Isolation And Identification Of NDV Local Epidemic Strains And The Comparison Of Vaccination Programs

Newcastle disease (ND) is an acute, highly contiguous infectious disease caused by Newcastle disease virus (NDV). ND was an important disease in poultry production from 1926. Recent years, Outbreak of ND reports were less with vaccination, but the situations of atypical symptom ND were reported in layer chicken and broiler, which were inoculated over and over again, or which were high antibody level. The research on isolation, identification, sequence analysis and genotyping of epidemic strains, were good to show the law of the strains variation. In addition, there were of great value reference to improve prevention and control program of ND, based on the variation strains to select and improve Immune procedure.Firstly, the subject was about Observation on Cytopathologic changes Induced in allantoic fluid of 10d's SPF of the chick embryo by samples, which were doubtful of NDV in Guangxi. The allantoic fluid was taken with HA, and the positives were taken with HI and RT-PCR. The results were 11 samples had HI price, be taken by positive Serum of ND, but not be taken by Avian Influenza's. The samples were amplified by reverse transcription polymerase chain reaction (RT-PCR) about 362bp Special target lane, so,11 strains of NDV were isolated.Besides, the sample was determined by MDT and ICPI. The result was the same with RT-PCR, which was built by identification of NDV virulence GXY0803,GXY0903 and GXY0904 were endogen strain, GXN0709,GXN0710,GXN0711,GXN0712,GXN0713,GXG1003,GXG 1004,GXY1011 were violent strain. The gene F of The strains was Cloned and sequenced, the results were showed that the sequence of F Protein Schizolysis Site of GXN0710,GXN0711,GXN0712,GXN0713,GXN0709,GXG 1003,GXG1004 and GXY1011 was 112R/K-R-Q-K/R-R-F117, had the feature of the velogenic strain, Identity analysis of nucleotide and amino acid sequences showed that the identities between the strains were 95.5-99.9%, were 94.1%-96.9% between NDV gene DQ485260 and GXC1 in GenBank, and were 83.4-84.9% between the three strain of La Sota. Phylogentic tree of the strains were geneⅦsubtype d; The sequence of F Protein Schizolysis Site of GXY0803,GXY0903 and GXY0904 was 112G/E-K/R-Q-G/E-R-L117, had the feature of the lentogenic strain, Identity analysis of nucleotide and amino acid sequences showed that the identities between the three strains were 99.7-99.9%, were 99.7-99.9% between Clone30 and La Sota. Phylogentic tree of the strains were gene VII velogenic strain, which were DQ485260 and GXC1 were 84.6-84.9%; Phylogenetic tree of DQ485260 and GXC1 belong to geneⅡ. Finally, two immune procedures were be made, trial one:Al was 1 does ND+IB live vaccine drop eye in 5d and 10d,0.4 does ND kill vaccine neck injection in 10d,2does ND I kill vaccine muscle injection. Moreover, A2 was 2 does ND+IB live vaccine drop eye and nose in 5d, A3 and A4 were 0.66 does ND kill vaccine (GALLIMUNE) from MERIAL in 5d. A4 removed ND I kill vaccine muscle injection in 20d, A12 was control with no ND vaccine; trial two: B1 and A1 were the same, with general immune procedure, moreover, B3 was 2 does ND+IB live vaccine drop eye and nose in 5d, and removed ND I kill vaccine muscle injection in 20d, B5 and B7 were autologous ND kill vaccine in 5d,B7 removed ND I kill vaccine muscle injection in 20d, B9 was control with no ND vaccine. The serum of All trial chicken was taken in 5d,14d,21d,28d,35d,42d,49d,56d,63d,70d (trial two was 66d), detected by HI antibody and ELISA antibody, challenged by velogenic strain F48E9 and GXC1 in14d,28d,42d,56d (trial two was 14d,28d,35d,66d). The trials showed that, the antibody of the control with no ND vaccine declined from 14d to 35d,close to 0, the rate of protection of challenge was o. The vaccine group with 2 lentogenic vaccine and 2 velogenic vaccine, had same antibody line and same protection of challenge, were 80% mostly in14d,100% in 28d.The study has demonstrated that the isolated virulent strains were belong to gene groupⅦsubtype d. The RT-PCR was a quick, accurate, low cost method for virus nucleotide, against the risk of live virus pollution. The trial was determined by different Immune procedures, and showed the procedure that 2 lentogenic vaccine and 2 velogenic vaccine, were better with against the challenge of velogenic strain, more secure and less immune stress.