scholarly journals Toxin B Variants from Clostridium difficile Strains VPI 10463 and NAP1/027 Share Similar Substrate Profile and Cellular Intoxication Kinetics but Use Different Host Cell Entry Factors

Toxins ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 348 ◽  
Author(s):  
Diana López-Ureña ◽  
Josué Orozco-Aguilar ◽  
Yendry Chaves-Madrigal ◽  
Andrea Ramírez-Mata ◽  
Amanda Villalobos-Jimenez ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
Small Gtpases ◽  
Cell Entry ◽  
Intestinal Loop ◽  
Loop Model ◽  
Toxin B ◽  
Binding Domains ◽  
Crucial Difference ◽  
Sequence Variations

Clostridium difficile induces antibiotic-associated diarrhea due to the release of toxin A (TcdA) and toxin B (TcdB), the latter being its main virulence factor. The epidemic strain NAP1/027 has an increased virulence attributed to different factors. We compared cellular intoxication by TcdBNAP1 with that by the reference strain VPI 10463 (TcdBVPI). In a mouse ligated intestinal loop model, TcdBNAP1 induced higher neutrophil recruitment, cytokine release, and epithelial damage than TcdBVPI. Both toxins modified the same panel of small GTPases and exhibited similar in vitro autoprocessing kinetics. On the basis of sequence variations in the frizzled-binding domain (FBD), we reasoned that TcdBVPI and TcdBNAP1 might have different receptor specificities. To test this possibility, we used a TcdB from a NAP1 variant strain (TcdBNAP1v) unable to glucosylate RhoA but with the same receptor-binding domains as TcdBNAP1. Cells were preincubated with TcdBNAP1v to block cellular receptors, prior to intoxication with either TcdBVPI or TcdBNAP1. Preincubation with TcdBNAP1v blocked RhoA glucosylation by TcdBNAP1 but not by TcdBVPI, indicating that the toxins use different host factors for cell entry. This crucial difference might explain the increased biological activity of TcdBNAP1 in the intestine, representing a contributing factor for the increased virulence of the NAP1/027 strain.

scholarly journals Molecular Analysis of the gyrA and gyrB Quinolone Resistance-Determining Regions of Fluoroquinolone-Resistant Clostridium difficile Mutants Selected In Vitro

2009 ◽  
Vol 53 (6) ◽  
pp. 2463-2468 ◽  
Author(s):  
Patrizia Spigaglia ◽  
Fabrizio Barbanti ◽  
Thomas Louie ◽  
Frédéric Barbut ◽  
Paola Mastrantonio
Keyword(s):  
Clostridium Difficile ◽  
Clinical Isolates ◽  
Fluoroquinolone Resistance ◽  
Toxin B ◽  
Relevant Role ◽  
Vitro Development ◽  
Selection Of

ABSTRACT Recent studies have suggested that exposure to fluoroquinolones represents a risk factor for the development of Clostridium difficile infections and that the acquisition of resistance to the newer fluoroquinolones is the major reason facilitating wide dissemination. In particular, moxifloxacin (MX) and levofloxacin (LE) have been recently associated with outbreaks caused by the C. difficile toxinotype III/PCR ribotype 027/pulsed-field gel electrophoresis type NAP1 strain. In this study, we evaluated the potential of MX and LE in the in vitro development of fluoroquinolone resistance mediated by GyrA and GyrB alterations. Resistant mutants were obtained from five C. difficile parent strains, susceptible to MX, LE, and gatifloxacin (GA) and belonging to different toxinotypes, by selection in the presence of increasing concentrations of MX and LE. Stable mutants showing substitutions in GyrA and/or GyrB were obtained from the parent strains after selection by both antibiotics. Mutants had MICs ranging from 8 to 128 μg/ml for MX, from 8 to 256 μg/ml for LE, and from 1.5 to ≥32 μg/ml for GA. The frequency of mutation ranged from 3.8 × 10−6 to 6.6 × 10−5 for MX and from 1.0 × 10−6 to 2.4 × 10−5 for LE. In total, six different substitutions in GyrA and five in GyrB were observed in this study. The majority of these substitutions has already been described for clinical isolates or has occurred at positions known to be involved in fluoroquinolone resistance. In particular, the substitution Thr82 to Ile in GyrA, the most common found in resistant C. difficile clinical isolates, was observed after selection with LE, whereas the substitution Asp426 to Val in GyrB, recently described in toxin A-negative/toxin B-positive epidemic strains, was observed after selection with MX. Interestingly, a reduced susceptibility to fluoroquinolones was observed in colonies isolated after the first and second steps of selection by both MX and LE, with no substitution in GyrA or GyrB. The results suggest a relevant role of fluoroquinolones in the emergence and selection of fluoroquinolone-resistant C. difficile strains also in vivo.

scholarly journals A Replicating Single-Cycle Adenovirus Vaccine Effective against Clostridium difficile

Vaccines ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 470
Author(s):  
William E. Matchett ◽  
Stephanie Anguiano-Zarate ◽  
Goda Baddage Rakitha Malewana ◽  
Haley Mudrick ◽  
Melissa Weldy ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
Neutralizing Antibodies ◽  
Antibody Responses ◽  
Complete Protection ◽  
Single Cycle ◽  
Toxin B ◽  
Toxin Binding ◽  
Binding Domains ◽  
Binding Antibody

Clostridium difficile causes nearly 500,000 infections and nearly 30,000 deaths each year in the U.S., which is estimated to cost $4.8 billion. C. difficile infection (CDI) arises from bacteria colonizing the large intestine and releasing two toxins, toxin A (TcdA) and toxin B (TcdB). Generating humoral immunity against C. difficile’s toxins provides protection against primary infection and recurrence. Thus, a vaccine may offer the best opportunity for sustained, long-term protection. We developed a novel single-cycle adenovirus (SC-Ad) vaccine against C. difficile expressing the receptor-binding domains from TcdA and TcdB. The single immunization of mice generated sustained toxin-binding antibody responses and protected them from lethal toxin challenge for up to 38 weeks. Immunized Syrian hamsters produced significant toxin-neutralizing antibodies that increased over 36 weeks. Single intramuscular immunization provided complete protection against lethal BI/NAP1/027 spore challenge 45 weeks later. These data suggest that this replicating vaccine may prove useful against CDI in humans.

scholarly journals Mutational Analysis of the Enzymatic Domain of Clostridium difficile Toxin B Reveals Novel Inhibitors of the Wild-Type Toxin

2003 ◽  
Vol 71 (6) ◽  
pp. 3294-3301 ◽  
Author(s):  
Lea M. Spyres ◽  
Jeremy Daniel ◽  
Amy Hensley ◽  
Maen Qa'Dan ◽  
William Ortiz-Leduc ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
Enzymatic Activity ◽  
Protective Antigen ◽  
Mutational Analysis ◽  
Lethal Factor ◽  
Cell Entry ◽  
Heterologous Proteins ◽  
Toxin B ◽  
Intracellular Location ◽  
Clostridium Difficile Toxin B

ABSTRACT Toxin B (TcdB), a major Clostridium difficile virulence factor, glucosylates and inactivates the small GTP-binding proteins Rho, Rac, and Cdc42. In the present study we provide evidence that enzymatically inactive fragments of the TcdB enzymatic domain are effective intracellular inhibitors of native TcdB. Site-directed and deletion mutants of the TcdB enzymatic region (residues 1 to 556), lacking receptor binding and cell entry domains, were analyzed for attenuation of glucosyltransferase and glucosylhydrolase activity. Five of six derivatives from TcdB1-556 were found to be devoid of enzymatic activity. In order to facilitate cell entry, mutants were genetically fused to lfn, which encodes the protective antigen binding region of anthrax toxin lethal factor and mediates the cell entry of heterologous proteins. In line with reduced enzymatic activity, the mutants also lacked cytotoxicity. Remarkably, pretreatment or cotreatment of cells with four of the mutants provided protection against the cytotoxic effects of native TcdB. Furthermore, a CHO cell line expressing enzymatically active TcdB1-556 was also protected by the mutant-derived inhibitors, suggesting that inhibition occurred at an intracellular location. Protection also was afforded by the inhibitor to cells treated with Clostridium sordellii lethal toxin (TcsL), which uses the same cosubstrate as TcdB but shares Rac only as a common substrate target. Finally, the inhibitor did not provide protection against Clostridium novyi alpha-toxin (Τcnα), which shares similar substrates with TcdB yet uses a different cosubstrate. This is the first report to demonstrate that the potential exists to inhibit toxins at their intracellular site of action by using inactive mutants.

scholarly journals Human Monoclonal Antibodies Directed against Toxins A and B Prevent Clostridium difficile-Induced Mortality in Hamsters

2006 ◽  
Vol 74 (11) ◽  
pp. 6339-6347 ◽  
Author(s):  
Gregory J. Babcock ◽  
Teresa J. Broering ◽  
Hector J. Hernandez ◽  
Robert B. Mandell ◽  
Katherine Donahue ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Clostridium Difficile ◽  
Human Monoclonal Antibodies ◽  
Toxin A ◽  
Hamster Model ◽  
Cytotoxic Effects ◽  
Toxin B ◽  
Reduction Of Mortality

ABSTRACT Clostridium difficile is the leading cause of nosocomial antibiotic-associated diarrhea, and recent outbreaks of strains with increased virulence underscore the importance of identifying novel approaches to treat and prevent relapse of Clostridium difficile-associated diarrhea (CDAD). CDAD pathology is induced by two exotoxins, toxin A and toxin B, which have been shown to be cytotoxic and, in the case of toxin A, enterotoxic. In this report we describe fully human monoclonal antibodies (HuMAbs) that neutralize these toxins and prevent disease in hamsters. Transgenic mice carrying human immunoglobulin genes were used to isolate HuMAbs that neutralize the cytotoxic effects of either toxin A or toxin B in cell-based in vitro neutralization assays. Three anti-toxin A HuMAbs (3H2, CDA1, and 1B11) could all inhibit the enterotoxicity of toxin A in mouse intestinal loops and the in vivo toxicity in a systemic mouse model. Four anti-toxin B HuMAbs (MDX-1388, 103-174, 1G10, and 2A11) could neutralize cytotoxicity in vitro, although systemic toxicity in the mouse could not be neutralized. Anti-toxin A HuMAb CDA1 and anti-toxin B HuMAb MDX-1388 were tested in the well-established hamster model of C. difficile disease. CDA1 alone resulted in a statistically significant reduction of mortality in hamsters; however, the combination treatment offered enhanced protection. Compared to controls, combination therapy reduced mortality from 100% to 45% (P < 0.0001) in the primary disease hamster model and from 78% to 32% (P < 0.0001) in the less stringent relapse model.

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 Saccharomyces boulardii Protease Inhibits the Effects of Clostridium difficile Toxins A and B in Human Colonic Mucosa

1999 ◽  
Vol 67 (1) ◽  
pp. 302-307 ◽  
Author(s):  
Ignazio Castagliuolo ◽  
Martin F. Riegler ◽  
Leyla Valenick ◽  
J. Thomas LaMont ◽  
Charalabos Pothoulakis
Keyword(s):  
Clostridium Difficile ◽  
Colonic Mucosa ◽  
Rabbit Antiserum ◽  
Saccharomyces Boulardii ◽  
Protective Effects ◽  
Toxin A ◽  
Mucosal Permeability ◽  
Toxin B ◽  
Ussing Chambers

ABSTRACT Saccharomyces boulardii is a nonpathogenic yeast used in the treatment of Clostridium difficile diarrhea and colitis. We have reported that S. boulardii inhibitsC. difficile toxin A enteritis in rats by releasing a 54-kDa protease which digests the toxin A molecule and its brush border membrane (BBM) receptor (I. Castagliuolo, J. T. LaMont, S. T. Nikulasson, and C. Pothoulakis, Infect. Immun. 64:5225–5232, 1996). The aim of this study was to further evaluate the role of S. boulardii protease in preventing C. difficile toxin A enteritis in rat ileum and determine whether it protects human colonic mucosa from C. difficile toxins. A polyclonal rabbit antiserum raised against purified S. boulardii serine protease inhibited by 73% the proteolytic activity present in S. boulardii conditioned medium in vitro. The anti-protease immunoglobulin G (IgG) prevented the action of S. boulardiion toxin A-induced intestinal secretion and mucosal permeability to [3H]mannitol in rat ileal loops, while control rabbit IgG had no effect. The anti-protease IgG also prevented the effects ofS. boulardii protease on digestion of toxins A and B and on binding of [3H]toxin A and [3H]toxin B to purified human colonic BBM. Purified S. boulardii protease reversed toxin A- and toxin B-induced inhibition of protein synthesis in human colonic (HT-29) cells. Furthermore, toxin A- and B-induced drops in transepithelial resistance in human colonic mucosa mounted in Ussing chambers were reversed by 60 and 68%, respectively, by preexposing the toxins to S. boulardii protease. We conclude that the protective effects of S. boulardii onC. difficile-induced inflammatory diarrhea in humans are due, at least in part, to proteolytic digestion of toxin A and B molecules by a secreted protease.

Surface blebbing and cytoskeletal changes induced in vitro by toxin B from Clostridium difficile: An immunochemical and ultrastructural study

1990 ◽  
Vol 52 (3) ◽  
pp. 340-356 ◽  
Author(s):  
W. Malorni ◽  
C. Fiorentini ◽  
S. Paradisi ◽  
M. Giuliano ◽  
P. Mastrantonio ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
Ultrastructural Study ◽  
Toxin B

scholarly journals Potential Therapeutic Effects of Mepacrine againstClostridium perfringensEnterotoxin in a Mouse Model of Enterotoxemia

2019 ◽  
Vol 87 (4) ◽  
Author(s):  
Mauricio A. Navarro ◽  
Archana Shrestha ◽  
John C. Freedman ◽  
Juliann Beingesser ◽  
Bruce A. McClane ◽  
...  
Keyword(s):  
Pore Formation ◽  
Food Poisoning ◽  
Gastrointestinal Diseases ◽  
Intestinal Loop ◽  
Therapeutic Effects ◽  
Intestinal Damage ◽  
Loop Model ◽  
Content Type

ABSTRACTClostridium perfringensenterotoxin (CPE) is a pore-forming toxin that causes the symptoms of common bacterial food poisoning and several non-foodborne human gastrointestinal diseases, including antibiotic-associated diarrhea and sporadic diarrhea. In some cases, CPE-mediated disease can be very severe or fatal due to the involvement of enterotoxemia. Therefore, the development of potential therapeutics against CPE action during enterotoxemia is warranted. Mepacrine, an acridine derivative drug with broad-spectrum effects on pores and channels in mammalian membranes, has been used to treat protozoal intestinal infections in human patients. A previous study showed that the presence of mepacrine inhibits CPE-induced pore formation and activity in enterocyte-like Caco-2 cells, reducing the cytotoxicity caused by this toxinin vitro. Whether mepacrine is similarly protective against CPE actionin vivohas not been tested. When the current study evaluated whether mepacrine protects against CPE-induced death and intestinal damage using a murine ligated intestinal loop model, mepacrine protected mice from the enterotoxemic lethality caused by CPE. This protection was accompanied by a reduction in the severity of intestinal lesions induced by the toxin. Mepacrine did not reduce CPE pore formation in the intestine but inhibited absorption of the toxin into the blood of some mice. Protection from enterotoxemic death correlated with the ability of this drug to reduce CPE-induced hyperpotassemia. Thesein vivofindings, coupled with previousin vitrostudies, support mepacrine as a potential therapeutic against CPE-mediated enterotoxemic disease.

scholarly journals A Combination of Three Fully Human Toxin A- and Toxin B-Specific Monoclonal Antibodies Protects against Challenge with Highly Virulent Epidemic Strains of Clostridium difficile in the Hamster Model

2015 ◽  
Vol 22 (7) ◽  
pp. 711-725 ◽  
Author(s):  
Natalie G. Anosova ◽  
Leah E. Cole ◽  
Lu Li ◽  
Jinrong Zhang ◽  
Anna M. Brown ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Clostridium Difficile ◽  
Toxin A ◽  
Healthy Human ◽  
Hamster Model ◽  
Toxin B ◽  
Content Type ◽  
Highly Virulent

ABSTRACTClostridium difficileinfection (CDI) is the principal cause of nosocomial diarrhea and pseudomembranous colitis associated with antibiotic therapy. Recent increases in the number of outbreaks attributed to highly virulent antibiotic-resistant strains underscore the importance of identifying efficacious alternatives to antibiotics to control this infection. CDI is mediated by two large exotoxins, toxins A and B. Strong humoral toxin-specific immune responses are associated with recovery and a lack of disease recurrence, whereas insufficient humoral responses are associated with recurrent CDI. Multiple approaches targeting these toxins, including intravenous immunoglobulin, neutralizing polymers, active vaccines, and, most recently, monoclonal antibodies (MAbs), have been explored, with various degrees of success. In this study, we describe the characterization of the first MAbs isolated from healthy human donors using a high-throughput B-cell cloning strategy. The MAbs were selected based on their ability to inhibit the actions of toxins A and Bin vitroand because of theirin vivoefficacy in a hamster challenge model. A potent 2-MAb cocktail was identified and then further potentiated by the addition of a second anti-toxin B MAb. This 3-MAb combination protected animals against mortality and also reduced the severity and duration of diarrhea associated with challenge with highly virulent strains ofC. difficiletoxinotypes 0 and III. This highly efficacious cocktail consists of one MAb specific to the receptor binding domain of toxin A and two MAbs specific to nonoverlapping regions of the glucosyltransferase domain of toxin B. This MAb combination offers great potential as a nonantibiotic treatment for the prevention of recurrent CDI.

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