Department of Experimental and Clinical Pharmacology, College of Pharmacy, Medical School University of Minnesota, Minneapolis, Minnesota 55455, USA.
Biochemistry. 2011 Aug 23;50(33):7157-67. doi: 10.1021/bi200435n. Epub 2011 Jul 21.
Pulsed-field gel electrophoresis (PFGE) clonal type USA200 is the most widely disseminated Staphylococcus aureus colonizer of the nose and is a major cause of toxic shock syndrome (TSS). Exoproteins derived from these organisms have been suggested to contribute to their colonization and causation of human diseases but have not been well-characterized. Two representative S. aureus USA200 isolates, MNPE (α-toxin positive) and CDC587 (α-toxin mutant), isolated from pulmonary post-influenza TSS and menstrual vaginal TSS, respectively, were evaluated. Biochemical, immunobiological, and cell-based assays, including mass spectrometry, were used to identify key exoproteins derived from the strains that are responsible for proinflammatory and cytotoxic activity on human vaginal epithelial cells. Exoproteins associated with virulence were produced by both strains, and cytolysins (α-toxin and γ-toxin), superantigens, and proteases were identified as the major exoproteins, which caused epithelial cell inflammation and cytotoxicity. Exoprotein fractions from MNPE were more proinflammatory and cytotoxic than those from CDC587 due to high concentrations of α-toxin. CDC587 produced a small amount of α-toxin, despite the presence of a stop codon (TAG) at codon 113. Additional exotoxin identification studies of USA200 strain [S. aureus MN8 (α-toxin mutant)] confirmed that MN8 also produced low levels of α-toxin despite the same stop codon. The differences observed in virulence factor profiles of two USA200 strains provide insight into environmental factors that select for specific virulence factors. Cytolysins, superantigens, and proteases were identified as potential targets, where toxin neutralization may prevent or diminish epithelial damage associated with S. aureus.
脉冲场凝胶电泳（PFGE）克隆型 USA200 是鼻腔中传播最广泛的金黄色葡萄球菌定植者，也是中毒性休克综合征（TSS）的主要原因。这些生物体衍生的外蛋白被认为有助于它们的定植和引起人类疾病，但尚未得到很好的描述。从流感后 TSS 肺部和月经阴道 TSS 中分别分离到的两个代表性金黄色葡萄球菌 USA200 分离株 MNPE（α-毒素阳性）和 CDC587（α-毒素突变体）进行了评估。使用生物化学、免疫生物学和基于细胞的测定法，包括质谱法，鉴定了负责对人阴道上皮细胞产生促炎和细胞毒性活性的菌株的关键外蛋白。两种菌株都产生了与毒力相关的外蛋白，细胞溶解素（α-毒素和γ-毒素）、超抗原和蛋白酶被鉴定为主要的外蛋白，它们导致上皮细胞炎症和细胞毒性。由于 MNPE 外蛋白部分中 α-毒素的浓度较高，因此比 CDC587 更具促炎和细胞毒性。尽管在密码子 113 处存在终止密码子（TAG），但 CDC587 仍产生少量的α-毒素。对 USA200 株 [金黄色葡萄球菌 MN8（α-毒素突变体）]的进一步外毒素鉴定研究证实，MN8 尽管存在相同的终止密码子，但也产生低水平的α-毒素。两种 USA200 菌株的毒力因子谱差异为特定毒力因子的选择提供了深入了解环境因素。细胞溶解素、超抗原和蛋白酶被鉴定为潜在的靶标，毒素中和可能预防或减少与金黄色葡萄球菌相关的上皮损伤。
