Antigenic and genetic characterisation of Newcastle disease viruses isolated from outbreaks in domestic fowl and turkeys in Great Britain during 1997

Antigenic and genetic analyses of viruses from the 11 outbreaks of Newcastl e disease in Great Britain, 12 of the outbreaks in Northern Ireland and the single outbreak in the Republic of Ireland which occurred in 1997, indicat ed that they were all essentially similar. In addition, the viruses from th e British Isles were very similar to viruses isolated from three outbreaks in pheasants in Denmark between August and November 1996, from a goosander in Finland in September 1996, from an outbreak in chickens in Norway in Feb ruary 1997, and from an outbreak in chickens in Sweden in November 1997 Vir uses from outbreaks in other countries during 1995 to 1997 could be disting uished antigenically and/or genetically from the 1996 to 1997 Scandinavian/ British Isles isolates, as could viruses responsible for two separate outbr eaks in caged birds in quarantine premises in Great Britain in March 1997. Minor nucleotide differences in the 413-base region of the fusion gene and the 187-base region of the haemagglutinin-neuraminidase gene sequenced in t his study allowed the 1996 to 1997 Scandinavian/British Isles isolates to b e divided into groups. These groups broadly corresponded to the clusters of disease outbreaks, but suggested that the discrete outbreak in Scotland wa s probably the result of virus spread from Northern Ireland. Overall, the a ntigenic and genetic analyses of these viruses were consistent with the the ory that the virus was introduced into the British Isles by migratory birds moving from north east Europe. However, it was not possible to rule out ot her sources, such as the movement of pheasants from Denmark.