CORONAVIRUS TRANSCRIPTION MEDIATED BY SEQUENCES FLANKING THE TRANSCRIPTION CONSENSUS SEQUENCE

In our studies of murine coronavirus transcription, we continue to use defective interfering (DI) RNAs of mouse hepatitis virus (MHV) in whi ch we insert a transcription consensus sequence in order to mimic subg enomic RNA synthesis from the nondefective genome. Using our subgenomi c DI system, we have studied the effects of sequences flanking the MHV transcription consensus sequence on subgenomic RNA transcription. We obtained the following results. (i) Insertion of a 12-nucleotide-long sequence including the UCUAAAC transcription consensus sequence at dif ferent locations of the DI RNA resulted in different efficiencies of s ubgenomic DI RNA synthesis. (ii) Differences in the amount of subgenom ic DI RNA were defined by the sequences that flanked the 12-nucleotide -long sequence and were not affected by the location of the 12-nucleot ide-long sequence on the DI RNA. (iii) Naturally occurring flanking se quences of intergenic sequences at gene 6-7, but not at genes 1-2 and 2-3, contained a transcription suppressive element(s). (iv) Each of th ree naturally occurring flanking sequences of an MHV genomic cryptic t ranscription consensus sequence from MHV gene 1 also contained a trans cription suppressive element(s). These data showed that sequences flan king the transcription consensus sequence affected MHV transcription. (C) 1996 Academic Press, Inc.