Pathological and immunohistochemical in- vestigations in rainbow trout (Oncorhynchus mykiss Walbaum, 1792) experimentally in- fected with Vibrio anguillarum
Pathological and immunohistochemical in- vestigations in rainbow trout (Oncorhynchus mykiss Walbaum, 1792) experimentally in- fected with Vibrio anguillarum
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发表时间：
2012
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通讯作者：
H. Avci;S. B. Lu;H. Çaǧırgan
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作者：
H. Avci;S. B. Lu;H. Çaǧırgan
本研究的目的是调查和比较的临床，病理和免疫组化观察虹鳟鱼实验感染鳗弧菌根据接种途径（腹腔注射与浸泡）的数据。为此，对20条鱼腹膜内接种5.5 × 107 cfu鳗弧菌血清型O 1，并将其他20只动物暴露于50 mL稀释于水（30 L）中的细菌接种物（5.5 × 105 cfu/mL）30分钟，而对2组对照鱼（每组n = 8）进行类似操作，仅暴露于溶媒。每天记录死亡率和临床体征，并对自发死亡或杀死的鱼进行尸检，使用常规染色进行组织病理学检查，并使用靶向鳗弧菌抗原的多克隆鸡抗体进行免疫组织化学检查。死亡率为55%时，鳟鱼腹腔内接种和40%时，他们暴露于细菌浸泡。大多数死亡分别发生在第3天至第9天和第5天至第11天。与水肿相关的充血和出血主要在皮肤、肌肉和鳃中观察到，在腹腔内接种鳟鱼的内脏器官（肝脏、心脏、脾脏、胃）和腹部脂肪组织中观察到的程度较低。组织学研究也证实了病变的性质，并证明了与细菌团块相关的细胞变性和坏死，以及鳃和胃中嗜酸性粒细胞（EGC）和脱粒的增加。在鳟鱼浸泡接种，类似的，但较温和的病变，观察到少数受感染的鱼，除了鳃病变系统存在，以及标记。仅在疾病的急性期（例如，根据接种途径直至第15天和第11天）观察到损伤组织中对细菌抗原的免疫阳性。这些结果清楚地表明，鳗弧菌在虹鳟鱼的致病性，主要是在腹腔内接种后，并建议在浸泡期间的鳃可能是细菌进入的主要网站。
The objectives of the study were to investigate and to compare the clinical, pathological and immunohistochemical data observed in rainbow trouts experimentally infected with Vibrio anguillarum according to the inoculation route (intraperitoneal injection vs. immersion). For that, 20 fishes were intraperitoneally inoculated with 5.5x10 7 cfu V. anguillarum serotype O1 and 20 other animals were exposed to 50 mL of bacterial inoculum (5.5x105 cfu/mL) diluted in water (30 L) for 30 minutes whereas 2 groups of control fishes (n = 8 in each group) were similarly manipulated and only exposed to the vehicle. Mortality and clinical signs were daily recorded and necropsy, histopathology using conventional staining and immunohistochemistry using polyclonal chicken antibodies targeted against the V. anguillarum antigens were performed on fishes spontaneously died or killed. Mortality rates were 55% when trouts were inoculated intraperitoneally and 40% when they were exposed to bacteria by immersion. The majority of deaths have occurred between the 3rd and the 9th days and between the 5th and the 11th days, respectively. Hyperaemia and haemorrhages associated to oedema were predominantly observed in skin, muscles and gills, and at a lesser extend in visceral organs (liver, heart, spleen, stomach) and in the abdominal fat tissues in intraperitoneally inoculated trouts. Histopathological investigations have also confirmed the nature of the lesions and have also evidenced cellular degeneration and necrosis associated to bacteria clumps as well as the increase in eosinophilic granular cells (EGCs) and degranulation in gills and in stomach. In trouts inoculated by immersion, similar but milder lesions were observed on a smaller number of infected fishes except that the gill lesions were systematically present and well marked. Immunopositivity to bacterial antigens in injuried tissues was observed only during the acute phase of the disease (e.g. until the 15th and the 11th days according to the inoculation route). These results clearly demonstrate the pathogenecity of V. anguillarum in rainbow trouts mainly after intraperitoneal inoculation and suggest that gills during immersion may be the primary site of the bacterium entry.