| Content: Seven viral strains which have heagglutination activity were isolated from 7 chicken flocks with high morbidity and mortality contagious disease. These strains were able to agglutinate chicken red blood cell which could be inhibited by Newcastle disease virus LaSota strain standard antisera, but could not be neutralized by the antisera, and were still able to kill chicken embryos. These strains were confirmed to be Newcastle disease virus based on the test of 50% embryo lethal dose, mean death time of chicken embryos, intracerebral pathogenicity index in 1-day-old chicken, intravenous pathogenicity index in 6-week-old chicken, dehaemagglutination and haemagglutinin heat-stability. The results demonstrated that these strains isolated were high virulent Newcastle disease virus, which were virulent as similar as F48E9 strain.Gene fragment with F protein splitting site of 4 typical NDV strains isolated was amplified by RT-PCR and analyzed by sequences. Maybe one strain was low mortality virus and three strains were high mortality virus according to amino acid sequence of splitting site of gene. The result of the sequencing and comparison of sequence demonstrated that the homogeneity of nucleoside sequence among the 3 high mortality virus strains and Clone30 was 83.6%-84.0%, among typical high mortality F48E9 strain was 86.5-88.3%.The homogeneity of amino acid sequence among the 3 high mortality virus strains and Clone30 was 85.9%-87.0%, among typical high mortality F48E9 strain was 89.1-91.3%. The NDV systemic evolution tree was depicted by MegAlign software and showed that the three high mortality viral strains were gene type VII and the low mortality one was gene type II.The inactivation effect of ethanol extract of propolis on Newcastle Disease virus Clone-30 strain was studied through chicken embryo inoculation. The result demonstrated that, 0.1-10mg/ml ethanol extract of propolis could inactivate NDV clone-30 and the inactivation effect directed ratio the temperature inactivated and concentrate of ethanol and had correlation with the reaction time within 3-30min.Egg embryo from hen which hadn't been immunized were inoculated by NDV Clone-30 strain and virus strain isolated and the antigen was gathered and inactivated with formaldehyde solution and mixed with natural immunity intensifier propolis,so the compositive NDV proplis inactivated vaccine was made successfully. The safety and immunity of vaccines were detected and the result demonstrated that the safety was good when 3-6 week old chicken were immunized through muscle with twice dose; the 15 days growth curve demonstrated the vaccine hadn't bad effect to chicken when they were immunized with one dose and studied the actuate toxicity test. The 3-6 week old chicken were immunized through muscle with one dose used and 10 chicken every batch vaccine, the GMT of HI antibodies of ND in the 5-32 days old chicken sera were 4.8 log2 and 9.81og2,respectively.The result of ND immunity and challenge to chicken demonstrated that every dose of three batches vaccine contain PD50 more than or equal to 131 and 127,respectively. The result of dynamic pathology tissue comparison of muscle injected demonstrated that the effect on the injection tissue of propolis vaccines was apparently less than that of oil vaccines. The immunity period of proplis vaccine was temporary as 6 months, the stored period of this vaccine was more than 18 months in -10℃ and didn't ice up in this temperature, 12 months in 4-8 ℃ and 6 months in 15- 20℃. The result of field test and the effect of immunity 2 billions fowls demonstrated that the vaccine was safe and reliable, meanwhile had good immunity effect.
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