Flagellar motility is necessary for Aeromonas hydrophila adhesion

Qin, Yingxue; Lin, Guifang; Chen, Wenbo; Xu, Xiaojin; Yan, Qingpi

doi:10.1016/j.micpath.2016.07.006

Cited by 54 publications

(37 citation statements)

References 30 publications

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“…Bacterial motility, enabled by a lateral or polar flagella, have a number of biological functions in pathogens such as chemotaxis, adhesion, and invasion as seen in E. coli, P. aeruginosa , and Clostridium difficile (Haiko and Westerlund-Wikström, 2013; Qin et al, 2016). A recent study demonstrated that flagellar motility is necessary for A. hydrophila to adhere to the host mucus (Qin et al, 2016).…”

Section: Discussionmentioning

confidence: 99%

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Species Distribution and Prevalence of Putative Virulence Factors in Mesophilic Aeromonas spp. Isolated from Fresh Retail Sushi

2017

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Aeromonas spp. are ubiquitous bacteria that have received increasing attention as human pathogens because of their widespread occurrence in food, especially seafood and vegetables. The aim of this work was to assess the species identity and phylogenetic relationship of 118 Aeromonas strains isolated from fresh retail sushi from three producers, and to characterize the isolates with respect to genetic and phenotypic virulence factors. We also evaluate the potential hazard associated with their presence in ready-to-eat seafood not subjected to heat treatment. Mesophilic Aeromonas salmonicida was most prevalent (74%), followed by A. bestiarum (9%), A. dhakensis (5%), A. caviae (5%), A. media (4%), A. hydrophila (2%), and A. piscicola (1%). All isolates were considered potentially pathogenic due to the high prevalence of genes encoding hemolysin (hlyA) (99%), aerolysin (aerA) (98%), cytotoxic enterotoxin (act) (86%), heat-labile cytotonic enterotoxin (alt) (99%), and heat-stable cytotonic enterotoxin (ast) (31%). The shiga-like toxins 1 and 2 (stx-1 and stx-2) were not detected. Moreover, there was heterogeneity in toxin gene distribution among the isolates, and the combination of act/alt/hlyA/aerA was most commonly detected (63%). β-hemolysis was species-dependent and observed in 91% of the isolates. All A. media and A. caviae strains were non-hemolytic. For isolates belonging to this group, lack of hemolysis was possibly related to the absence of the act gene. Swimming motility, linked to adhesion and host invasion, occurred in 65% of the isolates. Partial sequencing of the gyrB gene demonstrated its suitability as a genetic marker for Aeromonas species identification and for assessment of the phylogenetic relationship between the isolates. The gyrB sequence divergence within a given species ranged from 1.3 to 2.9%. A. bestiarum, A. salmonicida, and A. piscicola were the most closely related species; their sequences differed by 2.7–3.4%. The average gyrB sequence similarity between all species was 93%, demonstrating its acceptable taxonomic resolution. The presence of multiple species of potential pathogenic Aeromonas in fresh retail sushi raises new food safety issues related to the increased consumption of ready-to-eat food composed of raw ingredients.

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Section: Discussionmentioning

confidence: 99%

“…A recent study demonstrated that flagellar motility is necessary for A. hydrophila to adhere to the host mucus (Qin et al, 2016). We were able to demonstrate motility on soft agar plates in a significant proportion of A. salmonicida (71%) and A. hydrophila (100%) isolates, and less in the other species.…”

Section: Discussionmentioning

confidence: 99%

Species Distribution and Prevalence of Putative Virulence Factors in Mesophilic Aeromonas spp. Isolated from Fresh Retail Sushi

2017

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“…While occasional studies proposed that native flagella could not initiate an immune response in a way the FliC monomers did 30, 33 , some other investigations found that intact flagellar filament did initiate this response, or even more efficiently than monomers when at higher doses/concentrations 34–38 . Furthermore, FlgE has been reported to regulate flagellar development, and mutations in this gene caused flagellar deficiency and rotating impairment 10, 12, 13, 39 . Pilot studies showed that mutations with sites B and F, when introduced into PAO1 genome via recombination, impaired assembly of flagella (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…In P. aeruginosa , the flagellar hook is formed by polymerization of approximately 120 single molecules named flagellar hook protein E (FlgE) (NP_249771), encoded by the flagellar hook protein gene, flgE (GeneID: 878285). In addition to providing flexibility and power conversion between the basal body and the filament, FlgE is also involved in the elongation or assembly of the filament, and flgE mutations often result in structural abnormality or deficiency in multiple bacterial species 10–13 . However, additional roles that this protein may play, as either an isolated monomer or a polymer in the hook, remain unclear except for a few reports on the antigenicity of FlgE in bacterial infections 14–16 .…”

Section: Introductionmentioning

confidence: 99%

Flagellar Hooks and Hook Protein FlgE Participate in Host Microbe Interactions at Immunological Level

Shen

Chen

Wang

et al. 2017

Sci Rep

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Host-microbe interactions determine the outcome of host responses to commensal and pathogenic microbes. Previously, two epithelial cell-binding peptides were found to be homologues of two sites (B, aa168–174; F, aa303–309) in the flagellar hook protein FlgE of Pseudomonas aeruginosa. Tertiary modeling predicted these sites at the interface of neighboring FlgE monomers in the fully formed hook. Recombinant FlgE protein stimulated proinflammatory cytokine production in a human cell line and in murine lung organoid culture as detected with real-time RT-PCR and ELISA assays. When administered to mice, FlgE induced lung inflammation and enhanced the Th2-biased humoral response to ovalbumin. A pull-down assay performed with FlgE-saturated resin identified caveolin-1 as an FlgE-binding protein, and caveolin-1 deficiency impaired FlgE-induced inflammation and downstream Erk1/2 pathway activation in lung organoids. Intact flagellar hooks from bacteria were also proinflammatory. Mutations to sites B and F impaired bacteria motility and proinflammatory potency of FlgE without altering adjuvanticity of FlgE. These findings suggest that the flagellar hook and FlgE are novel players in host-bacterial interactions at immunological level. Further studies along this direction would provide new opportunities for understanding and management of diseases related with bacterial infection.

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“…The process of infection includes adhesion, colonization, invasion, proliferation in the host, and the secretion of toxins (Huang et al., ; Wang et al., ). Bacterial adhesion to host surfaces is one of the key steps in the initial infection process (Chen, Yan, Wang, Zhuang, & Wang, ; Luo et al., ), and many pathogens have been shown to develop the ability to adhere to their hosts (Huang et al., ; Lin et al., ; Qin, Lin, Chen, Xu, & Yan, ). During infection, pathogens are able to neutralize bactericidal and bacteriostatic mechanisms to survive and replicate in various host cells, including macrophagocytes (Beaz‐Hidalgo & Figueras, ).…”

Section: Introductionmentioning

confidence: 99%

AcuC, a histone deacetylase, contributes to the pathogenicity of Aeromonas hydrophila

et al. 2017

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The interactions of pathogens and phagocytes are complex. Our study demonstrated that Aeromonas hydrophila B11 can survive in the macrophagocytes of Tilapia mossambica. To explore the regulatory processes of A. hydrophila survival in the macrophagocytes, we used the mini‐Tn10 transposon mutagenesis system to build a mutant library by mixing Escherichia coli Sm10 (pLOFKm) and A. hydrophila B11. In total, 102 mutant colonies were detected, and 11 of them showed reduced survival in macrophagocytes. The mutant with the most severe phenotype, AM73, was chosen for further research. The ORF interrupted by mini‐Tn10 in AM73 was approximately 960 bp and was deposited in GenBank with the accession number SRP049226. The 319 amino acid protein encoded by the ORF showed a high degree of identity (89%) with proteins in the histone deacetylase/AcuC/AphA family of A. hydrophila subsp. hydrophila ATCC7966. A strain (AC73) in which the acuC mutation was complemented was constructed by generating the recombinant expression plasmid pACYC184‐acuC and introducing it into the AM73 mutant strain. Our experiments revealed that strain AM73 was deficient in biofilm formation, adhesion, survival in macrophagocytes, and virulence compared with A. hydrophila B11, and all of these biological properties were improved in strain AC73. The expression of 10 significant virulence genes was significantly inhibited in strain AM73. The results indicated that AcuC was an important regulatory protein contributing to the pathogenicity of A. hydrophila.

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Flagellar motility is necessary for Aeromonas hydrophila adhesion

Cited by 54 publications

References 30 publications

Species Distribution and Prevalence of Putative Virulence Factors in Mesophilic Aeromonas spp. Isolated from Fresh Retail Sushi

Species Distribution and Prevalence of Putative Virulence Factors in Mesophilic Aeromonas spp. Isolated from Fresh Retail Sushi

Flagellar Hooks and Hook Protein FlgE Participate in Host Microbe Interactions at Immunological Level

AcuC, a histone deacetylase, contributes to the pathogenicity of Aeromonas hydrophila

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