Nucleotide sequence of infectious bursal disease virus genome segment A delineates two major open reading frames

The genome of infectious bursal disease virus (IBDV) consists of two segments of double stranded RNA. The authors have determined the sequence of the larger segment A, encoding 3 structural polypeptides, of IBDV strain Cu-1. Sequencing of overlapping cDNA clones revealed the presence of two major open reading frames (ORFs). In addition to a large ORF (nucleotides 96 to 3132), they found a small ORF (nucleotides 62 to 497), overlapping the large ORF. Another start codon, at position 30, lies between a perfect Kozak consensus sequence; this ORF is terminated at position 60, prior to the start codons of the major ORFs.