Ribonucleic acid-dependent ribonucleic acid polymerase in the immune response.

Ribonucleic acid (RNA)-dependent RNA polymerase activity was demonstrated in the microsomal and ribosomal fraction from the spleen cells of immunized mice. The enzyme activity was solubilized by Triton X-100 from the fraction and partially purified by Biogel A 1.5 m column chromatography. The RNA-dependent RNA polymerase activity was eluted in a single peak from the column. High activity was demonstrated with an RNA polymerase activity was eluted in a single peak from the column. High activity was demonstrated with an RAN preparation (iotaRNA) as template made from the spleens of immunized mice but very low activity was found with an RNA preparation made from the spleens of normal mice. Incorporation of 3H-UTP markedly decreased in the presence of RNase but not in the presence of DNase. DNA preparations made from the spleens of immunized mice were inactive as template for this enzyme. The iotaRNA preparation was fractionated by sucrose density gradient centrifugation. A fraction corresponding to 12-13 S was most active as a template. It was followed by a fraction corresponding to 6-7 S. Sucrose gradient analysis of the 3H-UTP-labeled product was attempted. Some properties of this enzyme are described.