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如致病性岛、噬菌体和质粒有关。这些事实表明，超抗原毒素基因在葡萄球菌菌株之间水平转移。有一种可能性是，这些可移动的遗传元素在金黄色葡萄球菌作为病原体的进化中发挥了重要作用。为了调查这些新发现的SEs的病理生物学和流行病学，我们进行了如下研究1。利用4套多重PCR技术建立了18种葡萄球菌超抗原毒素基因的综合检测系统。毒素基因型与毒素基因编码移动遗传元件谱的关系分析表明，它可能作为毒素基因编码移动遗传元件的组合，在确定金黄色葡萄球菌超抗原毒素基因型中起作用。随后，我们利用PFGE/southern方法研究了新型se编码致病性岛。我们发现seb编码岛至少可分为3类。我们利用转座体策略确定了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。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蛋白表现出显著的T细胞刺激活性。MHC II类分子是SER刺激T细胞所必需的。SER刺激T细胞携带受体Vβ 3、11、12、13.2和14。这些结果表明SER作为一种超抗原。当给药浓度为0.4 pM或更高时，SE1P诱导了大量的增殖反应，并从人T细胞中产生细胞因子IL-2、EFN-γ、TNF-α和IL-4。辅助细胞上MHC II类分子的表达是SE1P刺激T细胞所必需的。SE1P选择性地刺激大量携带受体Vβ 5.1、6、8、16、18和21.3的人T细胞。这些结果表明SE1P作为一种超抗原。SE1P在麝香鼩催吐试验中被证明是催吐的，尽管剂量相对较高。我们研究了用无超抗原活性的无毒突变型SEC （mSEC）免疫是否能预防金黄色葡萄球菌感染。无超抗原特性的mSEC免疫对金黄色葡萄球菌感染具有保护作用，其保护作用可能与IL-10和IL-4诱导、IFN-γ下调以及SEC中和抗体介导有关。此外，我们证明葡萄球菌SEA诱导人肠上皮细胞细胞内钙（[Ca^<2+>]i）的增加，并且[Ca^<2+>]i从细胞内储存中释放。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