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

Abstract

SUMMARYA 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 32 P-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 electrophoresis 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. (Hopkins, 1974) infectious bronchitis in the United Kingdom is largely controlled by live vaccines of the Massachusetts serotype. However, Cook (1983) has isolated five strains of virus from chickens of five flocks which had been vaccinated against IBV. Although coronavirus-like particles were observed by electron microscopy four strains appeared to be serologically distinct from existing IBV serotypes since they were not neutralised by antisera prepared against strains of five known serotypes (Cook, 1983). It was clearly desirable to confirm that the recent isolates were IBV. To this end a test has been developed for IBV which employs a 32 P-labelled probe prepared from a plasmid which contains cloned DNA complementary (cDNA) to a nucelotide sequence near the 3' end of the genomic RNA of IBV strain Beaudette. Tests of this type have been shown to be highly specific under appropriate conditions (Howley et al., 1979). RNA from crude preparations of putative and known IBV isolates is bound to nitrocellulose filters and then exposed to the probe. Binding of the probe to the filters is readily detected by auto radiography. The test can be used to help identify an isolate as IBV. INTRODUCTION Although infectious bronchitis virus (IBV) exhibits extensive antigenic variation

Comparison of the haemagglutination inhibition test and the serum neutralisation test in tracheal organ cultures for typing infectious bronchitis virus strains

“…In view of the multiplicity of serotypes of IB virus now being described there is a need for a simple and rapid test for typing IB viruses. Possibly a new approach is needed and the use of monoclonal antibodies (Mockett et al, 1984) or techniques involving DNA hybridisation (Brown et al, 1984) or DNA probes might be investigated to advantage. Rowell, J.G., Cook, J.K.A.…”