MOLECULAR-CLONING AND SEQUENCE COMPARISON OF THE S1 GLYCOPROTEIN OF THE GRAY AND JMK STRAINS OF AVIAN INFECTIOUS-BRONCHITIS VIRUS

The nucleotide sequences of S1 glycoprotein genes of the Gray and JMK strains of avian infectious bronchitis virus (IBV) were determined and compared with published sequences for IBV. The IBV Gray and JMK strai ns had 99% nucleotide sequence similarity. The overall nucleotide sequ ence similarity of the Gray and JMK strains compared with other IBV st rains was between 82.0% and 87.4%, The similarity of the predicted ami no acid sequence for the S1 glycoproteins of the Gray and JMK strains was 98.8%, Six of the 10 differences in the amino acid sequence were f ound between residues 99 and 127, suggesting a possible role for that region in the tissue trophisms of the viruses, The S1 glycoprotein of the Gray and JMK strains had 79.5%-84.6% amino acid similarity with th e published sequence of other IBV strains, Serine instead of phenylala nine was observed in the protease cleavage site between the S1 and S2 glycoprotein subunits for the Gray and JMK strains, which was similar to the published sequence for the Ark99 and SE17 strains. The signific ance of that amino acid change is not known. Based on the nucleotide s equence of the Gray and JMK strains, the BsmAI restriction enzyme was selected by computer analysis and was used in restriction fragment len gth polymorphism analysis to differentiate the two strains.