Pepe J C, Wachtel M R, Wagar E, Miller V L
Department of Microbiology & Molecular Genetics, University of California at Los Angeles 90095, USA.
Infect Immun. 1995 Dec;63(12):4837-48. doi: 10.1128/iai.63.12.4837-4848.1995.
It has been hypothesized for many years that the ability of Yersinia spp. to invade tissue culture cells is reflective of their ability to penetrate the intestinal epithelium and that this capacity is an important aspect of the disease process. Three different genes from Yersinia spp. that are involved in the tissue culture invasion phenotype have been identified: inv, ail, and yadA. It was previously shown that inv is necessary for efficient penetration of the intestinal epithelium by Yersinia enterocolitica. The present study was initiated to determine whether other known Yersinia invasion factors could promote uptake of the bacteria by mice in the absence of invasion. In addition, the roles of these three invasion factors in the survival of the bacteria, lethality for mice, and development of pathology were compared. We found that YadA is necessary for persistence of Y. enterocolitica in Peyer's patches, and consistent with this observation, the yadA mutant was avirulent for mice infected either orally or intraperitoneally. In addition, the inv yadA double mutant was avirulent. Histological and immunohistological examination of the Peyer's patches of infected mice indicated that despite the presence of large numbers of CFU at 24 h the yadA and ail yadA mutants cause only minimal pathology and recruitment of macrophages. At 42 h postinfection, Peyer's patches from mice infected with the inv mutant showed no pathology, despite the prediction that some of the mice by this time would be colonized. However, at 72 h, inflammation and necrosis were evident in some Peyer's patches. Together, these observations suggest that for visible pathology to develop, a threshold number of bacteria (> 10(5)) is needed and the bacteria need to persist for more than 24 h. Lastly, YadA but not Ail may play a role in the less efficient, delayed invasion of the intestinal epithelium observed for the inv mutant.
多年来一直有人提出假说，认为耶尔森氏菌属侵入组织培养细胞的能力反映了它们穿透肠上皮的能力，且这种能力是疾病进程的一个重要方面。已鉴定出耶尔森氏菌属中与组织培养侵袭表型相关的三个不同基因：inv、ail和yadA。先前已表明，inv对于小肠结肠炎耶尔森氏菌有效穿透肠上皮是必需的。开展本研究以确定在不存在侵袭的情况下，其他已知的耶尔森氏菌侵袭因子是否能促进小鼠对细菌的摄取。此外，还比较了这三种侵袭因子在细菌存活、对小鼠的致死性及病理发展中的作用。我们发现YadA对于小肠结肠炎耶尔森氏菌在派伊尔结中的持续存在是必需的，与此观察结果一致，yadA突变体对经口或腹腔感染的小鼠无致病性。此外，inv yadA双突变体也无致病性。对感染小鼠的派伊尔结进行组织学和免疫组织学检查表明，尽管在24小时时存在大量菌落形成单位，但yadA和ail yadA突变体仅引起最小程度的病理变化和巨噬细胞募集。在感染后42小时，感染inv突变体的小鼠的派伊尔结未显示出病理变化，尽管预计此时一些小鼠会被定植。然而，在72小时时，一些派伊尔结中出现了炎症和坏死。总之，这些观察结果表明，要出现明显的病理变化，需要有阈值数量的细菌（>10⁵），且细菌需要持续存在超过24小时。最后，YadA而非Ail可能在inv突变体观察到的对肠上皮的低效、延迟侵袭中起作用。
