ISOLATION AND PRELIMINARY IDENTIFICATION OF A VIRULENT NEWCASTLE DISEASE VIRUS LSOLATE OF DUCK ORIGIN

A virus was isolated from the dead laying ducks,which mainly manifested by diarrhea,nervous signs,focal haemorrhage and necrosis of the intestinal mucosa,and congestion and haemorrhage of the ovarian follicles.The virus,designated as JSD0812,was preliminarily identified to be a Newcastle disease virus(NDV) by haemagglutination(HA),haemagglutination-inhibition(HI),serum neutralization(SN) tests and sequencing of its partial fusion(F) gene.The mean death time(MDT) in 10-day-old embryonated SPF chicken eggs,intracerebral pathogenicity index(ICPI) in 1-day-old SPF chickens and intravenous pathogenicity index(IVPI) in 6-week-old SPF chickens were 54.6 h,1.75 and 2.68,respectively.It had the sequence 112R-R-Q-K-R-F117 at the cleavage site of F protein,which was typical for virulent NDV strains.The results demonstrated the isolate was a virulent NDV strain.In the pathogenicity experiment the isolate was highly pathogenic to chicken,duck and goose.