Fig. 3.

Alignment of the predicted amino acid sequences of the subgroup 2 3b genes with those of vaccine strains VicS and Armidale. a) Alignment of the predicted amino acid sequences of gene 3b of Australian subgroup 2 strains N1/88, Q3/88 V18/91 and V6/92 with Australian vaccine IBV strains VicS and Armidale. Identical amino acids and bases are indicated by an asterisk (*). Conserved amino acid changes are represented by “:”, while semi-conserved amino acid changes are identified by “.”. b) Nucleotide sequence alignment of the first three codons of gene 3b. The initiation codon is boxed to show the altered initiation codon in the subgroup 2 strains