ANTIGENIC DIVERSITY AND SIMILARITIES DETECTED IN AVIAN PARAMYXOVIRUS TYPE-1 (NEWCASTLE-DISEASE VIRUS) ISOLATES USING MONOCLONAL-ANTIBODIES

Newcastle disease (ND) virus (APMV-1) isolates submitted to the Intern ational Reference Laboratory for ND were characterised antigenically b y their ability to cause binding of mouse monoclonal antibodies (mAbs) to cell cultures infected with the isolate. Since the availability of the mAbs 1526 viruses have been examined using a panel of nine mAbs a nd 818 with an extended panel of 26 mAbs. Using the nine mAb panel a t otal of 14 different patterns was seen and viruses grouped by the same pattern showed relationships with each other which were either biolog ical, temporal or geographical or more than one of these. There was a marked tendency of viruses placed in the same group to show similar vi rulence for chickens. Extension of the panel to 26 mAbs produced 39 di stinct patterns, although some of these were seen with only a single v irus. Again, viruses inducing similar binding patterns shared similar properties and some binding patterns were specific for viruses causing discrete epizootics. Cluster analysis of the mAb binding patterns did not produce concise, discrete groupings, but did emphasise some relat ionships between virus properties and antigenicity. Examples of the us efulness of this approach were the ability to link two important outbr eaks to the contamination of stored food by infected feral pigeons, an d the demonstration of two separate viruses responsible for outbreaks in countries of the European Union during 1991 to 1994 thus preventing erroneous epizootiological tracing.