Jansson D S, Råsbäck T, Fellström C, Feinstein R
Department of Animal Health and Antimicrobial Strategies, National Veterinary Institute, Uppsala, Sweden.
J Comp Pathol. 2009 Nov;141(4):211-22. doi: 10.1016/j.jcpa.2009.03.007. Epub 2009 Jul 28.
Brachyspira hyodysenteriae, the aetiological agent of swine dysentery, and a recently proposed and closely related enteropathogenic spirochaete "Brachyspira suanatina", originally isolated from pigs or mallards (Anas platyrhynchos), were used to inoculate week-old mallard ducklings orally or cloacally. The colonization rate, clinical outcome, faecal dry matter content, blood leucocyte counts and gross, microscopical and electron microscopical features 14-16 days post-inoculation were investigated at necropsy examination. Strains of "B. suanatina" of pig and mallard origin and B. hyodysenteriae of mallard origin colonized the ducklings by oral inoculation, and colonization was also established by cloacal inoculation with a "B. suanatina" strain of mallard origin. The porcine reference strain of B. hyodysenteriae (B204) failed to colonize the birds. Unchallenged contact birds in one of the challenge groups were readily colonized by a strain of "B. suanatina" of mallard origin. The proportion of colonized birds differed significantly between the challenge groups (P < 0.0001). For each challenge group, the inoculum and a randomly selected subset of recovered isolates had an identical biochemical profile and banding pattern by randomly amplified polymorphic DNA (RAPD) analysis. None of the birds developed clinical signs of gastrointestinal disease during the trial. The faecal dry weight contents, body weights and total leucocyte and heterophil counts did not differ between the various groups of birds. At the microscopical and electron microscopical levels, the caecal mucosa in some of the Brachyspira culture-positive birds had sharply demarcated epithelial cell changes and there were features of irreversible cell damage in crypt necks coinciding with spirochaetal infiltration of the mucosa. The crypts in Brachyspira culture-positive birds were deeper than in culture-negative birds (median: 237 microm and 218 microm, respectively, P = 0.019). This challenge model was well suited for use in mallards and consistent with previous findings that strongly haemolytic Brachyspira spp. may cross the species barrier between pigs and birds.
猪痢疾密螺旋体（Brachyspira hyodysenteriae）是猪痢疾的病原体，以及一种最近提出的且密切相关的肠道致病性螺旋体“鸭源短螺旋体（Brachyspira suanatina）”，最初从猪或绿头鸭（Anas platyrhynchos）中分离得到，被用于经口或泄殖腔接种1周龄的绿头鸭雏鸭。在尸检时研究了接种后14 - 16天的定植率、临床结果、粪便干物质含量、血液白细胞计数以及大体、显微镜和电子显微镜特征。猪源和鸭源的“鸭源短螺旋体”菌株以及鸭源猪痢疾密螺旋体菌株通过经口接种使雏鸭定植，并且用鸭源“鸭源短螺旋体”菌株经泄殖腔接种也能实现定植。猪痢疾密螺旋体的猪参考菌株（B204）未能使雏鸭定植。其中一个攻毒组中未受攻毒的接触雏鸭很容易被鸭源“鸭源短螺旋体”菌株定植。攻毒组之间定植雏鸭的比例差异显著（P < 0.0001）。对于每个攻毒组，接种物和随机选择的一部分回收分离株通过随机扩增多态性DNA（RAPD）分析具有相同的生化谱和条带模式。在试验期间，没有一只雏鸭出现胃肠道疾病的临床症状。不同组雏鸭的粪便干重含量、体重以及总白细胞和嗜异性粒细胞计数没有差异。在显微镜和电子显微镜水平上，一些猪痢疾密螺旋体培养阳性雏鸭的盲肠黏膜有界限分明的上皮细胞变化，并且隐窝颈部存在不可逆细胞损伤的特征，这与黏膜的螺旋体浸润一致。猪痢疾密螺旋体培养阳性雏鸭的隐窝比培养阴性雏鸭的更深（中位数分别为237微米和218微米，P = 0.019）。这种攻毒模型非常适合用于绿头鸭，并且与先前的研究结果一致，即强溶血的短螺旋体属物种可能跨越猪和鸟类之间的物种屏障。
