COMPARISON OF NEWCASTLE-DISEASE VIRUSES ISOLATED FROM CORMORANTS IN CANADA AND THE USA IN 1975, 1990 AND 1992

Seventeen Newcastle disease virus (NDV) isolates obtained from cormora nts, turkeys, a pelican, and a gull in Canada and the USA collected in 1975, 1990 and 1992 were analyzed for relatedness by monoclonal antib ody profiling, In addition, nucleotide sequence analysis was performed in two areas of the fusion (F) gene for 5 of the isolates, No differe nce in the antigenicity of these 17 viruses, as determined by monoclon al antibody binding patterns, was seen. The amino acid sequences obtai ned via nucleotide sequencing at the cleavage site of the F protein sh owed that all the isolates tested had two pairs of basic amino acids i mmediately upstream of the cleavage site, and a phenylalanine residue at the N-terminus of the F1 protein, which is consistent with velogeni c NDV, The deduced amino acid sequence obtained at the cleavage site o f the F protein from 6 of the isolates was virtually identical regardl ess of the species, year of isolation, or location, However, the 1975 cormorant isolate showed marked differences from the 1990-1992 isolate s in the nucleotide and deduced amino acid sequence of the F gene sign al region, These data indicate that the 1990 and 1992 outbreaks were c aused by the same epizootic virus and further suggest that the populat ion of NDV in these wild birds may be very stable, The belief that the velogenic NDV circulating in cormorants in 1992 was transmitted into the free-ranging turkey flocks located near the cormorants in North Da kota is supported by the present study in which no distinction could b e made between the viruses isolated from turkeys or wild birds.