Drosophila X virus RNA polymerase: tentative model for in vitro replication of the double-stranded virion RNA.

An RNA polymerase activity was found to be associated with the infectious drosophila X virus particles extracted from infected flies. The rate of synthesis was at first linear as a function of time, and then a plateau was reached. During the linear phase of the synthesis, the template and product were associated as replicative intermediates which were larger than the double-stranded RNA of the drosophila X virus genome, but the final product of the reaction was indistinguishable from the RNA genome with respect to its density, sedimentation coefficient, electrophoretic mobility, and RNase resistance. The results indicated that both strands of the genomic RNA were copied. The implications of these findings with regard to other virion polymerases are discussed.