The natural outbreaks of the enzootic disease in the duck have been recorded in Zhejiang province,and one virus, which caused duck egg laying drop was isolated from duck.The virus was identified as avian paramyxovirus-1 and designated as strain YH_(99)V.Using the viral genome RNA as template,cDNA fragments of HN gene of strain YH_(99)V was amplified by one-step RT-PCR which was cloned into pMDI8-T vector and sequenced.The complete sequence of HN gene was obtained finally and the nucleotide sequence of HN ge...