Characterization of a putative pathogenicity island from bovine Staphylococcus aureus encoding multiple superantigens
Characterization of a putative pathogenicity island from bovine Staphylococcus aureus encoding multiple superantigens
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DOI：
10.1128/jb.183.1.63-70.2001
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发表时间：
2001-01-01
影响因子：
3.2
通讯作者：
Smyth, CJ
中科院分区：
文献类型：
--
作者：
Fitzgerald, JR;Monday, SR;Smyth, CJ
以往的研究表明，从奶牛乳房炎中分离的部分金黄色葡萄球菌同时产生中毒性休克综合征毒素（TSST）和葡萄球菌肠毒素C（SEC）。在这项研究中，一个这样的菌株，RF 122的分子遗传学分析，揭示了一个15,891 bp的推定的致病性岛（SaPIbov）编码的基因TSST（tst），SEC牛的变体（sec-牛），和一个基因（sel），编码肠毒素样蛋白的存在。这个岛包含21个开放阅读框，指定了超过60个氨基酸的假设蛋白质，包括整合酶样基因。该元件在左右连接处以74 bp的同向重复序列为界，整合位点位于S.在金黄色葡萄球菌染色体上，SaPIbov含有与先前表征的tst致病岛SaPI 1（J.A.林赛等人，Mel. Microbiol，29：527-543，1998），具有相同的多位点酶电泳类型、随机扩增多态性DNA类型和核糖体类型的密切相关的菌株RF 120不包含岛，这意味着该元件是移动的并且最近发生了插入/缺失事件。S.的TSST和TSST/SEC缺陷突变体。金黄色葡萄球菌菌株RF 122通过等位基因置换构建。通过野生型菌株和tst和sec-牛等位基因置换突变体的培养上清液进行的体外牛VP特异性淋巴细胞扩增分析显示，TSST刺激BTB 13特异性T细胞，而SEC-牛刺激BTB 93特异性T细胞。这表明SaPIbov的存在可能有助于调节牛免疫应答。
Previous studies have demonstrated that a proportion of Staphylococcus aureus isolates from bovine mastitis coproduce toxic shock syndrome toxin (TSST) and staphylococcal enterotoxin C (SEC). In this study, molecular genetic analysis of one such strain, RF122, revealed the presence of a 15,891-bp putative pathogenicity island (SaPIbov) encoding the genes for TSST (tst), the SEC bovine variant (sec-bovine), and a gene (sel) which encodes an enterotoxin-like protein. The island contains 21 open reading frames specifying hypothetical proteins longer than 60 amino acids including an integrase-like gene. The element is bordered by 74-bp direct repeats at the left and right junctions, and the integration site lies adjacent to the 3' end of the GMP synthase gene (gmps) in the S. aureus chromosome, SaPIbov contains a central region of sequence identity with the previously characterized tst pathogenicity island SaPI1 (J. A. Lindsay et al,, Mel. Microbiol, 29:527-543, 1998), A closely related strain, RF120, of the same multilocus enzyme electrophoretic type, random amplified polymorphic DNA type, and ribotype, does not contain the island, implying that the element is mobile and that a recent insertion/deletion event has taken place. TSST and TSST/SEC-deficient mutants of S. aureus strain RF122 were constructed by allele replacement. In vitro bovine VP-specific lymphocyte expansion analysis by culture supernatants of wild-type strains and of tst and sec-bovine allele replacement mutants revealed that TSST stimulates BTB13-specific T cells whereas SEC-bovine stimulates BTB93-specific T cells. This suggests that the presence of SaPIbov may contribute to modulation of the bovine immune response.