重组禽流感病毒(H5+H7)二价灭活疫苗(H5N1 Re-8株+H7N9 H7-Re1株)对商品肉鸡的免疫效力研究

The protection efficacy of H5/H7 avian influenza inactivated vaccine in commercial broilers

为评估重组禽流感病毒(H5+H7)二价灭活疫苗(H5N1 Re-8株+H7N9 H7-Re1株)对商品肉鸡的免疫保护效果,本研究将该疫苗按照现地免疫程序分别接种10日龄白羽肉鸡和14日龄黄羽肉鸡,疫苗接种前和接种后每周采血,分离血清,检测H5亚型Re-8株和H7亚型H7-Re1株禽流感病毒(AIV)HI抗体滴度,并在初次免疫后3周和出栏时以鼻腔感染方式分别进行攻毒试验。结果显示,免疫前,所有肉鸡血清中H7亚型H7-Re1株AIV HI抗体滴度均低于1log2,H5亚型Re-8株AIV平均HI抗体滴度分别为5.3log2(白羽肉鸡)和4.1log2(黄羽肉鸡);一次免疫的白羽肉鸡在免疫后3周至出栏时,2种亚型AIV平均HI抗体滴度在6.0log2~6.7log2;2次免疫的黄羽肉鸡在初次免疫后3周至出栏时,2种亚型AIV平均HI抗体滴度均在6.0log2以上。在一次免疫后3周时和出栏时,采用高致病性H5、H7亚型AIV攻毒后,对照组白羽肉鸡和黄羽肉鸡均全部死亡,免疫组白羽肉鸡和黄羽肉鸡均不发病、不排毒、不死亡,获得100%的免疫保护。本研究结果表明,重组AIV二价灭活疫苗对商品肉鸡具有良好的免疫效果,为该疫苗的现地应用提供了参考依据。

To evaluate the protection efficacy of H5/H7 (Re-8 strain+H7-Re1 strain) avian influenza inactivated vaccine in broilers, 10 days old white-feather broilers and 14 days old yellow-feather broilers were inoculated with the vaccine according to the field immunization procedures. The sera were collected in the experimental chickens before vaccination and each week after vaccination for HI antibody detection. At 3 weeks post vaccination (p.v.) and pre-slaughter, the broilers were challenged intranasally with 100LD50 of H5N1 and H7N9 viruses, respectively. The results showed that before immunization, the HI antibody titers to H7-Re1 strain were below 1log2 and the mean HI antibody titers to H5 Re-8 strain were 4.1log2 and 5.3log2 in white and yellow feather broilers, respectively. After the white-feather broilers were inoculated with one single dosage (0.5mL) of the vaccine, the mean HI antibody titers to H5 Re-8 strain and H7-Re1 strain ranged from 6.0log2 to 6.7log2 between 3 weeks p.v. and pre-slaughter. After the yellow-feather broilers were given two doses of the vaccine inoculation, the mean HI antibody titers to H5 Re-8 strain and H7-Re1 strain between 3 weeks after the first vaccination and pre-slaughter were all above 6.0log2. After challenged with the H5N1 and H7N9 viruses at 3 weeks p.v. and pre-slaughter, all the vaccinated white-feather and yellow-feather broilers survived without virus shedding and clinical signs during the 10 days observation period, while all the broilers in the control groups died within 5 days post challenge. These results indicated that the H5/H7 vaccine could induce effective immune response in commercial broilers and provided reference information for the application of the vaccine in the field.