Nucleotide sequence of the human coronavirus 229E RNA polymerase locus

The nucleotide sequence of the human coronavirus 229E (HCV 229E) RNA polymerase gene and the 5' region of the genome has been determined. The polymerase gene is comprised of two large open reading frames, ORF1a and ORF1b, that contain 4086 and 2687 codons, respectively. ORF1b overlaps ORF1a by 43 bases in the (-1) reading frame. The in vitro translation of SP6 transcripts which include HCV 229E sequences encompassing the ORF1a/ORF1b junction show that expression of ORF1b can be mediated by ribosomal frame-shifting. The predicted translation products of ORF1a (454,200 molecular weight) and ORF1a/1b (754,200 molecular weight) have been compared to the predicted RNA polymerase gene products of infectious bronchitis virus (IBV) and murine hepatitis virus (MHV) and conserved structural features and putative functional domains have been identified. This analysis completes the nucleotide sequence of the HCV 229E genome.