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An atypical weakly haemolytic strain of Brachyspira hyodysenteriae is avirulent and can be used to protect pigs from developing swine dysentery

机译:猪痢疾短螺旋体的非典型弱溶血性菌株是无毒的,可用于保护猪免受猪痢疾的侵害

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The anaerobic intestinal spirochaete Brachyspira hyodysenteriae colonises the large intestine of pigs and causes swine dysentery (SD), a severe mucohaemorrhagic colitis. SD occurs worldwide, and control is hampered by a lack of vaccines and increasing antimicrobial resistance. B. hyodysenteriae strains typically produce strong beta-haemolysis on blood agar, and the haemolytic activity is thought to contribute to the pathogenesis of SD. Recently, weakly haemolytic variants of B. hyodysenteriae have been identified in Europe and Australia, and weakly haemolytic strain D28 from Belgium failed to cause disease when used experimentally to infect pigs. Moreover, pigs colonised with D28 and then challenged with virulent strongly haemolytic strain B204 showed a delay of 2–4?days in developing SD compared to pigs not exposed to D28. The current study aimed to determine whether Australian weakly haemolytic B. hyodysenteriae strain MU1, which is genetically distinct from D28, could cause disease and whether exposure to it protected pigs from subsequent challenge with strongly haemolytic virulent strains. Three experimental infection studies were undertaken in which no diseases occurred in 34 pigs inoculated with MU1, although mild superficial lesions were found in the colon in 2 pigs in one experiment. In two experiments, significantly fewer pigs exposed to MU1 and then challenged with strongly haemolytic virulent strains of B. hyodysenteriae developed SD compared to control pigs not previously exposed to MU1 (p?=?0.009 and p?=?0.0006). These data indicate that MU1 lacks virulence and has potential to be used to help protect pigs from SD.
机译:厌氧肠螺旋体猪痢疾短螺旋体定居在猪的大肠中,并导致猪痢疾(SD),一种严重的粘膜出血性结肠炎。 SD在世界范围内发生,并且缺乏疫苗和增加的抗微生物性阻碍了控制。猪痢疾短螺旋体菌株通常在血琼脂上产生强的β溶血作用,溶血活性被认为有助于SD的发病机理。最近,在欧洲和澳大利亚已经鉴定出猪痢疾短螺旋体的弱溶血变体,比利时的弱溶血性菌株D28在实验上感染猪时未能引起疾病。此外,与未暴露于D28的猪相比,定植于D28然后被强溶血性强毒株B204攻击的猪显示出SD发育延迟了2-4天。目前的研究旨在确定遗传上不同于D28的澳大利亚弱溶血猪痢疾短螺旋体菌株MU1是否会引起疾病,以及暴露于该猪是否能保护猪免受强溶血性强毒株的后续攻击。进行了三项实验性感染研究,其中在34头接种MU1的猪中没有疾病发生,尽管在一项实验中在2头猪的结肠中发现了轻度的浅表皮病变。在两个实验中,与先前未暴露于MU1的对照猪相比,暴露于MU1并随后受到猪痢疾短螺旋体的强溶血性强毒株攻击的猪要少得多(p = 0.009和p = 0.0006)。这些数据表明,MU1缺乏毒力,有潜力用于帮助保护猪免受SD侵害。

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