POLIOVIRUS REPLICASE - SOLUBLE ENZYME ABLE TO INITIATE COPYING OF POLIOVIRUS RNA

The soluble phase of the cytoplasma of poliovirus-infected cells contans an enzymatic activity able to copy RNA without an added primer. This replicase activity has been purified 60-fold; it is absent from uninfected cells. Poly(U) polymerase activity copurifies with replicase activity. Although less pure replicase fractions copy a variety of RNAs, purer fractions respond better to poliovirus RNA than to other viral RNAs. Even the less pure fractions make a specific copy of the added template, as shown by hybridization of the product to its template RNA but not to other RNAs. Among homopolymers only poly(A)oligo(U) was copied by the replicase; other primed homopolymer templates were inactive.