scholarly journals Characterization and Identification of a Novel Candidate Vaccine Protein through Systematic Analysis of Extracellular Proteins of Erysipelothrix rhusiopathiae

2013 ◽  
Vol 81 (12) ◽  
pp. 4333-4340 ◽  
Author(s):  
Fang Shi ◽  
Yohsuke Ogawa ◽  
Akiyuki Sano ◽  
Tomoyuki Harada ◽  
Jiro Hirota ◽  
...  
Keyword(s):  
Metabolic Enzymes ◽  
Extracellular Proteins ◽  
Vaccine Antigen ◽  
Immunogold Electron Microscopy ◽  
Major Protein ◽  
Erysipelothrix Rhusiopathiae ◽  
Lethal Challenge ◽  
Systematic Analysis ◽  
Content Type

ABSTRACTErysipelothrix rhusiopathiae, the causative agent of swine erysipelas, is a facultative intracellular Gram-positive bacterium. It has been shown that animals immunized with a filtrate fromE. rhusiopathiaecultures are protected against lethal challenge. In this study, we identified and characterized the extracellular proteins ofE. rhusiopathiaeto search for novel vaccine antigens. A concentrated culture supernatant from theE. rhusiopathiaeFujisawa strain, which has been found to induce protection in mice, was analyzed using two-dimensional electrophoresis. From more than 40 confirmed protein spots, 16 major protein spots were selected and subjected to N-terminal amino acid sequence determination, and 14 protein spots were successfully identified. The identified proteins included housekeeping proteins and other metabolic enzymes. We searched for surface-localized proteins by analyzing the genomes of twoE. rhusiopathiaestrains: Fujisawa and ATCC 19414. Genome analysis revealed that the ATCC 19414 strain has three putative surface-exposedcholine-bindingproteins (CBPs): CbpA, CbpB, and CbpC. Each CBP contains a putative choline-binding domain. The CbpC gene is mutated in Fujisawa, becoming a nonfunctional pseudogene. Immunogold electron microscopy confirmed that CbpA and CbpB, as well as the majority of the metabolic enzymes examined, are associated with the cell surface ofE. rhusiopathiaeFujisawa. Immunization with recombinant CbpB, but not with other recombinant CBPs or metabolic enzymes, protected mice against lethal challenge. A phagocytosis assay revealed that antiserum against CbpB promoted opsonin-mediated phagocytosis by murine macrophagesin vitro. The protective capabilities of CbpB were confirmed in pigs, suggesting that CbpB could be used as a vaccine antigen.

scholarly journals The Fimbrial Protein FlfA from Gallibacterium anatis Is a Virulence Factor and Vaccine Candidate

2013 ◽  
Vol 81 (6) ◽  
pp. 1964-1973 ◽  
Author(s):  
Ragnhild J. Bager ◽  
Barbara Nesta ◽  
Susanne E. Pors ◽  
Marco Soriani ◽  
Laura Serino ◽  
...  
Keyword(s):  
Egg Production ◽  
Vaccine Candidate ◽  
Gene Clusters ◽  
Egg Laying ◽  
Vaccine Antigen ◽  
Immunogold Electron Microscopy ◽  
Content Type ◽  
Subunit Protein ◽  
Fimbrial Subunit

ABSTRACTThe Gram-negative bacteriumGallibacterium anatisis a major cause of salpingitis and peritonitis in egg-laying chickens, leading to decreased egg production worldwide. Widespread multidrug resistance largely prevents treatment of this organism using traditional antimicrobial agents, while antigenic diversity hampers disease prevention by classical vaccines. Thus, insight into its pathogenesis and knowledge about important virulence factors is urgently required. A key event during the colonization and invasion of mucosal surfaces is adherence, and recently, at least three F17-like fimbrial gene clusters were identified in the genomes of severalG. anatisstrains. The objective of this study was to characterize the putative F17-like fimbrial subunit protein FlfA fromG. anatis12656-12 and determine its importance for virulence.In vitroexpression and surface exposure of FlfA was demonstrated by flow cytometry and immunofluorescence microscopy. The predicted function of FlfA as a fimbrial subunit protein was confirmed by immunogold electron microscopy. AnflfAdeletion mutant (ΔflfA) was generated inG. anatis12656-12, and importantly, this mutant was significantly attenuated in the natural chicken host. Furthermore, protection againstG. anatis12656-12 could be induced by immunizing chickens with recombinant FlfA. Finally,in vitroexpression of FlfA homologs was observed in a genetically diverse set ofG. anatisstrains, suggesting the potential of FlfA as a serotype-independent vaccine candidate This is the first study describing a fimbrial subunit protein ofG. anatiswith a clear potential as a vaccine antigen.

scholarly journals Needle-Free Delivery of Acetalated Dextran-Encapsulated AR-12 Protects Mice from Francisella tularensis Lethal Challenge

2016 ◽  
Vol 60 (4) ◽  
pp. 2052-2062 ◽  
Author(s):  
Ky V. Hoang ◽  
Heather Curry ◽  
Michael A. Collier ◽  
Hassan Borteh ◽  
Eric M. Bachelder ◽  
...  
Keyword(s):  
Francisella Tularensis ◽  
Lethal Challenge ◽  
Content Type ◽  
Human Macrophages ◽  
Gentamicin Treatment ◽  
Significant Toxicity ◽  
Serovar Typhimurium ◽  
Spectrum Activity

ABSTRACTFrancisella tularensiscauses tularemia and is a potential biothreat. Given the limited antibiotics for treating tularemia and the possible use of antibiotic-resistant strains as a biowarfare agent, new antibacterial agents are needed. AR-12 is an FDA-approved investigational new drug (IND) compound that induces autophagy and has shown host-directed, broad-spectrum activityin vitroagainstSalmonella entericaserovar Typhimurium andF. tularensis. We have shown that AR-12 encapsulated within acetalated dextran (Ace-DEX) microparticles (AR-12/MPs) significantly reduces host cell cytotoxicity compared to that with free AR-12, while retaining the ability to controlS.Typhimurium within infected human macrophages. In the present study, the toxicity and efficacy of AR-12/MPs in controlling virulent type AF. tularensisSchuS4 infection were examinedin vitroandin vivo. No significant toxicity of blank MPs or AR-12/MPs was observed in lung histology sections when the formulations were given intranasally to uninfected mice. In histology sections from the lungs of intranasally infected mice treated with the formulations, increased macrophage infiltration was observed for AR-12/MPs, with or without suboptimal gentamicin treatment, but not for blank MPs, soluble AR-12, or suboptimal gentamicin alone. AR-12/MPs dramatically reduced the burden ofF. tularensisin infected human macrophages, in a manner similar to that of free AR-12. However,in vivo, AR-12/MPs significantly enhanced the survival ofF. tularensisSchuS4-infected mice compared to that seen with free AR-12. In combination with suboptimal gentamicin treatment, AR-12/MPs further improved the survival ofF. tularensisSchuS4-infected mice. These studies provide support for Ace-DEX-encapsulated AR-12 as a promising new therapeutic agent for tularemia.

scholarly journals Immunostimulatory Effects of Recombinant Erysipelothrix rhusiopathiae Expressing Porcine Interleukin-18 in Mice and Pigs

2012 ◽  
Vol 19 (9) ◽  
pp. 1393-1398 ◽  
Author(s):  
Yohsuke Ogawa ◽  
Yu Minagawa ◽  
Fang Shi ◽  
Masahiro Eguchi ◽  
Yoshihiro Muneta ◽  
...  
Keyword(s):  
Immune Responses ◽  
Peritoneal Macrophages ◽  
Erysipelothrix Rhusiopathiae ◽  
Interleukin 18 ◽  
Murine Splenocytes ◽  
Content Type ◽  
Immunostimulatory Effect ◽  
Ifn Γ ◽  
Acquired Immune Responses

ABSTRACTInterleukin-18 (IL-18), which was originally called gamma interferon (IFN-γ)-inducing factor, has been shown to play an important role in innate and acquired immune responses. In this study, attenuatedErysipelothrix rhusiopathiaestrains were engineered to produce porcine IL-18 (poIL-18) and evaluated for their potential immunostimulatory effect in animals. Recombinant poIL-18 was successfully expressed in the recombinantE. rhusiopathiaestrains YS-1/IL-18 and KO/IL-18. The culture supernatant of YS-1/IL-18 was confirmed to induce IFN-γ production in murine splenocytesin vitro, and this production was inhibited by incubation with anti-poIL-18 monoclonal antibodies. Furthermore, more IFN-γ production was induced upon stimulation of splenocytes with concanavalin A for splenocytes from mice that were intraperitoneally inoculated with YS-1/IL-18 than for splenocytes from control mice inoculated with the parent strain YS-1. Peritoneal macrophages from mice preinoculated with YS-1/IL-18 exhibited enhanced phagocytosis ofSalmonella entericasubsp.entericaserovar Typhimurium compared with peritoneal macrophages from control mice preinoculated with YS-1. We also confirmed the immunostimulatory effect on humoral immune responses against antigens ofE. rhusiopathiaeandMycoplasma hyopneumoniaein gnotobiotic pigs that were orally preinoculated with KO/IL-18. Thus, these results provide evidence thatE. rhusiopathiaeis a promising vector for the expression of host cytokines and suggest the potential utility ofE. rhusiopathiaevector-encoded cytokines in the activation of host innate and acquired immune responses.

scholarly journals Topical Antibiotic Elution in a Collagen-Rich Hydrogel Successfully Inhibits Bacterial Growth and Biofilm Formation In Vitro

2020 ◽  
Vol 64 (10) ◽  
Author(s):  
Jung Gi Min ◽  
Uriel J. Sanchez Rangel ◽  
Austin Franklin ◽  
Hiroki Oda ◽  
Zhen Wang ◽  
...  
Keyword(s):  
Cell Death ◽  
Bacterial Growth ◽  
Biofilm Formation ◽  
Chronic Wounds ◽  
Treatment Options ◽  
Extracellular Proteins ◽  
Multiple Time ◽  
Content Type ◽  
Biofilm Disruption

ABSTRACT Chronic wounds are a prominent concern, accounting for $25 billion of health care costs annually. Biofilms have been implicated in delayed wound closure, but they are susceptible to developing antibiotic resistance and treatment options continue to be limited. A novel collagen-rich hydrogel derived from human extracellular matrix presents an avenue for treating chronic wounds by providing appropriate extracellular proteins for healing and promoting neovascularization. Using the hydrogel as a delivery system for localized secretion of a therapeutic dosage of antibiotics presents an attractive means of maximizing delivery while minimizing systemic side effects. We hypothesize that the hydrogel can provide controlled elution of antibiotics leading to inhibition of bacterial growth and disruption of biofilm formation. The rate of antibiotic elution from the collagen-rich hydrogel and the efficacy of biofilm disruption was assessed with Pseudomonas aeruginosa. Bacterial growth inhibition, biofilm disruption, and mammalian cell cytotoxicity were quantified using in vitro models. The antibiotic-loaded hydrogel showed sustained release of antibiotics for up to 24 h at therapeutic levels. The treatment inhibited bacterial growth and disrupted biofilm formation at multiple time points. The hydrogel was capable of accommodating various classes of antibiotics and did not result in cytotoxicity in mammalian fibroblasts or adipose stem cells. The antibiotic-loaded collagen-rich hydrogel is capable of controlled antibiotic release effective for bacteria cell death without native cell death. A human-derived hydrogel that is capable of eluting therapeutic levels of antibiotic is an exciting prospect in the field of chronic wound healing.

scholarly journals Capsular Polysaccharide of Erysipelothrix rhusiopathiae, the Causative Agent of Swine Erysipelas, and Its Modification with Phosphorylcholine

2012 ◽  
Vol 80 (11) ◽  
pp. 3993-4003 ◽  
Author(s):  
Fang Shi ◽  
Tomoyuki Harada ◽  
Yohsuke Ogawa ◽  
Hiroshi Ono ◽  
Mayumi Ohnishi-Kameyama ◽  
...  
Keyword(s):  
Cell Surface ◽  
Capsular Polysaccharide ◽  
Genetic Locus ◽  
Hot Water ◽  
Mycoplasma Species ◽  
Phylogenetic Position ◽  
Close Relative ◽  
Immunogold Electron Microscopy ◽  
Erysipelothrix Rhusiopathiae ◽  
Content Type

ABSTRACTThe capsule has been implicated in the virulence of the swine pathogenErysipelothrix rhusiopathiae, a rod-shaped, intracellular Gram-positive bacterium that has a unique phylogenetic position in the phylumFirmicutesand is a close relative ofMollicutes(mycoplasma species). In this study, we analyzed the genetic locus and composition of the capsular polysaccharide (CPS) of the Fujisawa strain ofE. rhusiopathiae. Genome analysis of the Fujisawa strain revealed that the genetic locus for capsular polysaccharide synthesis (cps) is located next to anlicoperon, which is involved in the incorporation and expression of phosphorylcholine (PCho). Reverse transcription-PCR analysis showed thatcpsandlicare transcribed as a single mRNA, indicating that the loci form an operon. Using the cell surface antigen-specific monoclonal antibody (MAb) ER21 as a probe, the capsular materials were isolated from the Fujisawa strain by hot water extraction and treatment with DNase, RNase, pronase, andN-acetylmuramidase SG, followed by anion-exchange and gel filtration chromatography. The materials were then analyzed by high-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance (NMR) spectroscopy. The CPS ofE. rhusiopathiaeis heterogeneous and consists of the major monosaccharides galacturonic acid, galactose, mannose, glucose, arabinose, xylose, andN-acetylglucosamine and some minor monosaccharides containing ribose, rhamnose, andN-acetylgalactosamine. In addition, the capsule is modified by PCho, which comigrates with the capsular materials, as determined by Western immunoblotting, and colocalizes on the cell surface, as determined by immunogold electron microscopy. Virulence testing of PCho-defective mutants in mice demonstrated that PCho is critical for the virulence of this organism.

scholarly journals Comparative genome analysis of Erysipelothrix rhusiopathiae isolated from domestic pigs and wild boars suggests host adaptation and selective pressure from the use of antibiotics

2020 ◽  
Vol 6 (8) ◽  
Author(s):  
Robert Söderlund ◽  
Nicoletta Formenti ◽  
Stefania Caló ◽  
Mario Chiari ◽  
Mate Zoric ◽  
...  
Keyword(s):  
Wild Boar ◽  
Host Adaptation ◽  
Extracellular Proteins ◽  
Gene Variants ◽  
Erysipelothrix Rhusiopathiae ◽  
Content Type ◽  
Wild Boars ◽  
Domestic Pigs ◽  
Resistance Determinants ◽  
Capsule Production

The disease erysipelas caused by Erysipelothrix rhusiopathiae (ER) is a major concern in pig production. In the present study the genomes of ER from pigs (n=87), wild boars (n=71) and other sources (n=85) were compared in terms of whole-genome SNP variation, accessory genome content and the presence of genetic antibiotic resistance determinants. The aim was to investigate if genetic features among ER were associated with isolate origin in order to better estimate the risk of transmission of porcine-adapted strains from wild boars to free-range pigs and to increase our understanding of the evolution of ER. Pigs and wild boars carried isolates representing all ER clades, but clade one only occurred in healthy wild boars and healthy pigs. Several accessory genes or gene variants were found to be significantly associated with the pig and wild boar hosts, with genes predicted to encode cell wall-associated or extracellular proteins overrepresented. Gene variants associated with serovar determination and capsule production in serovars known to be pathogenic for pigs were found to be significantly associated with pigs as hosts. In total, 30 % of investigated pig isolates but only 6 % of wild boar isolates carried resistance genes, most commonly tetM (tetracycline) and lsa(E) together with lnu(B) (lincosamides, pleuromutilin and streptogramin A). The incidence of variably present genes including resistance determinants was weakly linked to phylogeny, indicating that host adaptation in ER has evolved multiple times in diverse lineages mediated by recombination and the acquisition of mobile genetic elements. The presented results support the occurrence of host-adapted ER strains, but they do not indicate frequent transmission between wild boars and domestic pigs. This article contains data hosted by Microreact.

scholarly journals Memory B Cells Encode Neutralizing Antibody Specific for Toxin B from the Clostridium difficile Strains VPI 10463 and NAP1/BI/027 but with Superior Neutralization of VPI 10463 Toxin B

2015 ◽  
Vol 84 (1) ◽  
pp. 194-204 ◽  
Author(s):  
T. Scott Devera ◽  
Gillian A. Lang ◽  
Jordi M. Lanis ◽  
Pragya Rampuria ◽  
Casey L. Gilmore ◽  
...  
Keyword(s):  
B Cells ◽  
Clostridium Difficile ◽  
Mononuclear Cells ◽  
Neutralizing Antibody ◽  
Memory B Cells ◽  
Lethal Challenge ◽  
Toxin B ◽  
Content Type ◽  
Antibody Titers

Secreted toxin B (TcdB) substantially contributes to the pathology observed duringClostridium difficileinfection. To be successfully incorporated into a vaccine, TcdB-based immunogens must stimulate the production of neutralizing antibody (Ab)-encoding memory B cells (Bmem cells). Despite numerous investigations, a clear analysis of Bmem cellular responses following vaccination against TcdB is lacking. B6 mice were therefore used to test the ability of a nontoxigenic C-terminal domain (CTD) fragment of TcdB to induce Bmem cells that encode TcdB-neutralizing antibody. CTD was produced from the historical VPI 10463 strain (CTD1) and from the hypervirulent strain NAP1/BI/027 (CTD2). It was then demonstrated that CTD1 induced strong recall IgG antibody titers, and this led to the development of functional Bmem cells that could be adoptively transferred to naive recipients. Bmem cell-driven neutralizing Ab responses conferred protection against lethal challenge with TcdB1. Further experiments revealed that an experimental adjuvant (Imject) and a clinical adjuvant (Alhydrogel) were compatible with Bmem cell induction. Reactivity of human Bmem cells to CTD1 was also evident in human peripheral blood mononuclear cells (PBMCs), suggesting that CTD1 could be a good vaccine immunogen. However, CTD2 induced strong Bmem cell-driven antibody titers, and the CTD2 antibody was neutralizingin vitro, but its protection against lethal challenge with TcdB2 was limited to delaying time to death. Therefore, CTD from differentC. difficilestrains may be a good immunogen for stimulating B cell memory that encodesin vitroneutralizing Ab but may be limited by variable protection against intoxicationin vivo.

scholarly journals Antibodies against the Majority Subunit (PilA) of the Type IV Pilus of NontypeableHaemophilus influenzaeDisperseMoraxella catarrhalisfrom a Dual-Species Biofilm

mBio ◽  
2018 ◽  
Vol 9 (6) ◽  
Author(s):  
Elaine M. Mokrzan ◽  
Laura A. Novotny ◽  
Kenneth L. Brockman ◽  
Lauren O. Bakaletz
Keyword(s):  
Otitis Media ◽  
Middle Ear ◽  
Vaccine Development ◽  
Therapeutic Vaccine ◽  
Vaccine Antigen ◽  
Soluble Form ◽  
Great Promise ◽  
Content Type ◽  
Type Iv

ABSTRACTOtitis media (OM) is often polymicrobial, with nontypeableHaemophilus influenzae(NTHI) andMoraxella catarrhalis(Mcat) frequently cocultured from clinical specimens. Bacterial biofilms in the middle ear contribute to the chronicity and recurrence of OM; therefore, strategies to disrupt biofilms are needed. We have focused our vaccine development efforts on the majority subunit of NTHI type IV pili, PilA. Antibodies against a recombinant, soluble form of PilA (rsPilA) both disrupt and prevent the formation of NTHI biofilmsin vitro.Moreover, immunization with rsPilA prevents and resolves NTHI-induced experimental OM. Here, we show that antibodies against rsPilA also prevent and disrupt polymicrobial biofilms. Dual-species biofilms formed by NTHI and Mcat at temperatures that mimic the human nasopharynx (34°C) or middle ear (37°C) were exposed to antiserum against either rsPilA or the OMP P5 adhesin of NTHI. NTHI+Mcat biofilm formation was significantly inhibited by antiserum directed against both adhesin proteins at either temperature. However, only anti-rsPilA disrupted NTHI+Mcat preestablished biofilms at either temperature and actively dispersed both NTHI and Mcat via interspecies quorum signaling. Newly released NTHI and Mcat were significantly more susceptible to killing by antibiotics. Taken together, these results revealed new opportunities for treatment of biofilm-associated diseases via a strategy that combines vaccine-induced antibody-mediated biofilm dispersal with traditional antibiotics, at a significantly reduced dosage to exploit the newly released, antibiotic-sensitive phenotype. Combined, our data strongly support the utility of rsPilA both as a preventative and as a therapeutic vaccine antigen for polymicrobial OM due to NTHI and Mcat.IMPORTANCEMiddle ear infections (or otitis media [OM]) are highly prevalent among children worldwide and present a tremendous socioeconomic challenge for health care systems. More importantly, this disease diminishes the quality of life of young children. OM is often chronic and recurrent, due to the presence of highly antibiotic-resistant communities of bacteria (called biofilms) that persist within the middle ear space. To combat these recalcitrant infections, new and powerful biofilm-directed approaches are needed. Here, we describe the ability to disrupt a biofilm formed by the two most common bacteria that cause chronic and recurrent OM in children, via an approach that combines the power of vaccines with that of traditional antibiotics. An outcome of this strategy is that antibiotics can more easily kill the bacteria that our vaccine-induced antibodies have released from the biofilm. We believe that this approach holds great promise for both the prevention and treatment of OM.

scholarly journals LtpD Is a Novel Legionella pneumophila Effector That Binds Phosphatidylinositol 3-Phosphate and Inositol Monophosphatase IMPA1

2013 ◽  
Vol 81 (11) ◽  
pp. 4261-4270 ◽  
Author(s):  
Clare R. Harding ◽  
Corinna Mattheis ◽  
Aurélie Mousnier ◽  
Clare V. Oates ◽  
Elizabeth L. Hartland ◽  
...  
Keyword(s):  
Host Cell ◽  
Legionella Pneumophila ◽  
Galleria Mellonella ◽  
Effector Proteins ◽  
Lung Epithelial Cells ◽  
Systematic Analysis ◽  
Content Type ◽  
Bacterial Replication ◽  
Phosphatidylinositol 3

ABSTRACTThe Dot/Icm type IV secretion system (T4SS) ofLegionella pneumophilais crucial for the pathogen to survive in protozoa and cause human disease. Although more than 275 effector proteins are delivered into the host cell by the T4SS, the function of the majority is unknown. Here we have characterized the Dot/Icm effector LtpD. During infection, LtpD localized to the cytoplasmic face of the membrane of theLegionella-containing vacuole (LCV). In A549 lung epithelial cells, ectopically expressed LtpD localized to large vesicular structures that contained markers of endosomal compartments. Systematic analysis of LtpD fragments identified an internal 17-kDa fragment, LtpD471-626, which was essential for targeting ectopically expressed LtpD to vesicular structures and for the association of translocated LtpD with the LCV. LtpD471-626bound directly to phosphatidylinositol 3-phosphate [PtdIns(3)P]in vitroand colocalized with the PtdIns(3)P markers FYVE and SetA in cotransfected cells. LtpD was also found to bind the host cell enzyme inositol (myo)-1 (or 4)-monophosphatase 1, an important phosphatase involved in phosphoinositide production. Analysis of the role of LtpD in infection showed that LtpD is involved in bacterial replication in THP-1 macrophages, the larvae ofGalleria mellonella, and mouse lungs. Together, these data suggest that LtpD is a novel phosphoinositide-bindingL. pneumophilaeffector that has a role in intracellular bacterial replication.

scholarly journals Characterization and Functional Analysis of AatB, a Novel Autotransporter Adhesin and Virulence Factor of Avian Pathogenic Escherichia coli

2013 ◽  
Vol 81 (7) ◽  
pp. 2437-2447 ◽  
Author(s):  
Xiangkai ZhuGe ◽  
Shaohui Wang ◽  
Hongjie Fan ◽  
Zihao Pan ◽  
Jianluan Ren ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
Large Family ◽  
Extracellular Proteins ◽  
Dimensional Structure ◽  
Phylogenetic Groups ◽  
Passenger Domain ◽  
Content Type

ABSTRACTAutotransporter (AT) proteins constitute a large family of extracellular proteins that contribute to bacterial virulence. A novel AT adhesin gene,aatB, was identified in avian pathogenicEscherichia coli(APEC) DE205B via genomic analyses. The open reading frame ofaatBwas 1,017 bp, encoding a putative 36.3-kDa protein which contained structural motifs characteristic for AT proteins: a signal peptide, a passenger domain, and a translocator domain. The predicted three-dimensional structure of AatB consisted of two distinct domains, the C-terminal β-barrel translocator domain and an N-terminal passenger domain. The prevalence analyses ofaatBin APEC indicated thataatBwas detected in 26.4% (72/273) of APEC strains and was strongly associated with phylogenetic groups D and B2. Quantitative real-time reverse transcription-PCR analyses revealed that AatB expression was increased during infectionin vitroandin vivo. Moreover, AatB could elicit antibodies in infected ducks, suggesting that AatB is involved in APEC pathogenicity. Thus, APEC DE205B strains with a mutatedaatBgene and mutated strains complemented with theaatBgene were constructed. Inactivation ofaatBresulted in a reduced capacity to adhere to DF-1 cells, defective virulence capacityin vivo, and decreased colonization capacity in lung during systemic infection compared with the capacities of the wild-type strain. Furthermore, these capacities were restored in the complementation strains. These results indicated that AatB makes a significant contribution to APEC virulence through bacterial adherence to host tissuesin vivoandin vitro. In addition, biofilm formation assays with strain AAEC189 expressing AatB indicated that AatB mediates biofilm formation.

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