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首页> 外文期刊>Poultry Science >Salmonella Typhimurium oral challenge model in mature broilers: Bacteriological, immunological, and growth performance aspects
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Salmonella Typhimurium oral challenge model in mature broilers: Bacteriological, immunological, and growth performance aspects

机译：肉鸡沙门氏菌口服挑战模型：细菌学，免疫学和生长性能方面

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In this study, Salmonella enterica serovar Typhimurium challenge models were tested to identify the best conditions under which to perform the experimental infection of 3-wk-old broilers. Such a model would be useful to study the efficiency of therapeutic treatments that could take place at the end of the grow-out period. Salmonella-free chicks were obtained from a breeder flock vaccinated with Salmonella. Intestinal maternal immunity was monitored by ELISA analyses at 2, 9, and 16 d of age. Data indicated that protection of maternal origin was not maintained over time and was drastically reduced at 9 d of age (P < 0.01). At 21 d of age, chickens were orally inoculated with Salmonella Typhimurium. The effects of the oral challenge dose (0, 3 x 10(3), 3 x 10(6), and 3 x 10(9) cfu/bird) and vancomycin pretreatment (no administration or 25 mg/bird) on intestinal immune responses, growth performance, and Salmonella colonization of chickens were investigated. After infection, the mucosal immune response was rapid, with increased (P < 0.01) anti-Salmonella Typhimurium IgA titers measured at 8 d postinfection in intestinal contents. A linear relationship (P < 0.05) existed between specific IgA levels in intestinal and cecal contents and the challenge dose inoculated. None of the challenge protocols caused mortality or clinical symptoms after infection. Nevertheless, the experimental infection induced a significant deterioration of growth performance. The pretreatment with 25 mg of vancomycin at 3 h before Salmonella inoculation was able to establish stable infection rates among the population of 3-wk-old infected chickens. Nevertheless, Salmonella shedding was not stable over the rearing period, and the bacteria seemed to be naturally eliminated from most birds at 22 d postinfection. This natural clearance of the gut, which was related, at least in part, to the intestinal immune response, should limit the usability of the created mature challenge model within 1 to 2 wk after inoculation.
机译：在这项研究中，测试了沙门氏菌血清型鼠伤寒沙门氏菌攻击模型，以确定进行3周龄肉鸡实验性感染的最佳条件。这样的模型将有助于研究在成年期结束时可能发生的治疗效果。不含沙门氏菌的雏鸡是从接种了沙门氏菌的种鸡群中获得的。通过ELISA分析在2、9和16 d龄时监测肠道母体免疫力。数据表明，随着时间的流逝，对产妇的保护一直没有得到维持，并且在9 d时就大大降低了（P <0.01）。在21 d大时，给鸡口服鼠伤寒沙门氏菌。口服激发剂量（0、3 x 10（3），3 x 10（6）和3 x 10（9）cfu /鸟）和万古霉素预处理（不给药或25 mg /鸟）对肠道免疫的影响研究了鸡的反应，生长性能和沙门氏菌定植。感染后，粘膜免疫反应迅速，在感染后第8天在肠道内容物中测得的抗鼠伤寒沙门氏菌IgA滴度增加（P <0.01）。肠和盲肠内容物中特定的IgA水平与接种的激发剂量之间存在线性关系（P <0.05）。挑战方案均未引起感染后的死亡率或临床症状。然而，实验性感染导致生长性能显着下降。在沙门氏菌接种前3小时用25 mg万古霉素进行预处理，能够在感染3周龄的鸡群中建立稳定的感染率。然而，沙门氏菌在饲养期间的脱落并不稳定，并且似乎在感染后22 d从大多数鸟类中自然消除了细菌。肠道的这种自然清除至少部分与肠道免疫反应有关，应将所建立的成熟攻击模型的可用性限制在接种后的1至2周内。

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