Altered base ratios in RNA synthesized during enterovirus infection of human cells

EFFECT OF ACTINOMYCIN D ON RNA SYNTHESIS AND ANTIBODY FORMATION IN THE ANAMNESTIC RESPONSE IN VITRO

Antibody synthesis in anamnestic lymphoid cells, measured by incorporation of leucine-C¹⁴ into specific antibody, was inhibited at moderate concentrations of actinomycin D. This was accompanied by marked inhibition of synthesis of RNA as measured by incorporation of H³-cytidine monophosphate. However, at low concentrations of actinomycin D, antibody synthesis was unaffected or even increased while RNA synthesis continued to be inhibited. The results obtained suggest that messenger RNA for antibody synthesis, either because it is relatively stable or present in excess, does not become a limiting factor until its synthesis is maximally inhibited. Puromycin, an inhibitor of amino acid coupling, abolished antibody synthesis in low concentration. 6-Mercaptopurine had no effect on the synthesis of antibody or RNA even at high concentration. The data obtained support the view that antibody synthesis follows pathways similar to those utilized for the formation of other types of proteins.

Double-Stranded Ribonucleic Acid Formation in vitro by MS 2 Phage-Induced RNA Synthetase

Part of the RNA synthesized from nucleoside triphosphate precursors by partially purified RNA synthetase, an enzyme induced in Escherichia coli by the RNA-containing phage MS 2, is resistant to hydrolysis by ribonuclease. Upon heating in 0.15M sodium chloride, 0.015M sodium citrate followed by fast cooling the material becomes ribonuclease-sensitive with a sharp transition at 102 degrees to 104 degrees C. The suggestion that the ribonuclease-resistant product is double-stranded RNA is reinforced by restoration of the ribonuclease resistance of the heat-denatured material by reannealing at temperatures just below the transition point and by its buoyant density in cesium sulfate. It is suggested that double-stranded RNA is the replicative form of MS 2 phage RNA.