Novel variation in the N protein of avian infectious bronchitis virus.

Abstract

The nucleocapsid protein of coronaviruses has been considered highly conserved, showing greater than 94% conservation within strains of a given species. We determined the nucleotide sequence of the N gene and the 3' untranslated region (UTR) of eight naturally occurring strains of IBV which differed in pathogenicity and tissue tropism. In pairwise comparisons, the deduced amino acid sequences of N of five strains Vic S, N1/62, N9/74, N2/75, and V5/90 (group I) shared 92.3-98.8% identity. The three strains N1/88, Q3/88, and V18/91 (group II) shared 85.8-89.2% identity with each other, but only 60.0-63.3% identity with viruses of group I. Amino acid substitutions, deletions, and insertions occ..