Characterization of tccP2 carried by atypical enteropathogenic Escherichia coli.
ABSTRACT Atypical enteropathogenic Escherichia coli (EPEC) comprise an important group of paediatric pathogens. Atypical EPEC have reservoirs in farm and domestic animals where they can be either commensal or pathogenic; serogroup O26 is dominant in humans and animals. Central to intestinal colonization by EPEC is the translocation of the type III secretion system effector Tir into enterocytes, which following phosphorylation (Tir-Yp) recruits Nck to activate the N-WASP actin signalling cascade. The authors have recently shown that typical EPEC strains, belonging to the EPEC-2 lineage, carry a tir gene encoding Tir-Yp and can also use the alternative TccP2 actin-signalling cascade. The aim of this study was to determine if tccP2 is found in atypical EPEC isolated from human and farm animals. tccP2 was found at a frequency of 41% in non-O26 EPEC isolates and in 82.3% of the O26 strains. TccP2 of human and animal strains show high level of sequence identity. It is shown that most strains carry a tir gene encoding Tir-Yp. In addition the authors identified two new variants of tir genes in EPEC O104:H12 and NT:H19 strains.
Article: Two atypical enteropathogenic Escherichia coli strains induce the production of secreted and membrane-bound mucins to benefit their own growth at the apical surface of human mucin-secreting intestinal HT29-MTX cells.[show abstract] [hide abstract]
ABSTRACT: In rabbit ligated ileal loops, two atypical enteropathogenic Escherichia coli (aEPEC) strains, 3991-1 and 0421-1, intimately associated with the cell membrane, forming the characteristic EPEC attachment and effacement lesion of the brush border, induced a mucous hypersecretion, whereas typical EPEC (tEPEC) strain E2348/69 did not. Using cultured human mucin-secreting intestinal HT29-MTX cells, we demonstrate that apically aEPEC infection is followed by increased production of secreted MUC2 and MUC5AC mucins and membrane-bound MUC3 and MUC4 mucins. The transcription of the MUC5AC and MUC4 genes was transiently upregulated after aEPEC infection. We provide evidence that the apically adhering aEPEC cells exploit the mucins' increased production since they grew in the presence of membrane-bound mucins, whereas tEPEC did not. The data described herein report a putative new virulence phenomenon in aEPEC.Infection and immunity 03/2010; 78(3):927-38. · 4.21 Impact Factor
Article: Study of polymorphisms in tir, eae and tccP2 genes in enterohaemorrhagic and enteropathogenic Escherichia coli of serogroup O26.[show abstract] [hide abstract]
ABSTRACT: Enteropathogenic (EPEC) and enterohaemorrhagic (EHEC) Escherichia coli are responsible for food poisoning (enteritis and enterotoxaemia) in humans in developed countries. Cattle are considered to be an important reservoir of EHEC and EPEC strains for humans. Moreover, some of the strains, belonging to the O26, O111, O118 serogroups, for example, are also responsible for digestive disorders in calves. The Translocated intimin receptor (Tir), the intimin (Eae) and the Tir-cytoskeleton coupling protein (TccP) represent three virulence factors implicated in the intimate attachment of the bacteria to the eukaryotic cell. Major variants have already been described for these genes among the different serogroups but minor variations have not often been studied. In this study, we examined the polymorphisms of the tir, eae and tccP2 genes of O26 strains (EPEC and EHEC isolated from bovines and from humans) with the aim to determine whether these polymorphisms are host specific or not. Of the 70 tested strains, 10 strains (14% of the strains) presented one or several polymorphisms in the tir and eae genes, which have never previously been described. Concerning tccP2 detection, 47 of the 70 strains (67% of the strains) were found to be positive for this gene. Most of the strains were found to possess tccP2 variants described in strains of serogroup O26. Nevertheless, three strains had tccP2 genes respectively described in strains of serogroup O111, O103 and O55. Moreover, none of the polymorphisms was statistically specific to the bovine or the human isolates. Nevertheless, the two major variants of tccP2 were statistically associated with the pathotype (EPEC or EHEC). In conclusion, tir and eae gene polymorphisms were found not to be numerous and not to be predominantly synonymous. Moreover, no difference was observed between human and bovine strains regarding the presence of polymorphisms. Finally, some tccP2 variants appeared to be pathotype specific. Further investigations need to be performed on a larger number of strains in order to confirm this specificity.BMC Microbiology 01/2011; 11:124. · 3.04 Impact Factor