Elanco Animal Health, BU Food Animals, Plantijn en Moretuslei 1, 3rd floor, 2018 Antwerpen, Belgium; Faculty of Veterinary Medicine, Department of Reproduction, Obstetrics and Herd Health, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
Faculty of Veterinary Medicine, Department of Nutrition, Genetics and Ethology, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
J Dairy Sci. 2020 Jul;103(7):6692-6697. doi: 10.3168/jds.2019-17799. Epub 2020 Apr 22.
The objective of the present study was to evaluate the efficacy of a J-5 Escherichia coli vaccine in a mild to moderate inflammatory challenge model using primiparous dairy cows for inoculation only. We hypothesized a clinical difference between placebo and J-5 E. coli vaccinated animals with the mild to moderate inflammatory challenge model. In case the null hypothesis could not be confirmed, the alternate hypothesis was no clinical difference between both treatment groups. Therefore, 23 primiparous cows in mo 7 of pregnancy were randomly assigned to 1 of 2 treatment groups: J-5 E. coli vaccine (n = 12) or placebo (n = 11). Animals were vaccinated 3 times at 56 (±7) and 28 (±7) d before expected calving date and within 14 d postcalving (DIM 5 ± 3). All cows were challenged by infusion with E. coli P4:O32 into 2 left mammary quarters between 14 and 28 d postparturition, at least 10 d after the 3rd vaccination, immediately after the morning milking. Clinical observations and blood and milk samples were collected at several time points from 7 d pre-challenge until 13 d post-challenge. Primiparous cows responded mild to moderately to intramammary E. coli challenge with little clinical difference between treatment groups. Rectal temperature increased earlier in the vaccinated animals, which also eliminated bacteria faster during the early hours after intramammary E. coli challenge. At post-infusion hour 9, the bacterial population was significantly lower in the infected quarters of the vaccinated animals. Blood leukocyte number was only numerically higher in the vaccinated animals, in combination with a numerically higher percentage of late immature polymorphonuclear leukocytes (band cells) in circulation. Even in the nonvaccinated animals, the E. coli challenge in the primiparous cows elicited only a mild to moderate response. The absence of a pronounced clinical difference between vaccinated and nonvaccinated animals was therefore not surprising.
本研究的目的是评估 J-5 大肠杆菌疫苗在仅接种初产奶牛的轻度至中度炎症挑战模型中的功效。我们假设在轻度至中度炎症挑战模型中，安慰剂和 J-5 大肠杆菌接种动物之间存在临床差异。如果不能证实无效假设，则替代假设是两组治疗之间没有临床差异。因此，23 头处于妊娠第 7 个月的初产奶牛被随机分配到 2 个治疗组之一：J-5 大肠杆菌疫苗（n = 12）或安慰剂（n = 11）。动物在预计分娩日期前 56（±7）和 28（±7）天以及分娩后 14 天内（产后第 5 ± 3 天）进行 3 次接种。所有奶牛均在产后第 14 至 28 天内通过向 2 个左侧乳腺象限输注大肠杆菌 P4：O32 进行挑战，至少在第 3 次接种后 10 天，在早晨挤奶后立即进行。在挑战前 7 天至挑战后 13 天，从几个时间点采集初产奶牛的临床观察、血液和奶样。初产奶牛对乳腺内大肠杆菌挑战的反应轻度至中度，治疗组之间几乎没有临床差异。接种动物的直肠温度升高较早，在乳腺内大肠杆菌挑战后最初几小时内也更快地消除细菌。在输注后 9 小时，接种动物感染乳房象限的细菌数量明显较低。接种动物的血液白细胞数仅在数值上较高，同时循环中晚期未成熟多形核白细胞（带状细胞）的百分比也在数值上较高。即使在未接种疫苗的动物中，大肠杆菌挑战也仅引起初产奶牛轻度至中度反应。因此，接种和未接种动物之间没有明显的临床差异并不奇怪。
