Isolation,identification and biological characteristic of high virulent chicken NDV

In recent years,there is occurrence ND continuously in the ND La Sota vaccine immunity chicken,(containing high antibody chicken).Some scholars reported its reason relation with not only immunity method,variation of vaccine,etc,but also poison and different genotype.One virus isolate was obtained from the diseased chicken flocks in Heilongjiang province using SPF chicken embryos.By morphologic examination, structure characteristics,biological property,serological tests and pathology characteristic study,this virus was identified as the ND highly virulent strain. New castle disease virus (NDV),whose pathology characteristics were appeared different from those of the standard virulence NDV.LaSota vaccine could not give good protection against the infection of this virus isolate.