-infection and the VZV-specific thymidine kinase could be detected in VZV-infected Ltk- cells. Ltk- cells were converted to a tk+ phenotype (Ltk+) by infection with cell-associated VZV. Clones possessing the ability to grow in selective medium were isolated and cultured successfully for > 20 passages. One clone grew very slowly, but other clones showed almost the same growth rate as that of the parental Ltk- cells. Chromosome analyses of Ltk- cells and transformed cells revealed that the isolated clones were of mouse origin. VZV-specific antigen could be detected in the nuclei of Ltk+ cell clones by an immunofluorescent test; tk activity was greatly enhanced in extracts prepared from transformed cells and its activity was neutralized by hyperimmune serum against VZV.