The Genomes Of Two Field Ndv Were Sequenced And The Quantity Changes Of These Viruses In CEF And Spf Embroyed Eggs During Passages Were Analyzed

Newcastle disease(ND)was caused by Newcastle disease viruses(NDV),which cause high mortality rate and pose a major threat to the avian species worldwide particularly to domestic poultry. Four panzootics of ND have occurred since the first recognition of the disease, and novel genotype appeard in every outbreak. At present in most countries the poultry flock is protected by the vaccine . ND breakouts in the vaccined poultry flocks. In the beginning of the ND breakouts NDV infected only domestic avian species.Warterfowl such as geese was not infected even by virulent strain, or developed only in apparent infection. In 1997 ,a new infectious disease producing high morbidity and mortality among geese breakout in many provinces of China,which was caused by NDV. At present the NDV strains from Warterfowl show high similarrities to the strain from domestic avian species. It is important to prevent ND in the waterfowl.In this study, one virus strain (named ck/CH/LSD/08-29) was isolated from fowls immuned with NDV vaccine which exhibit neurosymptom in Shan Dong province in China in 2008. It was demonstrated a Newcastle disease virus (NDV) with HA and HI assay. According to the published genome sequences of NDV on GenBank, 14 primers were designed and the genome of the isolated ck/CH/LSD/08-29 strain which was passaged 1 times in embryonated eggs was amplified and sequenced by RT-PCR. The NDV isolate (ck/CH/LSD/08-29) was purified by forming plaques in chicken embryo fibroblast(CEF)cell cultures. The complete genome of 5 virus clone were sequenced after purification. It is different between the complete genome of the virus isolate from embryonated eggs and from CEF. It indicated two NDV strains infected fowls initially. The pathogenicity,immunogenicity and tissue tropism of virus may changes by serial passaging in different hosts. The initial virus isolate was passaged in the embryonated eggs and CEF. The every passage′s partial genome were amplified and sequenced into detect the variation of virus passaged in the embryonated eggs and CEF.Phylogenetic tree was constructed based on the nucleotide 389 nucleotides of the F gene of ck/CH/LSD/08-29 strain and ck/CH/LSD/08-29(CEF) with the other NDV strains. That demonstrated ck/CH/LSD/08-29 strain belonged to genotypeⅡ, ck/CH/LSD/08-29(CEF) belonged to genotypeⅦ. Ck/CH/LSD/08-29(CEF) strain showed high similarrities to 5 NDV strains from waterfowl. Because of it the initial host of strain maybe is waterfowl. While ck/CH/LSD/08-29 strain showed high similarrities to a artificial NDV recombinant. The recombinant contained the fusion(F) and hemagglutinin-neuraminidase(HN) glycoprotein gene of the genotypeⅦNDV isolate and a lentogenic LaSota strain of the NDV. Phylogenetic tree constructed based on 6 genes of the strain indicated ck/CH/LSD/08-29 strain showed high nucleotides homology with the velogenic NDV basde the F and HN gene, while the strain showed high nucleotides homology with a lentogenic LaSota strain of the NDV based the NP and P gene. The variation of the two strains passaged in the embryonated eggs and CEF was detected by amplifying the partial genome of them. The result showed the strain ck/CH/LSD/08-29(CEF) disappeared as the mix virus was passaged 6 times in CEF. The strain ck/CH/LSD/08-29 disappeared as the mix virus was passaged 11 times in embryonated eggs. The amino acid sequences of the two strains were compared. The amino acid sequences of the two strain′s HN protein were the same, while the amino acid sequences of the two strain′s NP,P and L protein distinct largely. NP,P and L proteins maybe relate to the tissue tropism of virus.This study fulfilled the biological information database of NDV. The quantity variation of virus were passaged in the embryonated eggs and CEF were compared. The relation of host tropism and genes of NDV was analyzed.