一株肠出血性大肠杆菌O_(157)H_7免疫奶牛实验即抗EHEC O_(157)H_7免疫乳的试制

用1株O157H7菌株和另外11株人类肠道主要病原细菌配制O157H7单菌疫苗和多菌联合多价疫苗,对荷斯坦牛进行免疫实验。对免疫常乳中抗EHEC O157H7特异性抗体凝集价进行了长期监测,并对受试奶牛的免疫反应、应激反应及疫苗对奶牛可能产生的毒性作用进行了观察。结果证明,疫苗免疫效果很好,所有奶牛在整个泌乳期一直保持较高的特异性抗体效价(滴度),均在27以上,下个泌乳期开始阶段也未见明显下降的迹象。本次实验意外发现约有30%的未进行过免疫注射的对照组乳样有较高的O157H7特异性抗体滴度,个别乳样凝集价高达27,这可能说明这些牛群中有较高的O157H7感染率或携带率。O157H7是人类近二十余年来才开始认识到的出血性结肠炎(HC)的主要致病菌,能造成出血性腹泻和其它严重并发症。是值得研究和重点防范的病原细菌。

In this work, water-soluble and W/O emulsion microcapsule vaccines were prepared with sole EHEC O157H7 strainmixed with other 11 pathogenic bacterial strains from the three genera. Namely salmonella, Shigella and Escherichia. Hol-stein cows in their later 2 month of gestation were vaccinated/immunized respectively by prior prepared vaccines, and theagglutination titer of EHEC O157H7 specific antibody in the cows milk with respect to control group was detected through theentire period of lactation and the next lactation. The immunoresponse, clinical symptoms after vaccinating and potential badeffects of the O157H7 vaccines were surveyed. The results indicated that the immunogenic effects of vaccine II( w/o emulsionmicrocapsule vaccine) were remarkablely good, the titers were all above 27, the high anti-O157H7 titer level could sustain to thenext lactation, and no obvious bad effects were observed. Surprisingly, about 30% milk samples in control group had positiveimmunoreactions to the EHEC O157H7, and the highest EHEC O157H7 specific antibody titer was 27 , This kind of phenomenonhas never reported in China yet. EHEC O157H7 is the major pathogen of hemorrhagenic colonitis (HC), the history of outbreaksof the disease in the world wide in recent two decades, as well as the epidemic and clinical feature of the EHEC O157H7caused diarrhea were briefly reviewed.