Screening virulence factors of porcine extraintestinal pathogenic<i>Escherichia coli</i>(an emerging pathotype) required for optimal growth in swine blood

Ma, Jiale; Cheng, Zihao; Bai, Qiankun; Zhao, Kejie; Pan, Zihao; Yao, Huochun

doi:10.1111/tbed.13848

Cited by 10 publications

(16 citation statements)

References 38 publications

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“…It was further shown that Δ rfa displayed remarkable growth defects in fresh serum but not in heat-inactivated serum, indicating that lipopolysaccharides play important role in protecting ExPEC from being killed by heat-sensitive antimicrobial substances in serum, such as complements. The critical role of LPS biosynthesis in the resistance of serum killing has also been reported by other groups [ 9 , 69–71 ]. This could be attributed to the critical role of the LPS O-antigen in resistance to complement killing and hydrolysis of lysozyme [ 71 , 72 ].…”

Section: Discussionsupporting

confidence: 72%

“…ExPEC is also a common bacterial pathogen in farm animals. Apart from the well-characterized avian pathogenic E. coli (APEC) that can cause multiple local and systemic infections in poultry which is one of the leading causes of morbidity and mortality [ 8 ], ExPEC in pigs has recently emerged as a fatal pathogen causing porcine meningitis, pneumonia, and septicemia, resulting in huge economic losses [ 9–11 ]. The incidence of ExPEC in pigs is reported to be increasing in recent years [ 11–13 ].…”

Section: Introductionmentioning

confidence: 99%

“…However, the mechanisms of pathogenicity are less understood. So far, the type VI secretion system, Rhs proteins, the twin-arginine translocation system, the biosynthesis of nucleotide and extracellular polysaccharides, and the global regulators Fur and FNR have been reported critical for the virulence of porcine ExPEC [ 9 , 29–31 ]. However, the underlying mechanism of pathogenesis is far from comprehensively elaborated.…”

Section: Introductionmentioning

confidence: 99%

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Genome-wide identification of genes critical for in vivo fitness of multi-drug resistant porcine extraintestinal pathogenic Escherichia coli by transposon-directed insertion site sequencing using a mouse infection model

Yin

et al. 2023

Virulence

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Extraintestinal pathogenic Escherichia coli (ExPEC) is an important zoonotic pathogen. Recently, ExPEC has been reported to be an emerging problem in pig farming. However, the mechanism of pathogenicity of porcine ExPEC remains to be revealed. In this study, we constructed a transposon (Tn) mutagenesis library covering Tn insertion in over 72% of the chromosome-encoded genes of a virulent and multi-drug resistant porcine ExPEC strain PCN033. By using a mouse infection model, a transposon-directed insertion site sequencing (TraDIS) assay was performed to identify in vivo fitness factors. By comparing the Tn insertion frequencies between the input Tn library and the recovered library from different organs, 64 genes were identified to be involved in fitness during systemic infection. 15 genes were selected and individual gene deletion mutants were constructed. The in vivo fitness was evaluated by using a competitive infection assay. Among them, Δ fimG was significantly outcompeted by the WT strain in vivo and showed defective adhesion to host cells. rfa which was involved in lipopolysaccharide biosynthesis was shown to be critical for in vivo fitness which may have resulted from its role in the resistance to serum killing. In addition, several metabolic genes including fepB , sdhC , fepG , gltS , dcuA , ccmH , ddpD , narU , glpD , malM , and yabL and two regulatory genes metJ and baeS were shown as important determinants of in vivo fitness of porcine ExPEC. Collectively, this study performed a genome-wide screening for in vivo fitness factors which will be important for understanding the pathogenicity of porcine ExPEC.

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Section: Discussionsupporting

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Genome-wide identification of genes critical for in vivo fitness of multi-drug resistant porcine extraintestinal pathogenic Escherichia coli by transposon-directed insertion site sequencing using a mouse infection model

Yin

et al. 2023

Virulence

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“…Bacterial strains and plasmids used in this study were listed in Table S1 . PU-1 is an O2:K1 ExPEC strain (isolated from the blood of a piglet) causing acute sepsis in mouse infection model ( Ma et al., 2020 ; Ma et al., 2021 ). All strains were grown on Luria-Bertani (LB) broth medium at 37°C with 180 rpm, supplemented with corresponding antibiotics, or isopropyl–D-thiogalactopyranoside (IPTG) when necessary.…”

Section: Methodsmentioning

confidence: 99%

Porcine extraintestinal pathogenic Escherichia coli delivers two serine protease autotransporters coordinately optimizing the bloodstream infection

Pan

Chen²,

Zhang³

et al. 2023

Front. Cell. Infect. Microbiol.

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Extraintestinal pathogenic Escherichia coli (ExPEC) is one of the leading causes of bloodstream infections in a broad spectrum of birds and mammals, thus poses a great threat to public health, while its underlying mechanism causing sepsis is not fully understood. Here we reported a high virulent ExPEC strain PU-1, which has a robust ability to colonize within host bloodstream, while induced a low level of leukocytic activation. Two serine protease autotransporters of Enterobacteriaceae (SPATEs), VatPU-1 and TshPU-1, were found to play critical roles for the urgent blood infection of strain PU-1. Although the Vat and Tsh homologues have been identified as virulence factors of ExPEC, their contributions to bloodstream infection are still unclear. In this study, VatPU-1 and TshPU-1 were verified to interact with the hemoglobin (a well-known mucin-like glycoprotein in red blood cell), degrade the mucins of host respiratory tract, and cleave the CD43 (a major cell surface component sharing similar O-glycosylated modifications with other glycoprotein expressed on leukocytes), suggesting that these two SPATEs have the common activity to cleave a broad array of mucin-like O-glycoproteins. These cleavages significantly impaired the chemotaxis and transmigration of leukocytes, and then inhibited the activation of diverse immune responses coordinately, especially downregulated the leukocytic and inflammatory activation during bloodstream infection, thus might mediate the evasion of ExPEC from immune clearance of blood leukocytes. Taken together, these two SPATEs play critical roles to cause a heavy bacterial load within bloodstream via immunomodulation of leukocytes, which provides a more comprehensive understanding how ExPEC colonize within host bloodstream and cause severe sepsis.

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“…The type I pilus adhesin of ExPEC helps bacteria to colonize and invade the bladder epithelium [ 9 ]. ExPEC de novo nucleotide biosynthetic pathways allow bacteria to meet their metabolic requirements within host blood and promote bacterial growth in serum [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

Extraintestinal pathogenic Escherichia coli utilizes the surface-expressed elongation factor Tu to bind and acquire iron from holo-transferrin

Sun

Wang

et al. 2022

Virulence

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Extraintestinal pathogenic Escherichia coli (ExPEC) is a common anthropozoonotic pathogen that causes systemic infections. To establish infection, ExPEC must utilize essential nutrients including iron from the host. Transferrin is an important iron source for multiple bacteria. However, the mechanism by which ExPEC utilizes transferrin remains unclear. In this study, we found that iron-saturated holo-transferrin rather than iron-free apo-transferrin promoted the vitality of ExPEC in heat-inactivated human serum. The multifunctional protein Elongation factor Tu (EFTu) worked as a holo-transferrin binding protein. EFTu not only bound holo-transferrin rather than apo-transferrin but also released transferrin-related iron, with all domains of EFTu involved in holo-transferrin binding and iron release events. We also identified the surface location of EFTu on ExPEC. Overexpression of EFTu on the surface of nonpathogenic E. coli not only promoted the binding of bacteria to holo-transferrin but also facilitated the uptake of transferrin-related iron. More importantly, it significantly enhanced the survival of E. coli in heat-inactivated human serum, which was positively correlated with holo-transferrin but not apo-transferrin. Our research revealed a novel function of EFTu in binding holo-transferrin to promote iron uptake by bacteria, suggesting that EFTu was a potential virulence factor of ExPEC. In addition, our study provided research avenues into the iron acquisition and pathogenicity mechanisms of ExPEC.

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Screening virulence factors of porcine extraintestinal pathogenicEscherichia coli(an emerging pathotype) required for optimal growth in swine blood

Cited by 10 publications

References 38 publications

Genome-wide identification of genes critical for in vivo fitness of multi-drug resistant porcine extraintestinal pathogenic Escherichia coli by transposon-directed insertion site sequencing using a mouse infection model

Genome-wide identification of genes critical for in vivo fitness of multi-drug resistant porcine extraintestinal pathogenic Escherichia coli by transposon-directed insertion site sequencing using a mouse infection model

Porcine extraintestinal pathogenic Escherichia coli delivers two serine protease autotransporters coordinately optimizing the bloodstream infection

Extraintestinal pathogenic Escherichia coli utilizes the surface-expressed elongation factor Tu to bind and acquire iron from holo-transferrin

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