ABSTRACT
Enteroaggregative Escherichia coli (EAggEC) are an important cause of diarrhea. Four types of AAF have been identified; however, their prevalence and association with virulence properties remain unclear. E. coli strains carrying the aggR gene as EAggEC that were isolated in Japan and Thailand (n = 90) were examined for AAF subunit genes, two toxin genes (pet/astA), and clump formation. The most prevalent AAF gene was hdaA (28%), followed by aafA (20%), aggA (12%), and agg3A (4%), as well as a putative new AAF sequence (25.6%). Retention status of the toxin genes and intensities of clump formation appeared to vary according to the AAF type.
Subject(s)
Bacterial Adhesion , Escherichia coli Infections/microbiology , Escherichia coli Proteins/metabolism , Escherichia coli/isolation & purification , Fimbriae, Bacterial/metabolism , Trans-Activators/metabolism , Escherichia coli/classification , Escherichia coli/genetics , Escherichia coli/physiology , Escherichia coli Proteins/genetics , Fimbriae, Bacterial/genetics , Humans , Japan , Thailand , Trans-Activators/genetics , Virulence Factors/genetics , Virulence Factors/metabolismABSTRACT
Enteropathogenic Escherichia coli (EPEC) strains produce a bundle-forming pilus (BFP) that mediates localized adherence (LA) to intestinal epithelial cells. The major structural subunit of the BFP is bundlin, which is encoded by the bfpA gene located on a large EAF plasmid. The perA gene has been shown to activate genes within the bfp operon. We analyzed perA gene polymorphism among typical (eae- and bfpA-positive) EPEC strains isolated from healthy and diarrheal persons in Japan (n=27) and Thailand (n=26) during the period 1995 to 2007 and compared this with virulence and phenotypic characteristics. Eight genotypes of perA were identified by heteroduplex mobility assay (HMA). The strains isolated in Thailand showed strong autoaggregation and had an intact perA, while most of those isolated in Japan showed weak or no autoaggregation, and had a truncated perA due to frameshift mutation. The degree of autoaggregation was well correlated with adherence to HEp-2 cells, contact hemolysis and BFP expression. Our results showed that functional deficiency due to frameshift mutation and subsequent nonsense mutation in perA reduced BFP expression in typical EPEC strains isolated in Japan.
Subject(s)
Enteropathogenic Escherichia coli/classification , Escherichia coli Proteins , Repressor Proteins , Amino Acid Sequence , Bacterial Adhesion , Cell Line , Diarrhea/microbiology , Enteropathogenic Escherichia coli/genetics , Enteropathogenic Escherichia coli/metabolism , Enteropathogenic Escherichia coli/pathogenicity , Epithelial Cells/microbiology , Escherichia coli Infections/microbiology , Escherichia coli Proteins/chemistry , Escherichia coli Proteins/genetics , Escherichia coli Proteins/metabolism , Fimbriae Proteins/chemistry , Fimbriae Proteins/genetics , Fimbriae Proteins/metabolism , Gene Expression Regulation, Bacterial , Hemolysis , Heteroduplex Analysis , Humans , Japan , Molecular Sequence Data , Mutation , Phylogeny , Polymorphism, Genetic , Repressor Proteins/chemistry , Repressor Proteins/genetics , Repressor Proteins/metabolism , Sequence Analysis, DNA , Serotyping , Thailand , VirulenceABSTRACT
We developed a quick genetic approach to screen variants of the intimin gene (eae) by using a heteroduplex mobility assay (HMA) that targets the 5' conserved region of eae. The eae variants were categorized into 4 major HMA types and 10 minor subtypes.
