Sequencing of coronavirus IBV genomic RNA: three open reading frames in the 5' 'unique' region of mRNA D.

The nucleotide sequence of a genomic cDNA clone corresponding to the 5' terminal domain of mRNA D of the Beaudette strain of infectious bronchitis virus (IBV) has been determined. This region contains three open reading frames which predict polypeptides of molecular weights 6700 (6.7K), 7.4K and 12.4K. The predicted 12.4K polypeptide has a codon usage very similar to that predicted for the products of the IBV nucleocapsid, membrane and spike genes. The sequence also predicts a hydrophobic, potentially membrane-anchoring, region in the N terminal half of the 12.4K polypeptide, and a hydrophilic C terminus.