inactivated toxin b (toxoided tcdb)  (TechLab Inc)

Journal: FEMS Microbiology Reviews

Article Title: The role of toxins in Clostridium difficile infection

doi: 10.1093/femsre/fux048

Figure Lengend Snippet: Sequence comparisons of the large glucosylating toxins.

Article Snippet: These include a toxoid-based vaccine containing formalin-inactivated TcdA and TcdB from VPI10463 (called Cdiffense) developed by Sanofi Pasteur (Phase III clinical trial identifier: {"type":"clinical-trial","attrs":{"text":"NCT01887912","term_id":"NCT01887912"}} NCT01887912 ), a genetically modified and formalin-inactivated toxoid vaccine developed by Pfizer (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02117570","term_id":"NCT02117570"}} NCT02117570 and {"type":"clinical-trial","attrs":{"text":"NCT02561195","term_id":"NCT02561195"}} NCT02561195 ), and a recombinant fusion protein of TcdA and TcdB C-terminal domains (VLA84 or IC84) developed by Valneva Austria GmbH (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02316470","term_id":"NCT02316470"}} NCT02316470 ) (Martin and Wilcox 2016 ; Feher, Soriano and Mensa 2017 ).

Techniques: Sequencing

Journal: FEMS Microbiology Reviews

Article Title: The role of toxins in Clostridium difficile infection

doi: 10.1093/femsre/fux048

Figure Lengend Snippet: Organization of toxin genes. (A) Schematic representation of the pathogenicity locus (PaLoc). Toxin-encoding genes, tcdA and tcdB, are indicated by blue arrows; regulatory genes are shown in light green (tcdR; positive) or red (tcdC; negative); and holin-encoding gene tcdE is shown in dark green. The direction of the arrows reflects the direction of transcription. TcdR positively regulates its own expression as well as the expression of tcdA and tcdB (indicated by brown arrows). TcdC is an anti-sigma factor that negatively regulates toxin expression by interfering with TcdR function. TcdE is involved in the secretion of toxins. (B) Schematic representation of the binary toxin locus (CdtLoc). CDT-encoding genes, cdtA and cdtB, are shown in blue. The regulatory gene cdtR is shown in light green. CdtR positively regulates the transcription of cdtA and cdtB.

Article Snippet: These include a toxoid-based vaccine containing formalin-inactivated TcdA and TcdB from VPI10463 (called Cdiffense) developed by Sanofi Pasteur (Phase III clinical trial identifier: {"type":"clinical-trial","attrs":{"text":"NCT01887912","term_id":"NCT01887912"}} NCT01887912 ), a genetically modified and formalin-inactivated toxoid vaccine developed by Pfizer (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02117570","term_id":"NCT02117570"}} NCT02117570 and {"type":"clinical-trial","attrs":{"text":"NCT02561195","term_id":"NCT02561195"}} NCT02561195 ), and a recombinant fusion protein of TcdA and TcdB C-terminal domains (VLA84 or IC84) developed by Valneva Austria GmbH (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02316470","term_id":"NCT02316470"}} NCT02316470 ) (Martin and Wilcox 2016 ; Feher, Soriano and Mensa 2017 ).

Techniques: Expressing

Journal: FEMS Microbiology Reviews

Article Title: The role of toxins in Clostridium difficile infection

doi: 10.1093/femsre/fux048

Figure Lengend Snippet: TcdA and TcdB primary structure and mechanism of action. (A) TcdA and TcdB are organized into four functional domains: the glycosyltransferase domain (GTD; pink), the autoprocessing domain (APD; green), the delivery or pore-forming domain (blue) and the combined repetitive oligopeptides domain (CROPS; yellow). (B) The four functional domains contribute to a multistep mechanism of intoxication. TcdA and TcdB bind different cell surface proteins or sugars on the colonic epithelium (step 1) and are internalized by distinct endocytic pathways (step 2). The toxins reach acidified endosomes (step 3) and the low pH triggers a conformational change in the toxin delivery domain, resulting in pore formation and translocation of the GTD (and likely the APD) into the cytosol (step 4). Inositol hexakisphosphate (InsP6) binds and activates the APD, resulting in the cleavage and release of the GTD (step 5). The GTD inactivates Rho family proteins by transferring the glucose moiety (orange squares) from UDP-glucose to the switch I region of the GTPase (step 6). Glucosylation disrupts GTPase signaling and leads to cytopathic ‘rounding’ effects and apoptotic cell death.

Article Snippet: These include a toxoid-based vaccine containing formalin-inactivated TcdA and TcdB from VPI10463 (called Cdiffense) developed by Sanofi Pasteur (Phase III clinical trial identifier: {"type":"clinical-trial","attrs":{"text":"NCT01887912","term_id":"NCT01887912"}} NCT01887912 ), a genetically modified and formalin-inactivated toxoid vaccine developed by Pfizer (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02117570","term_id":"NCT02117570"}} NCT02117570 and {"type":"clinical-trial","attrs":{"text":"NCT02561195","term_id":"NCT02561195"}} NCT02561195 ), and a recombinant fusion protein of TcdA and TcdB C-terminal domains (VLA84 or IC84) developed by Valneva Austria GmbH (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02316470","term_id":"NCT02316470"}} NCT02316470 ) (Martin and Wilcox 2016 ; Feher, Soriano and Mensa 2017 ).

Techniques: Functional Assay, Translocation Assay, Transferring

Journal: FEMS Microbiology Reviews

Article Title: The role of toxins in Clostridium difficile infection

doi: 10.1093/femsre/fux048

Figure Lengend Snippet: Structure of the CROPS domain. (A) The CROPS domains of TcdA and TcdB consist of a series of short repeat (SR, yellow) sequences with interspersed long repeat (LR, purple) sequences. (B) A model of the full TcdA CROPS based on a fragment structure (2F6E) is corroborated by (C) negative stain electron microscopy images of TcdA (left) and TcdB (right). (D) The crystal structure of a CROPS fragment from the TcdA C-terminus (2G7C) shows how trisaccharides (orange carbons) bind at the vertices created at the intersection of an SR and LR.

Article Snippet: These include a toxoid-based vaccine containing formalin-inactivated TcdA and TcdB from VPI10463 (called Cdiffense) developed by Sanofi Pasteur (Phase III clinical trial identifier: {"type":"clinical-trial","attrs":{"text":"NCT01887912","term_id":"NCT01887912"}} NCT01887912 ), a genetically modified and formalin-inactivated toxoid vaccine developed by Pfizer (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02117570","term_id":"NCT02117570"}} NCT02117570 and {"type":"clinical-trial","attrs":{"text":"NCT02561195","term_id":"NCT02561195"}} NCT02561195 ), and a recombinant fusion protein of TcdA and TcdB C-terminal domains (VLA84 or IC84) developed by Valneva Austria GmbH (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02316470","term_id":"NCT02316470"}} NCT02316470 ) (Martin and Wilcox 2016 ; Feher, Soriano and Mensa 2017 ).

Techniques: Staining, Electron Microscopy

Journal: FEMS Microbiology Reviews

Article Title: The role of toxins in Clostridium difficile infection

doi: 10.1093/femsre/fux048

Figure Lengend Snippet: The autoprocessing domain (APD) undergoes a significant conformational change upon binding to InsP6. The crystal structures of the TcdA APD in the (A) absence (4R04) and (B) presence of InsP6 (3HO6) reveal significant changes in the central β-flap structure (blue) and the C-terminal sequence that follows (teal). The structure of the APD in the context of TcdA4-1802 revealed the unexpected requirement for zinc (orange sphere) in TcdA and TcdB autoprocessing activity. Other key residues include Asp 589, His 655 and Cys 700 (side chains depicted with orange carbon atoms). His 759 is located at the tip of the β-flap and is bound to the zinc in the absence of InsP6. It moves significantly upon InsP6 binding.

Article Snippet: These include a toxoid-based vaccine containing formalin-inactivated TcdA and TcdB from VPI10463 (called Cdiffense) developed by Sanofi Pasteur (Phase III clinical trial identifier: {"type":"clinical-trial","attrs":{"text":"NCT01887912","term_id":"NCT01887912"}} NCT01887912 ), a genetically modified and formalin-inactivated toxoid vaccine developed by Pfizer (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02117570","term_id":"NCT02117570"}} NCT02117570 and {"type":"clinical-trial","attrs":{"text":"NCT02561195","term_id":"NCT02561195"}} NCT02561195 ), and a recombinant fusion protein of TcdA and TcdB C-terminal domains (VLA84 or IC84) developed by Valneva Austria GmbH (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02316470","term_id":"NCT02316470"}} NCT02316470 ) (Martin and Wilcox 2016 ; Feher, Soriano and Mensa 2017 ).

Techniques: Binding Assay, Sequencing, Activity Assay

Journal: FEMS Microbiology Reviews

Article Title: The role of toxins in Clostridium difficile infection

doi: 10.1093/femsre/fux048

Figure Lengend Snippet: Substrate specificity of the large glucosylating toxins.

Article Snippet: These include a toxoid-based vaccine containing formalin-inactivated TcdA and TcdB from VPI10463 (called Cdiffense) developed by Sanofi Pasteur (Phase III clinical trial identifier: {"type":"clinical-trial","attrs":{"text":"NCT01887912","term_id":"NCT01887912"}} NCT01887912 ), a genetically modified and formalin-inactivated toxoid vaccine developed by Pfizer (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02117570","term_id":"NCT02117570"}} NCT02117570 and {"type":"clinical-trial","attrs":{"text":"NCT02561195","term_id":"NCT02561195"}} NCT02561195 ), and a recombinant fusion protein of TcdA and TcdB C-terminal domains (VLA84 or IC84) developed by Valneva Austria GmbH (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02316470","term_id":"NCT02316470"}} NCT02316470 ) (Martin and Wilcox 2016 ; Feher, Soriano and Mensa 2017 ).

Techniques:

Journal: FEMS Microbiology Reviews

Article Title: The role of toxins in Clostridium difficile infection

doi: 10.1093/femsre/fux048

Figure Lengend Snippet: Cellular effects of C. difficile toxins. The toxins act on colonic epithelial cells and immune cells to induce inflammation and tissue damage. TcdA and TcdB disrupt the tight junctions and induce epithelial cell death, causing direct damage to the colonic epithelium. Additionally, the toxins stimulate epithelial cells to release inflammatory mediators that recruit neutrophils to the colonic mucosa. TcdA and TcdB can also enter the lamina propria following the disruption of the epithelial barrier and directly stimulate macrophages, dendritic cells, and mast cells to release inflammatory mediators, which further contribute to inflammation and neutrophil recruitment. Intoxication also results in the activation of enteric neurons and increased production of substance P (SP). SP can induce mast cell degranulation and can stimulate the lamina propria macrophages to release inflammatory cytokines. Prolonged intestinal inflammation can amplify tissue damage and contribute to neutrophil infiltration into the lumen, a key clinical feature of pseudomembranous colitis. The binary toxin CDT, expressed by some C. difficile strains, also induces cytopathic effects that lead to disruption of the tight junctions. Additionally, CDT can suppress a protective host eosinophilic response in the colon and can act synergistically with TcdA and TcdB to increase proinflammatory cytokine production by innate immune cells. Finally, CDT also contributes to C. difficile virulence by inducing the formation of microtubule-based cell protrusions that increase adherence of the bacteria.

Article Snippet: These include a toxoid-based vaccine containing formalin-inactivated TcdA and TcdB from VPI10463 (called Cdiffense) developed by Sanofi Pasteur (Phase III clinical trial identifier: {"type":"clinical-trial","attrs":{"text":"NCT01887912","term_id":"NCT01887912"}} NCT01887912 ), a genetically modified and formalin-inactivated toxoid vaccine developed by Pfizer (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02117570","term_id":"NCT02117570"}} NCT02117570 and {"type":"clinical-trial","attrs":{"text":"NCT02561195","term_id":"NCT02561195"}} NCT02561195 ), and a recombinant fusion protein of TcdA and TcdB C-terminal domains (VLA84 or IC84) developed by Valneva Austria GmbH (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02316470","term_id":"NCT02316470"}} NCT02316470 ) (Martin and Wilcox 2016 ; Feher, Soriano and Mensa 2017 ).

Techniques: Disruption, Activation Assay, Bacteria

Journal: FEMS Microbiology Reviews

Article Title: The role of toxins in Clostridium difficile infection

doi: 10.1093/femsre/fux048

Figure Lengend Snippet: Organization of toxin genes. (A) Schematic representation of the pathogenicity locus (PaLoc). Toxin-encoding genes, tcdA and tcdB, are indicated by blue arrows; regulatory genes are shown in light green (tcdR; positive) or red (tcdC; negative); and holin-encoding gene tcdE is shown in dark green. The direction of the arrows reflects the direction of transcription. TcdR positively regulates its own expression as well as the expression of tcdA and tcdB (indicated by brown arrows). TcdC is an anti-sigma factor that negatively regulates toxin expression by interfering with TcdR function. TcdE is involved in the secretion of toxins. (B) Schematic representation of the binary toxin locus (CdtLoc). CDT-encoding genes, cdtA and cdtB, are shown in blue. The regulatory gene cdtR is shown in light green. CdtR positively regulates the transcription of cdtA and cdtB.

Article Snippet: These include a toxoid-based vaccine containing formalin-inactivated TcdA and TcdB from VPI10463 (called Cdiffense) developed by Sanofi Pasteur (Phase III clinical trial identifier: {"type":"clinical-trial","attrs":{"text":"NCT01887912","term_id":"NCT01887912"}} NCT01887912 ), a genetically modified and formalin-inactivated toxoid vaccine developed by Pfizer (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02117570","term_id":"NCT02117570"}} NCT02117570 and {"type":"clinical-trial","attrs":{"text":"NCT02561195","term_id":"NCT02561195"}} NCT02561195 ), and a recombinant fusion protein of TcdA and TcdB C-terminal domains (VLA84 or IC84) developed by Valneva Austria GmbH (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02316470","term_id":"NCT02316470"}} NCT02316470 ) (Martin and Wilcox 2016 ; Feher, Soriano and Mensa 2017 ).

Techniques: Expressing

Journal: FEMS Microbiology Reviews

Article Title: The role of toxins in Clostridium difficile infection

doi: 10.1093/femsre/fux048

Figure Lengend Snippet: TcdA and TcdB primary structure and mechanism of action. (A) TcdA and TcdB are organized into four functional domains: the glycosyltransferase domain (GTD; pink), the autoprocessing domain (APD; green), the delivery or pore-forming domain (blue) and the combined repetitive oligopeptides domain (CROPS; yellow). (B) The four functional domains contribute to a multistep mechanism of intoxication. TcdA and TcdB bind different cell surface proteins or sugars on the colonic epithelium (step 1) and are internalized by distinct endocytic pathways (step 2). The toxins reach acidified endosomes (step 3) and the low pH triggers a conformational change in the toxin delivery domain, resulting in pore formation and translocation of the GTD (and likely the APD) into the cytosol (step 4). Inositol hexakisphosphate (InsP6) binds and activates the APD, resulting in the cleavage and release of the GTD (step 5). The GTD inactivates Rho family proteins by transferring the glucose moiety (orange squares) from UDP-glucose to the switch I region of the GTPase (step 6). Glucosylation disrupts GTPase signaling and leads to cytopathic ‘rounding’ effects and apoptotic cell death.

Article Snippet: These include a toxoid-based vaccine containing formalin-inactivated TcdA and TcdB from VPI10463 (called Cdiffense) developed by Sanofi Pasteur (Phase III clinical trial identifier: {"type":"clinical-trial","attrs":{"text":"NCT01887912","term_id":"NCT01887912"}} NCT01887912 ), a genetically modified and formalin-inactivated toxoid vaccine developed by Pfizer (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02117570","term_id":"NCT02117570"}} NCT02117570 and {"type":"clinical-trial","attrs":{"text":"NCT02561195","term_id":"NCT02561195"}} NCT02561195 ), and a recombinant fusion protein of TcdA and TcdB C-terminal domains (VLA84 or IC84) developed by Valneva Austria GmbH (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02316470","term_id":"NCT02316470"}} NCT02316470 ) (Martin and Wilcox 2016 ; Feher, Soriano and Mensa 2017 ).

Techniques: Functional Assay, Translocation Assay, Transferring

Journal: FEMS Microbiology Reviews

Article Title: The role of toxins in Clostridium difficile infection

doi: 10.1093/femsre/fux048

Figure Lengend Snippet: Structure of the CROPS domain. (A) The CROPS domains of TcdA and TcdB consist of a series of short repeat (SR, yellow) sequences with interspersed long repeat (LR, purple) sequences. (B) A model of the full TcdA CROPS based on a fragment structure (2F6E) is corroborated by (C) negative stain electron microscopy images of TcdA (left) and TcdB (right). (D) The crystal structure of a CROPS fragment from the TcdA C-terminus (2G7C) shows how trisaccharides (orange carbons) bind at the vertices created at the intersection of an SR and LR.

Article Snippet: These include a toxoid-based vaccine containing formalin-inactivated TcdA and TcdB from VPI10463 (called Cdiffense) developed by Sanofi Pasteur (Phase III clinical trial identifier: {"type":"clinical-trial","attrs":{"text":"NCT01887912","term_id":"NCT01887912"}} NCT01887912 ), a genetically modified and formalin-inactivated toxoid vaccine developed by Pfizer (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02117570","term_id":"NCT02117570"}} NCT02117570 and {"type":"clinical-trial","attrs":{"text":"NCT02561195","term_id":"NCT02561195"}} NCT02561195 ), and a recombinant fusion protein of TcdA and TcdB C-terminal domains (VLA84 or IC84) developed by Valneva Austria GmbH (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02316470","term_id":"NCT02316470"}} NCT02316470 ) (Martin and Wilcox 2016 ; Feher, Soriano and Mensa 2017 ).

Techniques: Staining, Electron Microscopy

Journal: FEMS Microbiology Reviews

Article Title: The role of toxins in Clostridium difficile infection

doi: 10.1093/femsre/fux048

Figure Lengend Snippet: The autoprocessing domain (APD) undergoes a significant conformational change upon binding to InsP6. The crystal structures of the TcdA APD in the (A) absence (4R04) and (B) presence of InsP6 (3HO6) reveal significant changes in the central β-flap structure (blue) and the C-terminal sequence that follows (teal). The structure of the APD in the context of TcdA4-1802 revealed the unexpected requirement for zinc (orange sphere) in TcdA and TcdB autoprocessing activity. Other key residues include Asp 589, His 655 and Cys 700 (side chains depicted with orange carbon atoms). His 759 is located at the tip of the β-flap and is bound to the zinc in the absence of InsP6. It moves significantly upon InsP6 binding.

Article Snippet: These include a toxoid-based vaccine containing formalin-inactivated TcdA and TcdB from VPI10463 (called Cdiffense) developed by Sanofi Pasteur (Phase III clinical trial identifier: {"type":"clinical-trial","attrs":{"text":"NCT01887912","term_id":"NCT01887912"}} NCT01887912 ), a genetically modified and formalin-inactivated toxoid vaccine developed by Pfizer (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02117570","term_id":"NCT02117570"}} NCT02117570 and {"type":"clinical-trial","attrs":{"text":"NCT02561195","term_id":"NCT02561195"}} NCT02561195 ), and a recombinant fusion protein of TcdA and TcdB C-terminal domains (VLA84 or IC84) developed by Valneva Austria GmbH (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02316470","term_id":"NCT02316470"}} NCT02316470 ) (Martin and Wilcox 2016 ; Feher, Soriano and Mensa 2017 ).

Techniques: Binding Assay, Sequencing, Activity Assay

Journal: FEMS Microbiology Reviews

Article Title: The role of toxins in Clostridium difficile infection

doi: 10.1093/femsre/fux048

Figure Lengend Snippet: Cellular effects of C. difficile toxins. The toxins act on colonic epithelial cells and immune cells to induce inflammation and tissue damage. TcdA and TcdB disrupt the tight junctions and induce epithelial cell death, causing direct damage to the colonic epithelium. Additionally, the toxins stimulate epithelial cells to release inflammatory mediators that recruit neutrophils to the colonic mucosa. TcdA and TcdB can also enter the lamina propria following the disruption of the epithelial barrier and directly stimulate macrophages, dendritic cells, and mast cells to release inflammatory mediators, which further contribute to inflammation and neutrophil recruitment. Intoxication also results in the activation of enteric neurons and increased production of substance P (SP). SP can induce mast cell degranulation and can stimulate the lamina propria macrophages to release inflammatory cytokines. Prolonged intestinal inflammation can amplify tissue damage and contribute to neutrophil infiltration into the lumen, a key clinical feature of pseudomembranous colitis. The binary toxin CDT, expressed by some C. difficile strains, also induces cytopathic effects that lead to disruption of the tight junctions. Additionally, CDT can suppress a protective host eosinophilic response in the colon and can act synergistically with TcdA and TcdB to increase proinflammatory cytokine production by innate immune cells. Finally, CDT also contributes to C. difficile virulence by inducing the formation of microtubule-based cell protrusions that increase adherence of the bacteria.

Article Snippet: These include a toxoid-based vaccine containing formalin-inactivated TcdA and TcdB from VPI10463 (called Cdiffense) developed by Sanofi Pasteur (Phase III clinical trial identifier: {"type":"clinical-trial","attrs":{"text":"NCT01887912","term_id":"NCT01887912"}} NCT01887912 ), a genetically modified and formalin-inactivated toxoid vaccine developed by Pfizer (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02117570","term_id":"NCT02117570"}} NCT02117570 and {"type":"clinical-trial","attrs":{"text":"NCT02561195","term_id":"NCT02561195"}} NCT02561195 ), and a recombinant fusion protein of TcdA and TcdB C-terminal domains (VLA84 or IC84) developed by Valneva Austria GmbH (Phase II {"type":"clinical-trial","attrs":{"text":"NCT02316470","term_id":"NCT02316470"}} NCT02316470 ) (Martin and Wilcox 2016 ; Feher, Soriano and Mensa 2017 ).

Techniques: Activation Assay