Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 8, 1997
Publication Date: N/A
Interpretive Summary: Any bird infected with Newcastle disease virus (NDV) is a hazard to susceptible poultry. Urban live bird markets are a source of several bird species including some coming from poultry farms. NDV is frequently isolated in surveillance sampling in these markets, but none of those isolates have been fully characterized. Six NDV isolates from markets in the Northeastern U.S. were characterized by procedures that included determining the pathogenicity for chickens as well as other biological and molecular properties. None were pathogenic for chickens, but two of the isolates were found to be quite unusual and both were different than any isolate previously identified in the U.S. A chicken isolate had gene sequences that differed to the extent that the isolate may be the sole representative of a third NDV phylogenetic group. A pheasant isolate is similar to two NDV viruses of low virulence found in Northern Ireland and Australia but not reported previously in the U.S. The properties that make the unusual viruses unique would be missed by standard diagnostic methods which typically identify a virus as NDV and determine its pathogenicity for chickens. The frequency of these unusual isolates of low virulence will remain unknown until more viruses receive more extensive characterization. Traffic between these markets and poultry farms poses a hazard for spread of these unusual viruses.
Technical Abstract: Newcastle disease virus (NDV) is frequently recovered from surveillance samples collected by USDA, APHIS personnel in live bird markets. Six NDV isolates, five from chickens and one from a pheasant, were characterized for comparison with NDV isolates from poultry and other birds. All viruses were of low virulence for chickens. Four of the six viruses were similar to the lentogens B1 and La Sota, but two, isolates from a chicken and a pheasant, were different. The aberrant chicken isolate had a monoclonal antibody (mAb) binding profile like an unusual Canadian pigeon isolate. Sequence analysis of the matrix (M) gene of this isolate demonstrated that it differed from all isolates in the comparison and may represent a third phylogenetic NDV group. The pheasant isolate had a mAb reactivity like other U.S. NDV lentogens, but had an M gene sequence and hemagglutinin thermostability similar to strains Ulster and QV4, viruses originally isolated in Northern Ireland and Australia, respectively. The pheasant virus is the first U.S. lentogen known to be closely related phylogenetically to Ulster and QV4. The unusual chicken and pheasant isolates were readily shed from the intestinal tract during chicken passage, whereas the other isolates were shed from the respiratory tract with little or no intestinal shedding. The frequency of these viruses similar to those previously thought to be exotic to the U.S. is unknown.