Genome biology of staphylococcal enterotoxin family

近年来，许多新的葡萄球菌肠毒素(Ses)被报道。已知某些SE基因与可移动的遗传元件相关，如致病岛、原噬菌体和质粒。这些事实表明，超抗原性毒素基因在葡萄球菌菌株之间水平转移。有可能这些可移动的遗传元件在金黄色葡萄球菌作为病原体的进化过程中发挥了重要作用。为了研究这些新发现的葡萄球菌超抗原性毒素基因的病原学和流行病学，我们开展了如下研究：1.建立了一套完整的葡萄球菌超抗原毒素基因检测系统，该系统采用4套多重聚合酶链式反应。分析毒素基因与编码可移动遗传元件图谱的毒素基因之间的关系，提示它可能作为编码移动…的毒素基因组合在确定金黄色葡萄球菌超抗原性毒素基因类型中的作用。更多的遗传因素。随后，我们利用PFGE/Southern方法研究了编码SE的新型致病岛。我们发现SEB编码岛至少分为3类。2.利用转座组学方法测定了SED、SELJ和SELJ编码质粒p196的完整核苷酸序列。该质粒编码青霉素抗性操纵子和CD抗性操纵子，以及三种SE(SE1)基因。3.我们鉴定了一种新的葡萄球菌肠毒素(SE)样推定毒素SE1R和SE1P。SE1R蛋白具有显著的T细胞刺激活性。SER刺激T细胞需要MHC-II类分子。丝氨酸刺激T细胞表达受体Vβ3、11、12、13.2和14。这些结果表明丝氨酸是一种超抗原。当给药浓度为0.4 pm或更高时，SE1P可诱导人T细胞产生大量的增殖反应和产生细胞因子IL-2、EFN-γ、肿瘤坏死因子-α和IL-4。辅助性细胞表面MHC-II类分子的表达是SE1P刺激T细胞的必要条件。SE1P选择性地刺激大量携带Vβ5.1、6、8、16、18和21.3受体的人T细胞。这些结果表明，SE1P是一种超抗原。在家中麝鼠的催吐试验中，SE1P被证明是呕吐的，尽管剂量相对较高。我们研究了无超抗原活性的无毒突变体SEC(Msec)免疫是否能保护金黄色葡萄球菌的感染。无超抗原性的mSEC免疫对金黄色葡萄球菌的感染具有保护作用，这种保护作用可能是通过诱导IL-10和IL-4诱导和下调干扰素-γ以及SEC中和抗体来实现的。此外，我们还证明了葡萄球菌SEA诱导人肠上皮细胞内钙离子([Ca^&lt；2+&gt；]i)增加，[Ca^&lt；2+&gt；]i从细胞内储存中释放出来。较少

In recent years, many new staphylococcal enterotoxins (SEs) have been reported. It has been known that certain SE genes are associated with mobile genetic elements such as pathogenicity islands, prophages, and plasmids. These facts imply that superantigenic toxin genes are transferred horizontally between staphylococcal strains. There is a possibility that these mobile genetic elements have played an important role in the evolution of S.aureus as a pathogen. To investigate pathobiology and epidemiology of these newly identified SEs, we had undertaken studies shown hi below.1.We have developed a comprehensive detection system for 18 kinds of classical and newly described staphylococcal superantigenic toxin genes using four sets of multiplex PCR. Analysis of the relationship between toxin genotypes and toxin genes encoding profiles of mobile genetic elements suggests its possible role in determining superantigenic toxin genotypes in S.aureus as combinations of toxin gene-encoding mobile … More genetic elements. Subsequently, we investigated new type of SE-encoding pathogenicity islands using PFGE/southern method. We have found that SEB-encoding islands are classified into at least 3 groups.2.We have determined complete nucleotides sequence of sed, selj and selj encoding plasmid, p196,using transposomics strategy. This plasmid is encoding penicillin resistance operon and Cd-resistance operon, in addition to three kinds of SE (SE1) genes.3.We characterized a novel staphylococcal entertoxin (SE)-like putative toxin SE1R and SE1P. The SE1R protein showed significant T cell stimulation activity. MHC class II molecules were required for T cell stimulation by SER. SER stimulated T cells bearing receptors Vβ 3,11,12,13.2, and 14. These results suggested that SER acts as a superantigen. SE1P induced a substantial proliferative response and the production of cytokines IL-2,EFN-γ,TNF-α, and IL-4 from human T cells when administered at a concentration of 0.4 pM or more. The expression of MHC class II molecules on accessory cells was required for T cell stimulation by SE1P. SE1P selectively stimulated a vast number of human T cells bearing receptors Vβ 5.1,6,8,16,18, and 21.3. These results indicated that SE1P acts as a superantigen. SE1P proved to be emetic in the house musk shrew emetic assay, although at a relatively high dose. We investigated whether immunization with non-toxic mutant SEC (mSEC), devoid of superantigenic activity, can protect against S.aureus infection. Immunization with mSEC devoid of superantigenic properties provides protection against S.aureus infection and the protection might be mediated by the IL-10 and IL-4 induction and down-regulation of IFN-γ, as well as SEC neutralizing antibodies. Also, we demonstrate that staphylococcal SEA induces an increase in intracellular calcium ([Ca^<2+>]i) in human intestinal epithelial cells and the [Ca^<2+>]i is released from intracellular stores. Less