A riboflavin auxotroph of Actinobacillus pleuropneumoniae is attenuated in swine
A riboflavin auxotroph of Actinobacillus pleuropneumoniae is attenuated in swine
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DOI：
10.1128/iai.64.11.4659-4664.1996
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发表时间：
1996-11-01
影响因子：
3.1
通讯作者：
Mulks, MH
中科院分区：
文献类型：
--
作者：
Fuller, TE;Thacker, BJ;Mulks, MH
胸膜肺炎放线杆菌是一种传染性很强的猪胸膜肺炎的病原体。通过删除核黄素生物合成操纵子的一部分，代之以编码卡那霉素抗性的基因盒，构建了胸膜肺炎沙门氏菌1型需要核黄素的突变体AP233。受影响的基因包括核黄素合成酶的α和β亚基，以及含有GTP环水合酶和3，4-二羟基-2-丁酮-4-磷酸合成酶活性的双功能酶。AP233在没有外源核黄素的情况下不能生长，但在其他方面与亲本野生型菌株相同。对猪的实验感染研究表明，根据死亡率、肺部病理和临床体征，需要核黄素的突变体在剂量高达野生亲本正常50%致死剂量的500倍时不会致病。这是通过在代谢基因中引入明确的突变来首次证明胸膜肺炎杆菌的减毒作用，也首次证明核黄素生物合成所需基因的突变可以导致细菌病原体的减毒。
Actinobacillus pleuropneumoniae is the etiological agent of a highly contagious and often fatal pleuropneumonia in swine. A riboflavin-requiring mutant of A. pleuropneumoniae serotype 1, designated AP233, was constructed by deleting a portion of the riboflavin biosynthetic operon (ribGBAH) and replacing it with a gene cassette encoding kanamycin resistance. The genes affected included both the alpha- and beta-subunits of riboflavin synthase as well as a bifunctional enzyme containing GTP cyclohydrase and 3,4-dihydroxy-2-butanone-4-phosphate synthase activities. AP233 was unable to grow in the absence of exogenous riboflavin but otherwise was phenotypically identical to the parent wild-type strain. Experimental infection studies with pigs demonstrated that the riboflavin-requiring mutant was unable to cause disease, on the basis of mortality, lung pathology, and clinical signs, at dosages as high as 500 times the normal 50% lethal dose for the wild-type parent. This is the first demonstration of the attenuation of A. pleuropneumoniae by introduction of a defined mutation in a metabolic gene and the first demonstration that mutations in the genes required for riboflavin biosynthesis can lead to attenuation in a bacterial pathogen.