Quorum sensing system in Helicobacter pylori infection

luxS突变体（HP 06）是通过PCR扩增的luxS：：cat基因从TN 2 DNA片段（Drs Ogura和贝格的馈赠）自然转化到H. pylori TK 1402菌株。使用哈氏弧菌BB 170菌株（来自Bassler博士的礼物）通过发光生物测定评价AI-2的产生。luxS基因。pylori在E.结果表明，TK 1402株luxS基因与已报道的26695株和J 99株luxS基因的同源性分别为96.1%和96.2%，并对1uxS突变株HP 06进行了生物学特性分析。突变株HP 06的AI-2产量约为原株TK 1402的1/100。虽然HP 06和TK 1402菌株之间的耐酸能力和对胃上皮细胞的粘附活性没有显著差异，但HP 06的运动性明显弱于TK 1402。约10^9CFU的H. pylori感染蒙古沙土鼠（MGS/Sea，雄性，8周龄），间隔24小时，经口接种2次。H.感染后1个月，1/5的HP 06感染沙鼠经RT-PCR检测到pylori。H. RT-PCR检测所有感染TK 1402的沙土鼠（n=5）的pylori。实验结果表明，感染TK 1402的沙鼠胃粘膜出现了严重的炎症反应。pylori对H.幽门螺杆菌感染的实验研究luxS突变体的感染性降低可能与运动性降低有关。

The luxS mutant (HP06) was generated by natural transformation of PCR-amplified luxS::cat gene from TN2 DNA fragment (kind gift from Drs Ogura & Berg) into H. pylori TK1402 strain. The production of AI-2 was evaluated by luminescence bioassay using Vibrio harveyi BB170 strain (kind gift from Dr Bassler). luxS gene of H. pylori could be expressed in E. coli, and genome sequence of the luxS from TK1402 strain was shown to have 96.1% and 96.2% homology to that of luxS of two reported strains 26695 and J99 strains, respectively.Microbiological characteristics of 1uxS mutant HP06 strain was analyzed. The production of AI-2 by HP06 mutant was nearly one-hundredth of that by TK1402 parent strain. Although there was no significant difference in acid-resistance and adhesion activity to gastric epithelial cells between HP06 and TK1402 strains, the motility of HP06 was significantly weaker than that of TK1402. Approximately, 10^9CFU of H. pylori were orally inoculated into Mongolian gerbil (MGS/Sea, male, 8wk) twice with 24 hr-interval. H. pylori was detected by RT-PCR in 1 out of 5 HP06-infected gerbils at 1 month after infection. In contrast, H. pylori was detected by RT-PCR in all the TK1402-infected gerbils (n=5). Severe inflammation in gastric mucosa was observed only in TK1402-infected gerbil.These results indicate that quorum sensing in H. pylori is important for colonization of H. pylori in gastric mucosa of Mongolian gerbil. The decrease of infectivity by luxS mutant was implied to be associated with the decreased motility.