牛支原体(新疆株)灭活疫苗的制备及犊牛免疫保护性评价

DEVELOPMENT AND EVALUATION OF INACTIVATED MYCOPLASMA BOVIS VACCINE IN CALVES

为研发用于预防犊牛支原体肺炎及关节炎灭活油佐剂疫苗并评价其免疫效果,本研究采用牛支原体(Mycoplasma bovis,M.bovis)新疆分离株做为制苗菌株,经牛支原体专用液体扩大培养基培养后进行膜分离浓缩、甲醛灭活,加入油佐剂乳化制备牛支原体灭活疫苗,经无菌检验、实验动物安全性检验及乳化效果检测后进行犊牛免疫效果测定。结果显示,免疫组犊牛在二免后14 d,血清中M.bovis抗体达到0.465(OD_(450)),3头攻毒犊牛均保持良好的精神状态且体温变化不明显,临床症状综合评分为3,肺脏解剖学及病理组织学观察无异常,肺脏病变指数为2且肺脏中未分离回收到M.bovis;未免疫对照组犊牛同期血清M.bovis抗体为0.142(OD_(450)),3头攻毒犊牛均先后出现体温升高、轻度咳喘、脓性鼻液、明显消瘦等症状,临床症状综合评分为11,肺脏病变指数为17,肺脏尖叶、心叶及部分膈叶均表现明显肝变,2头犊牛表现胸膜与肺脏黏连,1头犊牛整个尖叶广泛分布黄白色蚕豆状大小坏死性结节,与自然感染病例相同,病理组织学观察显示肺泡腔和支气管中有大量中性粒细胞浸润,支气管管壁充血、水肿,肺脏部分坏死灶呈均质红染,为典型的化脓性及坏死性肺炎变化,从病变肺组织中均分离回收到M.bovis。结果表明,本研究制备的牛支原体灭活疫苗给犊牛免疫后能产生良好的免疫应答反应,并能抵抗M.bovis感染所致的肺脏病变作用。

The objective of the present study was to prepare Mycoplasma bovis vaccine and evaluate its protective immunity in calves.The inactivated M.bovis vaccine was developed using a series of procedures including massive propagation of the bacterial strain isolated from Xinjiang Province in the home-made artificial media,separation and concentration of the cellular membranes,inactivation with formalin and emulsion in oil ajuvant.Then,the vaccine was tested for inactivation,emulsifying effect and safety in calves.The calves were observed for fever and other clinical signs and serological responses for 4 weeks before termination.The vaccine did not cause adverse effects in calves.Post challenge,the vaccinated calves showed few clinical signs while all unvaccinated calves developed pneumonia.There was a significant decrease in body weight in unvaccinated calves as compared to vaccinates but a significant increase in lung lesions and rectal temperatures in unvaccinated calves.In conclusion,the inactivated M.bovis vaccine produced a significant protection against the virulent challenge.