Confirmation of the presence of avian infectious bronchitis virus (IBV) using cloned DNA complementary to the 3' terminus of the IBV genome.

A hybridisation test has been developed to aid the identification of virus isolates as avian infectious bronchitis virus (IBV) when serum neutralisation tests have proved inadequate. In this test nucleic acid prepared from four recent virus isolates suspected of being IBV hybridised with a 32P-radiolabelled cloned cDNA (complementary DNA) probe complementary to RNA from IBV strain Beaudette. Since these strains represent one or more new serotypes they had not been identified by neutralisation tests using antisera to known IBV serotypes. Polyacrylamide gel electro-phoresis of the isolates radiolabelled in de-embryonated eggs showed that the viruses had proteins characteristic of IBV. Nine other IBV strains, representing five serotypes, also hybridised with the probe.