Cellular and Epstein-Barr virus specific DNA polymerases in virus-producing Burkitt's lymphoma cell lines

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Abstract
We have determined the levels of cellular DNA polyinerases and Epstein-Barr virus specific DNA polymerase in three Burkitt's lymphorna cell lines producing varying amounts of EBV, one of which was induced by 12-0-tetradecanoylphorbol-l3-acetate (TPA). There was a proportional increase in the level of EBV-DNA polymerase with an increase in the percent of virus-producing cells. However, there was a reciprocal relationship between the levels of EBV-DNA polymerase and DNA polymerase α i.e., in cell line containing the highest level of EBV-DNA polymerase, activity of DNA polymerase α, but not of DNA polymerase , was reduced to an insignificantly low level. TPA does not have any direct effect on activities of either EBV-DNA polymerase or DNA polynierase a. EBV-DNA polymerases isolated from cells grown with or without TPA are Indistinguishable in their properties such as elution position on phosphocellulose column, molecular weight, mono and divalent cation require ments, pH optimum, and other requirements for optimum activity. Addition of crude extracts of cells grown In presence of TPA to the purified DNA poly rnerase a did not inhibit its activity indicating that the observed loss was not due to any specific inhibitor present in TPA treated cells. Raji, a non producer cell line, did not contain EBV-DNA polymerase. There was no induc tion of EBV-DNA polymerase when Raji cells were grown In presence of TPA. The phenomenon of reduction in the levels of DNA polymerase a in cells in duced to produce EBV may represent a mechanism by which the host DNA replica tion is shut off following virus infection.