INHIBITION OF DNA-SYNTHESIS IN BHK CELLS INFECTED WITH WESTERN EQUINE ENCEPHALITIS-VIRUS .1. INDUCTION OF AN INHIBITORY FACTOR OF CELLULAR DNA-POLYMERASE ACTIVITY

Infection of baby hamster kidney cells with western equine encephalitis virus results in rapid inhibition of cellular DNA synthesis. As reported previously (Simizu et al., 1976), this inhibition is not due to degradation of DNA nor suppression of precursor uptake. As the next approach, it was examined whether cellular DNA polymerase activity is inhibited or not. DNA polymerase activity in infected cell extracts was found to be decreased parallel to the decline of DNA synthesis with time after infection. This inhibition was ascribed to an inhibitory factor(s), much of which was found in 105,000 g pellet of the extract. This factor was thermolabile and was solubilized with high concentration of salt, but not with Triton X-100 or urea. Molecular weight of the solubilized factor was determined to be 83,000 by sedimentation analysis. No apparent specificity of inhibition was observed with several DNA polymerase species tested. Furthermore, activity of the inhibitory factor was suppressed by inorganic phosphate. These results may predict that the factor does not affect the DNA polymerase molecule itself, but is a hydrolytic enzyme of precursor deoxynucleotides. The possibility that this inhibitory factor is a virus-coded protein is discussed. © 1979.