Fox J Trent, Thomson Daniel U, Drouillard James S, Thornton Ashley B, Burkhardt Doug T, Emery Daryll A, Nagaraja T G
Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, Kansas, USA.
Foodborne Pathog Dis. 2009 Sep;6(7):893-9. doi: 10.1089/fpd.2009.0336.
Escherichia coli O157 is a foodborne pathogen commonly isolated from beef cattle feces and can enter the food chain at harvest. A relatively new vaccine technology uses the iron requirement of pathogenic bacteria by targeting the siderophore receptor and porin proteins (SRP). We evaluated the efficacy of an anti-E. coli O157 SRP-based vaccine in feedlot cattle naturally shedding the organism. Sixty cattle were selected from an original population of 600; 50 of these were fecal positive for E. coli O157 on two occasions and the remaining 10 animals were fecal positive on one occasion. Cattle were stratified based on the results of screening samples and randomly allotted to one of three treatment groups: control, vaccinated with 2 mL per animal of E. coli SRP vaccine, or vaccinated with 3 mL per animal of E. coli SRP vaccine subcutaneously 21 days apart. Control cattle were injected with sterile saline emulsified with an adjuvant. Fecal samples and rectoanal mucosal swab samples were collected two or three times a week for 8 weeks to monitor shedding of E. coli O157. Prevalence of the pathogen was analyzed by repeated measures on animals over weeks. The SRP vaccine at the 3 mL dose reduced prevalence of E. coli O157 compared to the control (17.7% vs. 33.7%; p < 0.01). A similar trend was observed with the 2 mL dose (29.1%), but differences were not statistically significant compared to control (p = 0.40). Additionally, the 3 mL dose of SRP vaccine reduced the number of days cattle tested culture positive for E. coli O157 (p = 0.05) and the number of days cattle were identified as high-shedders (p = 0.02) compared to control.
大肠杆菌O157是一种常见于肉牛粪便中的食源性病原体，在收获时可进入食物链。一种相对较新的疫苗技术通过靶向铁载体受体和孔蛋白蛋白（SRP）来利用病原菌对铁的需求。我们评估了一种基于抗大肠杆菌O157 SRP的疫苗在自然排出该病原体的饲养场牛中的疗效。从600头牛的原始群体中选出60头牛；其中50头牛两次粪便检测大肠杆菌O157呈阳性，其余10头牛一次粪便检测呈阳性。根据筛查样本的结果对牛进行分层，并随机分配到三个治疗组之一：对照组、每头动物皮下注射2 mL大肠杆菌SRP疫苗、或每头动物皮下注射3 mL大肠杆菌SRP疫苗，间隔21天。对照组牛注射用佐剂乳化的无菌盐水。每周收集两到三次粪便样本和直肠肛门黏膜拭子样本，持续8周，以监测大肠杆菌O157的排出情况。通过对动物数周的重复测量来分析病原体的流行率。与对照组相比，3 mL剂量的SRP疫苗降低了大肠杆菌O157的流行率（17.7%对33.7%；p<0.01）。2 mL剂量（29.1%）也观察到类似趋势，但与对照组相比差异无统计学意义（p = 0.40）。此外，与对照组相比，3 mL剂量的SRP疫苗减少了牛检测大肠杆菌O157培养阳性的天数（p = 0.05）以及被确定为高排出者的天数（p = 0.02）。
