鸡新城疫抗原抗体复合物疫苗的研究

Studies on newcastle disease antigen-antibody complex vaccine

用中等毒力新城疫(ND) Roakin株病毒作为抗原,与ND抗体配制不同比例的复合物,并在37℃感作不同的时间,分别配制复合物疫苗1和复合物疫苗2,用无特定病原菌(SPF)鸡进行免疫对比试验.试验鸡随机分为4组,饲养在隔离器中,除对照组外,试验1、2、3组分别在20日龄接种复合物疫苗1、复合物疫苗2和常规Roakin活疫苗.各组从免疫后第1周起至第7周,每周采血,用HI试验检测血清中ND抗体水平,70日龄时用北京株ND强毒进行攻毒试验.第1、2组在接种疫苗后,有个别鸡出现轻微喘气或羽毛蓬松的症状,2～3d后好转;第3组接种疫苗后,鸡群100%发病,呈典型ND症状,约1周后康复,无鸡只死亡;对照组的鸡群一直保持健康状态.第1、2、3组的抗体水平分别在免疫后的2、3、2周达到高峰,HI效价分别为1∶29、1∶28 5和1∶210,在第7周分别下降为1∶26 07、1∶26 07和1∶27,而对照组的HI效价一直在1∶22左右.攻毒后,对照组死亡率为100%,第1、2、3组分别为13 3%、6 7%和6 7%.试验结果提示:用中等毒力的NDV和ND抗体配制成抗原抗体复合物疫苗,可以大大减轻疫苗的毒副作用,在保持疫苗良好免疫原性的同时,提高了疫苗的安全性.

Complexes composed of antigens of newcastle disease (ND)-Roakin strains and anti-NDV antibodies in different ratios, were respectively incubated at 37 ℃ for different durations of time. When inoculated with the complexes (antigen/antibody:100/25 and 100/37.5,10 h incubation at 37 ℃), no mortality in chicken embryo was observed. SPF chicks were divided into 4 groups and raised in isolation units. Birds in group 1, 2 and 3 were vaccinated when 20-day-old with complex vaccine 1, complex vaccine 2 and Roakin live vaccine, birds in group 4 were not vaccinated with any vaccine. Blood samples were taken every week post-immunization for 7 consecutive weeks. Levels of anti-NDV antibody were tested by HI. All chickens in groups 1,2,3 and 4 were challenged with the velogenic NDV Beijing strain when 70-day-old. The results were: 2 or 3 chicks in group 1 and 2 showed slight respiratory distress with gasping or plumage dishevelment post-vaccination, bot recovered 3 days later; all birds in group 3 showed typical ND symptoms after vaccination, and then recovered 1 week later, no chicks died; birds in group 4 remained healthy during the period before challenge. The mean HI titers of group 1, 2 and 3 was found to peak at 2, 3 and 2 weeks post-vaccination, the values being 1∶2~9, 1∶2^(8.5) and 1∶2^(10) respectively. After challenge, mortality in group 4 was 100%, and that in group 1,2 and 3 respectively were 13.3%, 6.7% and 6.7%. The results suggested that mesogenic strains of NDV vaccine mixed with anti-NDV antibody could reduce vaccine virulence, vaccine prepared from this antigen-antibody complex had a good immunogenicity and safety.