Human cytomegalovirus-induced inhibition of exogenous thymidine uptake into cell DNA in HEL cells stimulated to proliferate with serum.

In contrast with the previous findings by us and others, human cytomegalovirus (HCMV) infection caused inhibition of exogenous 3H-dThd uptake into cell DNA in human embryonic lung (HEL) cells which were stimulated to proliferate with serum at the time of infection. The response of HEL cells to HCMV infection varied depending on the HEL cell population, and the inhibition of 3H-dThd incorporation was observed in a particular HEL cell population prepared in our laboratory. That the inhibition was caused by HCMV virion was shown by: (i) antiserum against HCMV prevented the virus inoculum from inhibiting 3H-dThd uptake, and (ii) removal of virions from an infecting virus stock by centrifugation resulted in no inhibition. The virus-induced inhibition was enhanced by uv-irradiation of infecting virus, suggesting that the expression of viral gene functions was not necessarily required for the inhibition. comparison between autoradiography of 3H-dThd-labeled infected cells and the total amounts of 3H incorporated into DNA indicated that HCMV reduced the overall rate of 3H incorporation into DNA in infected cells and the number of cells entering the S phase of the cell cycle.