Molecular characterization of infectious bronchitis virus isolates foreignto the United States and comparison with United States isolates

Eleven infectious bronchitis virus (IBV) isolates foreign to the United Sta tes were analyzed by using reverse transcriptase (RT)-polymerase chain reac tion (PCR)/restriction fragment length polymorphism (RFLP) and S1 glycoprot ein gene sequencing. Two of the isolates generated RFLP patterns that resem bled the Mass 41 strain. Seven novel RFLP patterns were detected among the other nine foreign IBV isolates. Five of the foreign isolates were further analyzed by S1 glycoprotein gene sequencing in our laboratory Phylogenetic analysis of S1 glycoprotein-deduced amino acid sequences for 4/91 pathogeni c. 4/91 attenuated, and Variant 1 were greater than 90% similar to viruses belonging to the 793/B serogroup and, therefore, are possibly serologically related. Variant 2 was only 81.0% similar to viruses belonging to the Euro pean serogroup B, and, therefore, predicting its serotype is difficult. Iso lates 98-07484 and 97-8123 were genotypically unique and therefore might be serologically unique. With the RFLP patterns and the deduced S1 amino acid sequence data as a reference, none of the IBV isolates foreign to the Unit ed States have been detected in the United States.