Synthesis of vaccinia viral antigens in HeLa cells in the presence of isatin beta thiosemicarbazone

Vaccinia virus antigens, in HeLa cells treated with the antipox virus drug isatin β-thiosemicarbazone (IBT), were analyzed by immunoprecipitation, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The total radioactivity in the immunoprecipitate was decreased to almost 50% in the presence of the drug as compared to its absence. An inhibition also occurred with an IBT-dependent mutant (IBT(D)) when growing in the absence of IBT. However, similar levels of radioactivity were observed in the immunoprecipitates from an IBT-resistant mutant (IBT(D)) grown in either the absence or presence of the drug. When the antigens within the immunoprecipitates were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, it was shown that the inhibition observed in the wild type infected cells in the presence of IBT and in the IBT(D)-infected cells in the absence of the drug, was quantitative, affecting the amounts of the different polypeptides more or less equally.