Thomson Daniel U, Loneragan Guy H, Thornton Ashley B, Lechtenberg Kelly F, Emery Daryl A, Burkhardt Doug T, Nagaraja Triuvoor G
Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas 66506, USA.
Foodborne Pathog Dis. 2009 Sep;6(7):871-7. doi: 10.1089/fpd.2009.0290.
To quantify the efficacy of a siderophore receptor and porin (SRP) proteins-based vaccine on the burden of Escherichia coli O157:H7 in feedlot cattle.
Two research trials were conducted in field conditions. In each trial, cattle (n = 1252 in trial #1; n = 1284 in trial #2) were systematically divided into 20 pens and were administered either the E. coli O157 SRP vaccine or a placebo (trial #1: days 0 and 21; trial #2: days 0, 21, and 42). Rectal fecal samples were collected on day 0, and pen floor samples were collected on days 21, 35, 70, and 85 for trial #1 and on days 42 and 98 for trial #2. On day 85 of trial #1, rectoanal mucosal swab samples and hide swab samples were collected. Cattle were weighed on days 0, 21, and 85 (trial #1) or 1 week before harvest (trial #2).
In trial #1, prevalence of E. coli in the feces was lower in vaccinates compared to control animals (p = 0.04). On day 85, the likelihood of an animal being positive at any site was less among vaccinates than controls (p = 0.02). In trail #2, vaccination with SRP was associated with reduced shedding by 85.2% on day 98 (p < 0.01) but not on days 0 or 42. Vaccination with SRP was associated with a 98.2% reduction in concentration of E. coli O157 in fecal samples (2.54 vs. 0.80 log MPN/g of feces; p < 0.01). Cattle performance was not affected by SRP administration.
The E. coli O157:H7 SRP-based vaccine might serve as a preharvest intervention to reduce the burden of E. coli O157:H7 on cattle presented for harvest.
量化一种基于铁载体受体和孔蛋白（SRP）蛋白的疫苗对饲养场牛群中大肠杆菌O157:H7负荷的影响。
在田间条件下进行了两项研究试验。在每项试验中，牛（试验1中n = 1252；试验2中n = 1284）被系统地分为20个栏，并分别接种大肠杆菌O157 SRP疫苗或安慰剂（试验1：第0天和第21天；试验2：第0天、第21天和第42天）。试验1在第0天采集直肠粪便样本，在第21天、第35天、第70天和第85天采集栏舍地面样本；试验2在第42天和第98天采集栏舍地面样本。在试验1的第85天，采集直肠肛门黏膜拭子样本和皮张拭子样本。试验1在第0天、第21天和第85天对牛称重；试验2在屠宰前1周对牛称重。
在试验1中，接种疫苗的牛粪便中大肠杆菌的流行率低于对照动物（p = 0.04）。在第85天，接种疫苗的动物在任何部位呈阳性的可能性低于对照动物（p = 0.02）。在试验2中，接种SRP疫苗与第98天粪便排菌量减少85.2%相关（p < 0.01），但在第0天或第42天无此关联。接种SRP疫苗与粪便样本中大肠杆菌O157浓度降低98.2%相关（2.54对0.80 log MPN/g粪便；p < 0.01）。牛的生长性能不受SRP疫苗接种的影响。
基于大肠杆菌O157:H7 SRP的疫苗可作为宰前干预措施，以减轻待宰牛群中大肠杆菌O157:H7的负荷。
