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Foodborne Pathogens: Hygiene and Safety

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Front. Microbiol. | doi: 10.3389/fmicb.2018.01628

The fimbrial gene z3276 in Enterohaemorrhagic Escherichia coli O157:H7 contributes to bacterial pathogenicity

 Xuehan Zhang1*, Bicheng Zhang1, Xiaohan Sun1, Hongjie Fan2 and Kongwang He1
  • 1Jiangsu Academy of Agricultural Sciences (JAAS), China
  • 2College of Veterinary Medicine, Nanjing Agricultural University, China

Enterohaemorrhagic Escherichia coli (EHEC) O157:H7 is a zoonotic pathogen of worldwide importance that causes foodborne infections in humans. It is not capable of expressing type I fimbrial because of base deletion in the fim operon. BLAST analysis shows that the open reading frame z3276, a specific genetic marker of EHEC O157:H7, encodes a sequence with high amino acid identity to other E. coli type I fimbrial, but its definitive function in EHEC O157:H7 remains unclear. We are here to report that a z3276 mutant (△z3276) was constructed using the reference EHEC O157:H7, the mutant △z3276 was biologically characterized, and the pathogenicity of △z3276 was assessed in mice in comparison with the wild type (WT) strain. Motility and biofilm formation assays revealed a smaller twitching motility zone for △z3276 on the agar surface and significantly decreased biofilm formation by △z3276 compared with the parental strain. The adhesion and invasion ability of △z3276 to HEp-2 cells showed no significant change, but the invasion ability of △z3276 to IPEC-J2 cells was attenuated. Furthermore, in the animal study, we observed shortened and lower fecal shedding among the △z3276 mutant-infected animals compared with those infected WT strain. The data in this study indicate that this unique gene of z3276 in EHEC O157:H7 seems to play an important role in bacterial pathogenicity.

Keywords: EHEC O157:H7, genetic marker, z3276, motility, Biofilm formation, invasion, pathogenicity

Received: 27 Mar 2018; Accepted: 28 Jun 2018.

Edited by:

Giovanna Suzzi, Università degli Studi di Teramo, Italy

Reviewed by:

Amy M. Grunden, North Carolina State University, United States
Baoguang Li, United States Department of Health and Human Services, United States  

Copyright: © 2018 Zhang, Zhang, Sun, Fan and He. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Xuehan Zhang, Jiangsu Academy of Agricultural Sciences (JAAS), Nanjing, China, liuxuehan1996@hotmail.com