Avian infectious bronchitis virus genomic RNA contains sequence homologies at the intergenic boundaries

cDNAs derived from the 3'-terminus of IBV Beaudette genomic RNA by oligo(dT)-primed reverse transcription were cloned in PAT153/HB101. 25 clones were characterised and two of these were found to cover 3.3 kb extending from the poly(A) tail. The relationships of the two smallest IBV mRNAs, A and B, to the cloned sequences were established by restriction fragment hybridisation to Northern blots. The 5'-termini of mRNAs A and B were located on the clones by S1 mapping. DNA sequencing of cloned sequences corresponding to the intergenic boundaries of mRNAs A and B was carried out. Homologies between the sequences at these boundaries were observed.