Abstract
Enterohaemorrhagic Escherichia coli (EHEC) O157:H7 can use serious diarrhea and haemolytic uremic syndrome. Various factors including adhesins contribute to pathogenesis of EHEC. Previous studies suggested that yadK gene, which encodes a putative fimbrial adhesin in EHEC, may be involved in response of EHEC to acid stress. To characterize role of yadK protein in the pathogenesis of EHEC, recombinant yadK protein was generated and used to immunize rabbit to obtain anti-yadK antiserum, which was able to specifically recognize over-expressed yadK protein in EHEC. Western blotting with anti-yadK revealed a higher level of yadK expression in EHEC under acid adapted-acid stress compared to EHEC under unstressed conditions, which confirmed earlier yadK mRNA studies and indicated that yadK is upregulated in EHEC under acid stress. Finally, we observed that anti-yadK antiserum was able to specifically reduce adhesion of acid stressed EHEC to human epithelial cells compared to adhesion level of unstressed EHEC.
Highlights
Escherichia coli (E. coli) is commonly found in the environment
The Polymerase Chain Reaction (PCR) products were obtained with the use of yadK/BamHIF and yadK/XhoIR specific primers and subjected to agarose gel electrophoresis. 1: 1 kb Ladder (Band size from top to bottom: 10kb, 8kb, 6kb, 5kb, 4kb, 3kb, 2kb, 1kb, 0.5kb) 2-16: PCR product amplified from plasmid extraction of single colonies of DH5α/pGEX-4T3-yadK. 17: PCR product amplified from Negative control. 18: PCR product amplified from Positive Control (EDL933 genomic DNA)
An earlier mRNA microarray study has revealed that a variety of genes encoding virulent factors in Escherichia coli (EHEC) were increased in response to the acid stress[3]
Summary
Escherichia coli (E. coli) is commonly found in the environment. Most E. coli strains are harmless to humans; some strains, such as enterohaemorrhagic E. coli O157:H7 (EHEC O157:H7), present a major threat to human health primarily through food or water contamination. Unlike most commensal strains of E. coli, EHEC disrupts the physiological balance of resident flora in the gastrointestinal (GI) tract. EHEC infection can cause serious bloody or non-bloody diarrhea and haemolytic uremic syndrome (HUS) in human patients[1]. The 1982 outbreaks of EHEC O157:H7 infection in the United States of America posed a serious problem to the public health. A recent EHEC O104:H4 outbreak in Europe has been reported to infect more than 2400 people[2]
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