Use of monoclonal antibodies in the characterisation of avian paramyxovirus type 1 (Newcastle disease virus) isolates submitted to an international reference laboratory.

A total of 106 Newcastle disease viruses submitted to the International Reference Laboratory at the Central Veterinary Laboratory, Weybridge from field investigations in 15 different countries was characterised using pathogenicity index tests in chickens and mouse monoclonal antibodies raised against NDV-Ulster 2C (Russell and Alexander, Archives of Virology, 75: 243, 1983) and pigeon isolate 617/83. These isolates could be placed into six distinct groups on the basis of their reaction with the monoclonal antibodies although four isolates gave ambiguous results and remained untyped. Forty isolates, obtained from chickens (21), pigeons (16), a duck (1), a sparrow (1) and a kestrel (1), were indistinguishable from isolates which were responsible for the recent panzootic in pigeons. Twenty-one isolates from domestic poultry, one isolate from a pheasant and one from a chicken in quarantine were identified as vaccinal virus of Bi or La Sota type. Thirty-five isolates placed in the same monoclonal antibody group were velogenic viruses. These had been obtained from domestic poultry in Italy, Austria, Mauritius and Saudi Arabia during 1983-1985, commercial pigeons in Hong Kong in 1986 and exotic birds in Italy, Great Britain and the Federal Republic of Germany during 1981-1985. This group was distinguishable from velogenic viruses responsible for disease outbreaks in poultry during the 1970s. Two lentogenic isolates from commercial ducks in England showed different monoclonal antibody binding patterns both of which have been associated with feral ducks. An isolate from chickens in Italy was also placed in one of these groups. A single isolate from a loon (Gavia sp) in the USA showed a monoclonal antibody binding pattern which had not been seen previously. In addition, 11 vaccinal or laboratory viruses were received for confirmatory characterisation which was greatly aided by the use of the monoclonal antibodies.