| For the reason of IBD new epidemic situation in the west areas of Henan province, the study had been done on the following respects, in order to control and prevent the epidemic of IBD better.1.The Investigation of IBD Epidemic Situation in the West Areas of Henan ProvinceThe epidemic situation of IBD was investigated during 2000~2003 in the west areas of Henan province (Luoyang, Jiaozuo, Pingdingshan, Nanyang). The results showed that the incidence season of IBD is tendentiously year-round; the incidence range increased largely in the days of chickens; the pathological changes are not typical; the course of disease is longer and the mortality lower; the IBD occurs again and again in one flock of chickens; The infections are higher in the following and the cure rate is lower; the morbidity of immunized chickens is still higher. The incidence reasons have been analyzed simultaneously.2. Isolation and Identification of Epidemic IBDV Strains and Clone Analysis of VP2 Gene of One Strain IBDV in the West Areas of Henan ProvinceThe epidemic IBDV strains isolated from chickens infected with IBD typically in the west areas of Henna province were identified initially, while the VP2 gene was cloned from one virus strain (Luoyang virus strain) and their sequence was analyzed. The results showed that the IBDV isolated are virulent or very-virulent IBDV strains, the antigenicity may have some changes.3. Cultivation of Chicken Embryo-culture and Cell-culture IBDV Strains from Epidemic IBDV Strains in the West Areas of Henan ProvinceThe epidemic IBDV strains in the west areas of Henan province (Luoyang, Jiaozuo, Pingdingshan, Nanyang) were cultivated with chicken embryo and chicken embryo fibroblastic (CEF) cells. The results showed that the epidemic IBDV strains cultivated blindly with chicken embryo, which is cultivated in the third generation through chorion and in the fourth and fifth generation through allantoic cavity are completely chickenembryo-culture virus, ELDso is 10 /0.2mL, this virus can be used as a species virus for chicken embryo cultivation. The chicken embryo-culture IBDV cultivated with CEF cells become CEF cell-culture IBDV strains till fifth generation, the TCID50 is 10-6.18/0.1mL, this virus can be used as a species virus for cell cultivation.4. Preparation and Efficacy Observation of Different IBDV Strains Oil-adjuvant Inactivated Vaccine from Epidemic D3DV Strains in the West Areas of Henan ProvinceThe chickens were infected artificially with epidemic IBDV isolated from that in the west areas of Henan province, the bursa tissue oil-adjuvant vaccine was prepared with bursas of the infected chickens. The chicken embryo-culture and cell-culture IBDV oil-adjuvant inactivated vaccine were prepared by using chicken embryo-culture IBDV strains and CEF cell-culture IBDV strains. The results of efficacy determination showed that the best one is the bursa tissue oil-adjuvant inactivated vaccine, the embryo-culture and the cell-culture IBDV oil-adjuvant inactivated vaccine are as good as the bursa tissue oil-adjuvant inactivated vaccine in immune efficacy and immune protective rate. The chickens challenged with virulent IBDV strains can obtain 100% protection at 60 days post-inoculation with these vaccines.5. Preparation and Efficacy Observation of Different IBDV Strains Proplis-adjuvant Inactivated Vaccine from Epidemic IBDV Strains in the West Areas of Henan ProvinceThe chickens were infected artificially with epidemic IBDV isolated from that in the west areas of Henan province (Luoyang, Jiaozuo, Pingdingshan, Nanyang), the bursa tissue proplis-adjuvamt inactivated vaccine was prepared with bursas of the infected chickens. The chicken embryo-culture and cell-culture IBDV strains proplis-adjuvant inactivated vaccine were prepared by using chicken embryo-culture IBDV strains and CEF cell-culture IBDV strains. The results of efficacy determination showed that the bursa tissue proplis-adjuvant inactivated vaccine is the best one in three of them and the earlier immune efficacy... |
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