Biological Identification Of Duck Paramyxovirus And Sequencing Of F Gene Of Duck Paramyxovirus

Duck Paramyxo virus disease is regarded as one of the most devaetating diseases of poultry in the world, caused by Duck Paramyxo Virus. It is included as an Office International des Epizooties(OIE)list A disease.In the past two decades,an intensive vaccination program against Duck Paramyxo virus disease had been practiced in both large-poultry operations and village poultry farming.This disease breaks out infrequently in some vaccinated flocks.Six Duck Paramyxo Viruses were isolated from shandong province. The Fusion (F) gene of these isolate strains were amplified by reverse transcription-polymerase chain reaction (RT-PCR) technique.The F genes were sequenced after the products of amplification being cloned.So that it can give great help for the study of the prevalence and control. This study included two parts.Part I: Biological Identification of Paramyxovirus Isolated from Ducklings and Duck-embryosA strain virus isolated from duckling and duck-embryos was identified as paramyxovirus by HA , HI and neutralization of virus. The virus was named SDFCH strain. The MDT,ICPI and IVPI for SDFCH strain were 56.6h,1.78 and 2.59.LD50 of duck-embryos is 10-8.5. The results indicated that SDFCH isolate was virulent strain.Ducklings and duck-embryos which were challenged by paramyxovirus SDFCH strain had visible pathological change. The fusion (F) gene of SDFCH strain was amplified by the RT-PCR using three pairs of primers designed according to the published gene sequences . The F gene of SDFCH strain exhibited 96.4%~98.0% nucleotide and 96.4%~98.0% amino acid homology to those of paramyxoviruses isolated from ducks and gooses.But only 84.4% nucleotide and 87.9% amino acid homology to Lasota strain. The results indicated that SDFCH strain was genetically closer to paramyxoviruses isolated from ducks and gooses than to Lasota strainPart II: Cloning and sequencing of complete F genome of Duck Paramyxo virus Shandong strains.Six paramyxovirus isolates were obtained from lungs, livers and brains of ducks.The The result of RT-PCR showed that isolatesSDFCH,SDTA,SDDY,SDBZH,SDJN,SDWF were velogenic strains of NDV.Then the F fusion gene of those isolates were sequenced.A phylogenetic tree based on published sequences of NDV reference strains were constructed and showed that isolates belong to the genotypeâ…¥NDV.