Construction and rescue of infectious cDNA clone of pigeon-origin Newcastle disease virus strain JS/07/04/Pi / 病毒学报

Based on the complete genome sequence of pigeon-origin Newcastle disease virus strain JS/07/04/ Pi(genotype VIb), nine overlapped fragments covering its full-length genome were amplified by RT-PCR. The fragments were connected sequentially and then inserted into the transcription vector TVT7/R resulting in the TVT/071204 which contained the full genome of strain JS/07/04/Pi. The TVT/071204 was co-transfected with three helper plasmids pCI-NP, pCI-P and pCI-L into the BSR cells, and the transfected cells and culture supernatant were inoculated into 9-day-old SPF embryonated eggs 60 h post-transfection. The HA and HI tests were conducted following the death of embryonated eggs. The results showed that the allantoic fluids obtained were HA positive and the HA could be inhibited by anti-NDV serum which indicated that the strain JS/07/04/Pi was rescued successfully. The rescued virus rNDV/071204 showed similar growth kinetics to its parental virus in CEF. The successful recovery of this strain would contribute to the understanding of the host-specificity of pigeon-origin NDV and to the development of the novel vaccines against the NDV infection in pigeons.

Biological characteristics and sequence analysis of fusion genes of Newcastle disease virus isolates / 病毒学报

Twenty Newcastle disease virus (NDV) strains were isolated from chickens and geese in the field outbreaks during 2005 and 2006 in some regions of Jiangsu and Guangxi province. Assessment of the virulence by MDT and ICPI, RT-PCR and sequence analysis of fusion protein gene were used to compare the properties of NDV isolates. The results indicated that MDT and ICPI of the isolates were 45.3h - 58.2h and 1.61 - 2.00 respectively, which confirmed that the all NDV isolates were highly virulent. And their hemagglutinin were not resistant to heat and belonged to fast pattern of elution. The results of nucleotide sequencing and phylogentic analysis of fusion protein gene showed that the twenty strains shared homology from 79.7% to 100% among themselves, from 78.1% to 83.4% and from 80.2% to 90.1% with NDV LaSota, F48E8, respectively. The putative amino acid sequences of fusion protein at the cleavage sites of all the isolates were 112R-R-Q-R/K-R-F117, with the motif characteristics of the virulent NDV strain, which was in accordant with the results of assessment of the pathogenicity. The phylogentic tree based on sequences of fusion protein gene variable regions (47-420nt) revealed that the 18 strains belonged to sub-genotype VIId and the others belonged to an old genotype III of NDV, revealing that subgenotype VIId virus was responsible for the NDV outbreaks in some regions of Jiangsu and Guangxi promince recently.

Rescue and Preliminary Application of a Recombinant Newcastle Disease Virus Expressing Green Fluorescent Protein Gene / 中国病毒学

Based on the complete genome sequence of Newcastle disease virus (NDV) ZJI strain,seven pairs of primers were designed to amplify a cDNA fragment for constructing the plasmid pNDV/ZJI,which contained the full-length cDNA of the NDV ZJI strain.The pNDV/ZJI,with three helper plasmids,pCIneoNP,pCIneoP and pCIneoL,were then cotransfected into BSR-T7/5 cells expressing T7 RNA polymerase.After inoculation of the transfected cell culture supernatant into embryonated chicken eggs from specific-pathogen-free (SPF) flock,an infectious NDV ZJI strain was successfully rescued.Green fluorescent protein (GFP) gene was amplified and inserted into the NDV full-length cDNA to generate a GFP-tagged recombinant plasmid pNDV/ZJIGFP.After cotransfection of the resultant plasmid and the three support plasmids into BSR-T7/5 cells,the recombinant NDV,NDV/ZJIGFP,was rescued.Specific green fluorescence was observed in BSR-T7/5 and chicken embryo fibroblast (CEF) cells 48h post-infection,indicating that the GFP gene was expressed at a relatively high level.NDV/ZJIGFP was inoculated into 10-day-old SPF chickens by oculonasal route.Four days post-infection,strong green fluorescence could be detected in the kidneys and tracheae,indicating that the recombinant GFP-tagged NDV could be a very useful tool for analysis of NDV dissemination and pathogenesis.

Effect of Fusion Protein Cleavage Site Mutations of NDV ZJ1 Strain on Its Fusion Activity / 微生物学通报

NDV strain ZJ1 strain , a highly virulent NDV strain, has been prevalent among the waterfowls in China mainland in the past years. Multi-basic amino acid sequence distribute in the protease cleavage site of F protein of this strain. Recombinant expressing plasmid pCI-FT, was generated by converting multi-basic amino acid sequence of 112, 115, 117 of the protease cleavage site of F_ 0 protein, to the non-basic amino acid sequence characteristic of avirulent NDV strain. The result from co-expression of mutant or parental F protein with homologous HN protein in COS-1 cells revealed that both mutant and parental F protein had fusion activity. The result from co-expression of mutant or parental F protein with homologous HN protein in CEF cells showed that the cleavage activity of mutant F protein was significantly reduced. The study built a foundation for mutagenesis of amino acid sequence of the protease cleavage site of F_ 0 protein at the full-length cDNA clone level, study on factors contributing to virulence and construction of candidate vaccine strain, and so on.

Establishment of Reverse Genetics System for NDV Isolated from Goose / 微生物学通报

Eight fragments were amplified and cloned into pCR2.1 vector with the designed primers.The fragments,amplified with primer Ⅰ to Ⅶ,were subcloned into transcription vector to construct the plasmid pNDVZJI which contained the full-length cDNA of NDV ZJI strain.The eukaryotic expression vector pCI-L was constructed by subcloning the fragments,amplified with the primer Ⅴ,Ⅵ and Ⅷ,into the expression vector pCI-neo.The full-length cDNA clone,pNDVZJI,with three helper plasmids,pCI-NP、pCI-P and pCI-L,were cotranfected into BSR-T7/5 cell expressing T7 RNA polymerase.After inoculation of transfected cell culture into embryonated chicken eggs from specific pathogen free(SPF)flock,The NDV of ZJI strain was rescued successfully,which laid a good foundation for the further related research.