中文摘要：

目的 探讨空肠弯曲菌CheA和CheY调控细菌体外趋化和体内定植中的作用及其机制.方法 分别以pET42a和E.coli BL21DE3为表达载体和表达宿主菌,构建空肠弯曲菌NCTC11168株cheA和cheY基因原核表达系统.制备重组表达的rCheA和rCheY兔抗血清并用DEAE-52离子交换法提取其IgG.采用pBiuescript-Ⅱ-SK构建自杀质粒,制备cheA基因敲除的cheA-突变株.采用基于脱氧胆酸钠硬琼脂法（DOC-HAP）的空肠弯曲菌体外趋化模型,检测cheA-突变株趋化能力的变化,同时分别观察rCheA-IgG和氯氰碘柳胺钠对细菌趋化的抑制作用.采用rCheA-IgG和CheY-IgG捕获法,测定DOC作用后空肠弯曲菌CheA和CheY磷酸化水平变化.采用小鼠感染模型比较cheA-突变株和野生株定植能力的差异.结果 所构建的原核表达系统能有效表达rCheA和rCheY.PCR和测序结果证实eheA-突变株染色体DNA中cheA基因被敲除.cheA-突变株丧失对DOC的趋化能力,rCheA-IgG和氯氰碘柳胺钠均对空肠弯曲菌野生株趋化有明显的抑制作用（P〈0.05）.在DOC作用下,空肠弯曲菌野生株CheA和CheY磷酸化水平迅速下降（P〈0.05）.cheA-突变株定植小鼠空肠的能力也明显不如野生株（P〈0.05）.结论 CheA/CheY组成了空肠弯曲菌趋化相关二元信号传导系统（Che-TCSS）,两者均去磷酸化被激活.Che-TCSS中CheA在空肠弯曲菌体外趋化和体内定植中发挥了关键作用,可作为研发抗空肠弯曲菌感染新药的靶标.

英文摘要：

Objective To determine the effects of Che A and CheY proteins of Campylobacter jejuni regulating the bacterial chemotaxis in vitro and colonization in vivo. Methods By using pET42a plasmid and E. coli BL21DE3 as expression vector and expression strain, respectively, prokaryotic expression systems of cheA and cheY genes of C. jejuni strain NCTC11168 was constructed. Rabbits were immunized with the target recombinant expression proteins, rCheA and rCheY, to prepare the antisera. rCheA-IgG and rCheY-IgG in the antisera were separated using DEAE-52 ion exchange column. pBluescript- II -SK was applied to construct suicide plasmid which used to generate cheA gene knock-out mutant （cheA-）. A chemotaxis model in vitro of C. jejuni based on DOC-HAP, the chemotactic ability of cheA＇ mutant as well as the effect of rCheA-IgG and closantel inhibiting the bacterial chemotaxis were demonstrated. The phosphorylation levels of CheA and CheY after DOC treatment were examined by using either rCheA-IgG or CheY-IgG capture method. The difference of colonization ability between cheA- mutant and wild-type of C. jejuni in mice were checked and then compared. Results The constructed prokaryotic expression systems could efficiently express rCheA and rCheY. The data from PCR and sequencing confirmed the cheA gene knock out from cheA- mutant chromosome. cheA- mutant lost its chemotactic ability towards DOC. Both the rCheA-IgG and closantel could inhibit the chemotaxis of wild-type of C. jejuni （P 〈 0.05 ）. When treatment of DOC, the phosphorylation levels of CheA and CheY in wild-type of C. jejuni rapidly decreased （P 〈 0. 05 ）. The colonization ability in murine jejunum of cheA- mutant was also lower than that of the wild-type （ P〈0.05 ） . Conclusion Chemotaxis-associated two-component signaling system （Che-TCSS） of C. jejuni are composed of CheA and CheY, and the two proteins are activated by dephosphorylation. CheA in the Che-TCSS play a critical role in chemotaxis in vitro and colonization in vivo of C. jeju