Structural and functional characterization of Newcastle disease virus polycistronic RNA species

Upon infection, the Newcastle disease virus (NDV) genome is transcribed to produce 18S, 22S, and 35S RNAs (M. Bratt , and W. Robinson, J. Mol. Biol. 23:1-21, 1967). The 22S RNA has been shown to contain 18S sequences and is thought to represent polycistronic transcripts generated by transcriptional readthrough of adjacent genes ( Varich et al., Acta Virol. 23:341-343, 1979). With improved extraction procedures, the 22S RNA was found to represent up to 25% of the total transcription in NDV-infected cells. This RNA was resolved into at least five discrete species on formaldehyde-agarose gels. All but one of these molecules contain 3' polyadenylate sequences but not internal polyadenylate sequences. These transcripts are found on polyribosomes of infected cells, suggesting that they are functional mRNAs.