Evidence for an RNA Replicative Intermediate in Cells Infected with Newcastle Disease Virus

Cells infected with Newcastle disease virus contained significant amounts of base-paired RNA. Base pairing in this RNA was suggested by its resistance to ribonuclease and by the sharp thermal transition from ribonuclease resistance to sensitivity at 83° in 0.01 m-NaCl. The base-paired RNA sediments heterogeneously with a peak at 35 s.

Preferential labelling of the base-paired RNA after short periods of incubation with [3H]uridine suggests that it may serve as an intermediate in the synthesis of single-stranded virus-specific RNA. The kinetics of [3H]uridine incorporation into the various species of virus-specific RNA are discussed.