弯曲杆菌是人类主要的肠病原体。弯曲杆菌表现出比空肠弯曲杆菌更少的遗传多样性,并聚集成三个分支,其中进化枝1包括大多数人类和农场动物分离株,而环境大肠杆菌分离株主要属于进化枝2和进化枝3。最近,我们对从水中培养的八个大肠杆菌进化枝2和3分离株的全基因组进行了测序,在这里,我们研究了它们与人类HT-29结肠癌细胞的相互作用,与临床进化枝1分离株的相互作用。接种后1至2小时,所有C.coli进化枝3分离株已经引起细胞坏死,而进化枝1和2分离株均未分析诱导细胞死亡。进化枝2和3的分离株比进化枝1的分离株更好地粘附在上皮细胞上,但是所有分离株诱导的白细胞介素-8(IL-8)水平相似。翻译的推定毒力基因cadF的比对和系统发育分析,flpA,iama,CIAB,和ceuE揭示进化枝特异性蛋白质序列变异,进化枝1和2序列关系更密切,进化枝3序列距离更远,总的来说。此外,当测量RNA水平时,进化枝3分离株显示出显著较低的cadF表达水平,iama,与进化枝2分离株相比,而进化枝3分离株中flpA表达水平较高。细胞致死性扩张毒素基因也在进化枝2和进化枝3中表达,尽管进化枝之间没有差异。我们的发现证明了大肠杆菌进化枝1、2和3分离株对人类细胞的影响之间的差异,并表明由于观察到的细胞毒性,大肠杆菌进化枝3可能比进化枝2更具毒性。重要性大肠杆菌弯曲杆菌是全球人类胃肠炎的常见人畜共患病原因。大多数感染是由大肠杆菌进化枝1分离株引起的,而由进化枝2和3分离株引起的感染很少见。这是否取决于对人类感染重要的水库中进化枝2和3分离株的低流行率或它们引起人类疾病的较低能力尚不清楚。这里,我们研究了C.coli进化枝2和3分离株对人类细胞系的影响。与临床进化枝1分离株相比,这些分离株粘附于人类细胞的程度更高。此外,我们可以证明大肠杆菌进化枝3分离株快速诱导细胞死亡,表明大肠杆菌毒力的差异细胞死亡的确切机制仍有待揭示,但是选择的基因显示出有趣的进化枝特异性表达模式。
Campylobacter bacteria are major human enteropathogens. Campylobacter coli shows less genetic diversity than C. jejuni and clusters into three clades, of which clade 1 includes most human and farm animal isolates, while environmental C. coli isolates mainly belong to clades 2 and 3. Recently, we sequenced the whole genomes of eight C. coli clade 2 and 3 isolates cultivated from water, and here we studied their interaction with human HT-29 colon cancer cells compared to that of clinical clade 1 isolates. All C. coli clade 3 isolates already caused cell necrosis 1 to 2 h after inoculation, whereas none of the clade 1 and 2 isolates analyzed induced cell death. Isolates from clades 2 and 3 adhered to epithelial cells better than clade 1 isolates, but all isolates induced similar levels of interleukin-8 (IL-8). Alignment and phylogenetic analysis of the translated putative virulence genes cadF, flpA, iamA, ciaB, and ceuE revealed clade-specific protein sequence variations, with clade 1 and 2 sequences being more closely related and clade 3 sequences being further apart, in general. Moreover, when RNA levels were measured, clade 3 isolates showed significantly lower levels of expression of cadF, iamA, and ceuE than clade 2 isolates, while flpA expression levels were higher in clade 3 isolates. The cytolethal distending toxin genes were also expressed in clades 2 and 3, although there was no difference between clades. Our findings demonstrate differences between the effects of C. coli clade 1, 2, and 3 isolates on human cells and suggest that C. coli clade 3 might be more virulent than clade 2 due to the observed cytotoxicity.IMPORTANCECampylobacter coli is a common zoonotic cause of gastroenteritis in humans worldwide. The majority of infections are caused by C. coli clade 1 isolates, whereas infections due to clade 2 and 3 isolates are rare. Whether this depends on a low prevalence of clade 2 and 3 isolates in reservoirs important for human infections or their lower ability to cause human disease is unknown. Here, we studied the effects of C. coli clade 2 and 3 isolates on a human cell line. These isolates adhered to human cells to a higher degree than clinical clade 1 isolates. Furthermore, we could show that C. coli clade 3 isolates rapidly induced cell death, suggesting differences in the virulence of C. coli The exact mechanism of cell death remains to be revealed, but selected genes showed interesting clade-specific expression patterns.