Progression of lesions in the respiratory tract of broilers after single infection with Escherichia coli compared to superinfection with E-coli after infection with infectious bronchitis virus
Progression of lesions in the respiratory tract of broilers after single infection with Escherichia coli compared to superinfection with E-coli after infection with infectious bronchitis virus
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DOI：
10.1016/j.vetimm.2008.09.019
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发表时间：
2009-01-15
影响因子：
1.8
通讯作者：
Landman, Wil J. M.
中科院分区：
文献类型：
--
作者：
Dwars, R. Marius;Matthijs, Mieke G. R.;Landman, Wil J. M.
研究了4周龄商品肉用仔鸡呼吸道中大肠埃希氏菌病变的进展。病变是在单一的气管内感染大肠杆菌之后，以及在5天前由强毒M41毒株或H120疫苗毒株的眼鼻和气管内传染性支气管炎病毒(IBV)感染之后。对气管、肺和胸气囊病变进行大体和显微检查。分别于接种后3h、接种后1d、2d、4d和7d取材。用免疫组织化学方法检测两种病原体的位置。单独接种大肠杆菌可引起肺炎和气囊炎；如果在感染IBV之前，也可发现同样的肉眼病变和病毒性气管炎。在肺部炎症反应方面，单独感染和双重感染的鸡之间没有明显差异，在7天内消失，但双重感染的鸡存在更多的滤泡。在次级支气管和气囊中检测到IBV抗原，最高可达2dpi，在气管中也可检测到IBV抗原。在化脓性物质、旁支气管壁和气囊内的气管腔内发现了呼叫菌。在肺组织中发现高达4dpi的大肠杆菌抗原。在单一接种和双重接种的禽类中，在肺部是否存在大肠杆菌方面没有明显的差异。在气囊中，从0.5hpi到4dpi，在大肠杆菌和IBV-E中发现了少量细菌。大肠杆菌接种禽类。虽然这两种病原体在7dpi时都被清除了，但在IBV-E中。与只接种大肠杆菌的肉鸡相比，接种了大肠杆菌的禽类在气囊中的病变持续存在。本研究表明，4周龄肉鸡对气管内接种大肠杆菌没有抵抗力，但能在短时间内克服诱导的大肠杆菌感染。此外，先前感染疫苗或强毒IBV似乎不会损害大肠杆菌在肉鸡呼吸道的清除，而只是在气囊中诱导过度的炎症反应，这似乎是野外商业家禽气囊炎模式背后的机制。(C)2008爱思唯尔B.V.保留所有权利。
The progression of Escherichia coli lesions was studied in the respiratory tract of 4-week-old commercial broilers. Lesions were induced after a single intratracheal E. coli infection, and after an infection with E. coli preceded 5 days earlier by an oculo-nasal and intratracheal infectious bronchitis virus (IBV) infection of either the virulent M41 strain or the H120 vaccine strain. Trachea, lung and thoracic airsac lesions were examined macroscopically and microscopically. Tissue samples were taken at 3 h post-inoculation (hpi), and 1, 2, 4 and 7 days post-inoculation (dpi) with E. coli. The location of both pathogens was assessed by immunohistochemistry. Single E. coli inoculation induced pneumonia and airsacculitis; in case it was preceded by IBV infection, the same macroscopical lesions and also viral tracheitis were found. No clear difference existed between the single and dual infected birds with respect to inflammatory reactions in the lung, which had disappeared within 7 days, except for the presence of more follicles in dual infected birds. IBV antigen was detected in secondary bronchi and airsacs up to 2 dpi and in the trachea up too dpi. E. call bacteria were found in the tracheal lumen included in purulent material, the parabronchi and airsacs. In lung tissue E. coli antigen was found up to 4 dpi. No clear difference existed between single and dual inoculated birds regarding the presence of E. coli in the lung. In the airsacs, a few bacteria were found from 0.5 hpi up to 4 dpi in E. coli and IBV-E. coli inoculated birds. Although both pathogens were cleared beyond detection at 7 dpi, in IBV-E. coli inoculated birds lesions in the airsac persisted, in contrast to broilers inoculated with E. coli only. In the present study it is shown that 4-week-old broilers are not resistant to intratracheal E. coli inoculation, however, these birds can overcome the induced E. coli infection within a short time span. Moreover, a preceding infection with vaccine or virulent IBV does not seem to impair the clearance of E. coli in the respiratory tract of broilers, but rather induces an exaggerated inflammatory response in the airsacs only, which seems to be the mechanism behind the pattern of airsacculitis in commercial poultry in the field. (C) 2008 Elsevier B.V. All rights reserved.