Toxins

Research

Jump to: Review

1836 KiB

Open AccessArticle

Role of Fc in Antibody-Mediated Protection from Ricin Toxin

by Seth. H. Pincus, Anushka Das, Kejing Song, Grace A. Maresh, Miriam Corti and Jody Berry

Toxins 2014, 6(5), 1512-1525; https://doi.org/10.3390/toxins6051512 - 7 May 2014

Cited by 19 | Viewed by 5952

Abstract

We have studied the role of the antibody (Ab) Fc region in mediating protection from ricin toxicity. We compared the in vitro and in vivo effects of intact Ig and of Fab fragments derived from two different neutralizing Ab preparations, one monoclonal, the [...] Read more.

We have studied the role of the antibody (Ab) Fc region in mediating protection from ricin toxicity. We compared the in vitro and in vivo effects of intact Ig and of Fab fragments derived from two different neutralizing Ab preparations, one monoclonal, the other polyclonal. Consistent results were obtained from each, showing little difference between Ig and Fab in terms of antigen binding and in vitro neutralization, but with relatively large differences in protection of animals. We also studied whether importing Ab into the cell by Fc receptors enhanced the intracellular neutralization of ricin toxin. We found that the imported Ab was found in the ER and Golgi, a compartment traversed by ricin, as it traffics through the cell, but intracellular Ab did not contribute to the neutralization of ricin. These results indicate that the Fc region of antibody is important for in vivo protection, although the mechanism of enhanced protection by intact Ig does not appear to operate at the single cell level. When using xenogeneic antibodies, the diminished immunogenicity of Fab/F(ab’)₂ preparations should be balanced against possible loss of protective efficacy. Full article

(This article belongs to the Special Issue Toxin-Antibody Interactions)

► Show Figures

Figure 1

471 KiB

Open AccessArticle

Recombinant Clostridium difficile Toxin Fragments as Carrier Protein for PSII Surface Polysaccharide Preserve Their Neutralizing Activity

by Maria R. Romano, Rosanna Leuzzi, Emilia Cappelletti, Marta Tontini, Alberto Nilo, Daniela Proietti, Francesco Berti, Paolo Costantino, Roberto Adamo and Maria Scarselli

Toxins 2014, 6(4), 1385-1396; https://doi.org/10.3390/toxins6041385 - 22 Apr 2014

Cited by 23 | Viewed by 6657

Abstract

Clostridium difficile is a Gram-positive bacterium and is the most commonly diagnosed cause of hospital-associated and antimicrobial-associated diarrhea. Despite the emergence of epidemic C. difficile strains having led to an increase in the incidence of the disease, a vaccine against this pathogen is [...] Read more.

Clostridium difficile is a Gram-positive bacterium and is the most commonly diagnosed cause of hospital-associated and antimicrobial-associated diarrhea. Despite the emergence of epidemic C. difficile strains having led to an increase in the incidence of the disease, a vaccine against this pathogen is not currently available. C. difficile strains produce two main toxins (TcdA and TcdB) and express three highly complex cell-surface polysaccharides (PSI, PSII and PSIII). PSII is the more abundantly expressed by most C. difficile ribotypes offering the opportunity of the development of a carbohydrate-based vaccine. In this paper, we evaluate the efficacy, in naive mice model, of PSII glycoconjugates where recombinant toxins A and B fragments (TcdA_B2 and TcdB_GT respectively) have been used as carriers. Both glycoconjugates elicited IgG titers anti-PSII although only the TcdB_GT conjugate induced a response comparable to that obtained with CRM₁₉₇. Moreover, TcdA_B2 and TcdB_GT conjugated to PSII retained the ability to elicit IgG with neutralizing activity against the respective toxins. These results are a crucial proof of concept for the development of glycoconjugate vaccines against C. difficile infection (CDI) that combine different C. difficile antigens to potentially prevent bacterial colonization of the gut and neutralize toxin activity. Full article

(This article belongs to the Special Issue Toxin-Antibody Interactions)

► Show Figures

Figure 1

552 KiB

Open AccessArticle

Active Immunity Induced by Passive IgG Post-Exposure Protection against Ricin

by Charles Chen Hu, Junfei Yin, Damon Chau, John W. Cherwonogrodzky and Wei-Gang Hu

Toxins 2014, 6(1), 380-393; https://doi.org/10.3390/toxins6010380 - 21 Jan 2014

Cited by 5 | Viewed by 6853

Abstract

Therapeutic antibodies can confer an instant protection against biothreat agents when administered. In this study, intact IgG and F(ab’)2 from goat anti-ricin hyperimmune sera were compared for the protection against lethal ricin mediated intoxication. Similar ricin-binding affinities and neutralizing activities in vitro were [...] Read more.

Therapeutic antibodies can confer an instant protection against biothreat agents when administered. In this study, intact IgG and F(ab’)2 from goat anti-ricin hyperimmune sera were compared for the protection against lethal ricin mediated intoxication. Similar ricin-binding affinities and neutralizing activities in vitro were observed between IgG and F(ab’)2 when compared at the same molar concentration. In a murine ricin intoxication model, both IgG and F(ab’)2 could rescue 100% of the mice by one dose (3 nmol) administration of antibodies 1 hour after 5 × LD50 ricin challenge. Nine days later, when the rescued mice received a second ricin challenge (5 × LD50), only the IgG-treated mice survived; the F(ab’)2-treated mice did not. The experimental design excluded the possibility of residual goat IgG responsible for the protection against the second ricin challenge. Results confirmed that the active immunity against ricin in mice was induced quickly following the passive delivery of a single dose of goat IgG post-exposure. Furthermore, it was demonstrated that the induced active immunity against ricin in mice lasted at least 5 months. Therefore, passive IgG therapy not only provides immediate protection to the victim after ricin exposure, but also elicits an active immunity against ricin that subsequently results in long term protection. Full article

(This article belongs to the Special Issue Toxin-Antibody Interactions)

► Show Figures

Figure 1

785 KiB

Open AccessArticle

Cloning and Characterization of a Hybridoma Secreting a 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-Specific Monoclonal Antibody and Recombinant F(ab)

by Heather Wanczyk, Tolga Barker, Debra Rood, Daniel I. Zapata, Amy R. Howell, Stewart K. Richardson, John Zinckgraf, Gregory P. Marusov, Michael A. Lynes and Lawrence K. Silbart

Toxins 2013, 5(3), 568-589; https://doi.org/10.3390/toxins5030568 - 19 Mar 2013

Cited by 2 | Viewed by 9767

Abstract

Smokeless tobacco products have been associated with increased risks of oro-pharyngeal cancers, due in part to the presence of tobacco-specific nitrosamines (TSNAs) such as 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). These potent carcinogens are formed during tobacco curing and as a result of direct nitrosation reactions that [...] Read more.

Smokeless tobacco products have been associated with increased risks of oro-pharyngeal cancers, due in part to the presence of tobacco-specific nitrosamines (TSNAs) such as 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). These potent carcinogens are formed during tobacco curing and as a result of direct nitrosation reactions that occur in the oral cavity. In the current work we describe the isolation and characterization of a hybridoma secreting a high-affinity, NNK-specific monoclonal antibody. A structurally-related benzoyl derivative was synthesized to facilitate coupling to NNK-carrier proteins, which were characterized for the presence of the N-nitroso group using the Griess reaction, and used to immunize BALB/c mice. Splenocytes from mice bearing NNK-specific antibodies were used to create hybridomas. Out of four, one was selected for subcloning and characterization. Approximately 99% of the monoclonal antibodies from this clone were competitively displaced from plate-bound NNKB conjugates in the presence of free NNK. The affinity of the monoclonal antibody to the NNKB conjugates was K_d = 2.93 nM as determined by surface plasmon resonance. Free nicotine was a poor competitor for the NNKB binding site. The heavy and light chain antibody F(ab) fragments were cloned, sequenced and inserted in tandem into an expression vector, with an FMDV Furin 2A cleavage site between them. Expression in HEK 293 cells revealed a functional F(ab) with similar binding features to that of the parent hybridoma. This study lays the groundwork for synthesizing transgenic tobacco that expresses carcinogen-sequestration properties, thereby rendering it less harmful to consumers. Full article

(This article belongs to the Special Issue Toxin-Antibody Interactions)

► Show Figures

Figure 1

562 KiB

Open AccessArticle

Sheep Monoclonal Antibodies Prevent Systemic Effects of Botulinum Neurotoxin A1

by Jean Mukherjee, Chase McCann, Kwasi Ofori, Julia Hill, Karen Baldwin, Charles B. Shoemaker, Peter Harrison and Saul Tzipori

Toxins 2012, 4(12), 1565-1581; https://doi.org/10.3390/toxins4121565 - 19 Dec 2012

Cited by 6 | Viewed by 8291

Abstract

Botulinum neurotoxin (BoNT) is responsible for causing botulism, a potentially fatal disease characterized by paralysis of skeletal muscle. Existing specific treatments include polyclonal antisera derived from immunized humans or horses. Both preparations have similar drawbacks, including limited supply, risk of adverse effects and [...] Read more.

Botulinum neurotoxin (BoNT) is responsible for causing botulism, a potentially fatal disease characterized by paralysis of skeletal muscle. Existing specific treatments include polyclonal antisera derived from immunized humans or horses. Both preparations have similar drawbacks, including limited supply, risk of adverse effects and batch to batch variation. Here, we describe a panel of six highly protective sheep monoclonal antibodies (SMAbs) derived from sheep immunized with BoNT/A1 toxoid (SMAbs 2G11, 4F7) or BoNT/A1 heavy chain C-terminus (HcC) (SMAbs 1G4, 5E2, 5F7, 16F9) with or without subsequent challenge immunization with BoNT/A1 toxin. Although each SMAb bound BoNT/A1 toxin, differences in specificity for native and recombinant constituents of BoNT/A1 were observed. Structural differences were suggested by pI (5E2 = 8.2; 2G11 = 7.1; 4F7 = 8.8; 1G4 = 7.4; 5F7 = 8.0; 16F9 = 5.1). SMAb protective efficacy vs. 10,000 LD50 BoNT/A1 was evaluated using the mouse lethality assay. Although not protective alone, divalent and trivalent combinations of SMabs, IG4, 5F7 and/or 16F9 were highly protective. Divalent combinations containing 0.5–4 μg/SMAb (1–8 μg total SMAb) were 100% protective against death with only mild signs of botulism observed; relative efficacy of each combination was 1G4 + 5F7 > 1G4 + 16F9 >> 5F7 + 16F9. The trivalent combination of 1G4 + 5F7 + 16F9 at 0.25 μg/SMAb (0.75 μg total SMAb) was 100% protective against clinical signs and death. These results reflect levels of protective potency not reported previously. Full article

(This article belongs to the Special Issue Toxin-Antibody Interactions)

► Show Figures

Figure 1

330 KiB

Open AccessArticle

MHC Class II and Non-MHC Class II Genes Differentially Influence Humoral Immunity to Bacillus anthracis Lethal Factor and Protective Antigen

by Lori Garman, Eric K. Dumas, Sridevi Kurella, Jonathan J. Hunt, Sherry R. Crowe, Melissa L. Nguyen, Philip M. Cox, Judith A. James and A. Darise Farris

Toxins 2012, 4(12), 1451-1467; https://doi.org/10.3390/toxins4121451 - 5 Dec 2012

Cited by 8 | Viewed by 6508

Abstract

Anthrax Lethal Toxin consists of Protective Antigen (PA) and Lethal Factor (LF), and current vaccination strategies focus on eliciting antibodies to PA. In human vaccination, the response to PA can vary greatly, and the response is often directed toward non-neutralizing epitopes. Variable vaccine [...] Read more.

Anthrax Lethal Toxin consists of Protective Antigen (PA) and Lethal Factor (LF), and current vaccination strategies focus on eliciting antibodies to PA. In human vaccination, the response to PA can vary greatly, and the response is often directed toward non-neutralizing epitopes. Variable vaccine responses have been shown to be due in part to genetic differences in individuals, with both MHC class II and other genes playing roles. Here, we investigated the relative contribution of MHC class II versus non-MHC class II genes in the humoral response to PA and LF immunization using three immunized strains of inbred mice: A/J (H-2k at the MHC class II locus), B6 (H-2b), and B6.H2k (H-2k). IgG antibody titers to LF were controlled primarily by the MHC class II locus, whereas IgG titers to PA were strongly influenced by the non-MHC class II genetic background. Conversely, the humoral fine specificity of reactivity to LF appeared to be controlled primarily through non-MHC class II genes, while the specificity of reactivity to PA was more dependent on MHC class II. Common epitopes, reactive in all strains, occurred in both LF and PA responses. These results demonstrate that MHC class II differentially influences humoral immune responses to LF and PA. Full article

(This article belongs to the Special Issue Toxin-Antibody Interactions)

► Show Figures

Figure 1

1379 KiB

Open AccessArticle

Interaction between Shiga Toxin and Monoclonal Antibodies: Binding Characteristics and in Vitro Neutralizing Abilities

by Letícia B. Rocha, Daniela E. Luz, Claudia T. P. Moraes, Andressa Caravelli, Irene Fernandes, Beatriz E. C. Guth, Denise S. P. Q. Horton and Roxane M. F. Piazza

Toxins 2012, 4(9), 729-747; https://doi.org/10.3390/toxins4090729 - 18 Sep 2012

Cited by 32 | Viewed by 7741

Abstract

Monoclonal antibodies (MAbs) have been employed either for diagnosis or treatment of infections caused by different pathogens. Specifically for Shiga toxin-producing Escherichia coli (STEC), numerous immunoassays have been developed for STEC diagnosis, showing variability in sensitivity and specificity when evaluated by reference laboratories, [...] Read more.

Monoclonal antibodies (MAbs) have been employed either for diagnosis or treatment of infections caused by different pathogens. Specifically for Shiga toxin-producing Escherichia coli (STEC), numerous immunoassays have been developed for STEC diagnosis, showing variability in sensitivity and specificity when evaluated by reference laboratories, and no therapy or vaccines are currently approved. Thus, the aim of this work was the characterization of the interaction between MAbs against Stx1 and Stx2 toxins and their neutralizing abilities to enable their use as tools for diagnosis and therapy. The selected clones designated 3E2 (anti-Stx1) and 2E11 (anti-Stx2) were classified as IgG1. 3E2 recognized the B subunit of Stx1 with an affinity constant of 2.5 × 10⁻¹⁰ M, detected as little as 6.2 ng of Stx1 and was stable up to 50 ºC. In contrast, 2E11 recognized the A subunit of Stx2, was stable up to 70 ºC, had a high dissociation constant of 6.1 × 10⁻¹⁰ M, and detected as little as 12.5 ng of Stx2. Neutralization tests showed that 160 ng of 3E2 MAb inhibited 80% of Stx1 activity and 500 µg 2E11 MAb were required for 60% inhibition of Stx2 activity. These MAb amounts reversed 25 to 80% of the cytotoxicity triggered by different STEC isolates. In conclusion, these MAbs show suitable characteristics for their use in STEC diagnosis and encourage future studies to investigate their protective efficacy. Full article

(This article belongs to the Special Issue Toxin-Antibody Interactions)

► Show Figures

Figure 1

1125 KiB

Open AccessArticle

Humanized-Single Domain Antibodies (VH/V_HH) that Bound Specifically to Naja kaouthia Phospholipase A2 and Neutralized the Enzymatic Activity

by Charnwit Chavanayarn, Jeeraphong Thanongsaksrikul, Kanyarat Thueng-in, Kunan Bangphoomi, Nitat Sookrung and Wanpen Chaicumpa

Toxins 2012, 4(7), 554-567; https://doi.org/10.3390/toxins4070554 - 19 Jul 2012

Cited by 41 | Viewed by 9321

Abstract

Naja kaouthia (monocled cobra) venom contains many isoforms of secreted phospholipase A2 (sPLA₂). The PLA₂ exerts several pharmacologic and toxic effects in the snake bitten subject, dependent or independent on the enzymatic activity. N. kaouthia venom appeared in two protein [...] Read more.

Naja kaouthia (monocled cobra) venom contains many isoforms of secreted phospholipase A2 (sPLA₂). The PLA₂ exerts several pharmacologic and toxic effects in the snake bitten subject, dependent or independent on the enzymatic activity. N. kaouthia venom appeared in two protein profiles, P3 and P5, after fractionating the venom by ion exchange column chromatography. In this study, phage clones displaying humanized-camel single domain antibodies (VH/V_HH) that bound specifically to the P3 and P5 were selected from a humanized-camel VH/V_HH phage display library. Two phagemid transfected E. coli clones (P3-1 and P3-3) produced humanized-V_HH, while another clone (P3-7) produced humanized-VH. At the optimal venom:antibody ratio, the VH/V_HH purified from the E. coli homogenates neutralized PLA₂ enzyme activity comparable to the horse immune serum against the N. kaouthia holo-venom. Homology modeling and molecular docking revealed that the VH/V_HH covered the areas around the PLA₂ catalytic groove and inserted their Complementarity Determining Regions (CDRs) into the enzymatic cleft. It is envisaged that the VH/V_HH would ameliorate/abrogate the principal toxicity of the venom PLA₂ (membrane phospholipid catabolism leading to cellular and subcellular membrane damage which consequently causes hemolysis, hemorrhage, and dermo-/myo-necrosis), if they were used for passive immunotherapy of the cobra bitten victim. The speculation needs further investigations. Full article

(This article belongs to the Special Issue Toxin-Antibody Interactions)

► Show Figures

Figure 1

Review

Jump to: Research

285 KiB

Open AccessReview

Designing Vaccines to Neutralize Effective Toxin Delivery by Enterotoxigenic Escherichia coli

by James M. Fleckenstein and Alaullah Sheikh

Toxins 2014, 6(6), 1799-1812; https://doi.org/10.3390/toxins6061799 - 10 Jun 2014

Cited by 10 | Viewed by 5536

Abstract

Enterotoxigenic Escherichia coli (ETEC) are a leading cause of diarrheal illness in developing countries. Despite the discovery of these pathogens as a cause of cholera-like diarrhea over 40 years ago, and decades of vaccine development effort, there remains no broadly protective ETEC vaccine. [...] Read more.

Enterotoxigenic Escherichia coli (ETEC) are a leading cause of diarrheal illness in developing countries. Despite the discovery of these pathogens as a cause of cholera-like diarrhea over 40 years ago, and decades of vaccine development effort, there remains no broadly protective ETEC vaccine. The discovery of new virulence proteins and an improved appreciation of the complexity of the molecular events required for effective toxin delivery may provide additional avenues to pursue in development of an effective vaccine to prevent severe diarrhea caused by these important pathogens. Full article

(This article belongs to the Special Issue Toxin-Antibody Interactions)

2499 KiB

Open AccessReview

Recent Developments in Antibody-Based Assays for the Detection of Bacterial Toxins

by Kui Zhu, Richard Dietrich, Andrea Didier, Dominik Doyscher and Erwin Märtlbauer

Toxins 2014, 6(4), 1325-1348; https://doi.org/10.3390/toxins6041325 - 11 Apr 2014

Cited by 47 | Viewed by 16378

Abstract

Considering the urgent demand for rapid and accurate determination of bacterial toxins and the recent promising developments in nanotechnology and microfluidics, this review summarizes new achievements of the past five years. Firstly, bacterial toxins will be categorized according to their antibody binding properties [...] Read more.

Considering the urgent demand for rapid and accurate determination of bacterial toxins and the recent promising developments in nanotechnology and microfluidics, this review summarizes new achievements of the past five years. Firstly, bacterial toxins will be categorized according to their antibody binding properties into low and high molecular weight compounds. Secondly, the types of antibodies and new techniques for producing antibodies are discussed, including poly- and mono-clonal antibodies, single-chain variable fragments (scFv), as well as heavy-chain and recombinant antibodies. Thirdly, the use of different nanomaterials, such as gold nanoparticles (AuNPs), magnetic nanoparticles (MNPs), quantum dots (QDs) and carbon nanomaterials (graphene and carbon nanotube), for labeling antibodies and toxins or for readout techniques will be summarized. Fourthly, microscale analysis or minimized devices, for example microfluidics or lab-on-a-chip (LOC), which have attracted increasing attention in combination with immunoassays for the robust detection or point-of-care testing (POCT), will be reviewed. Finally, some new materials and analytical strategies, which might be promising for analyzing toxins in the near future, will be shortly introduced. Full article

(This article belongs to the Special Issue Toxin-Antibody Interactions)

► Show Figures

Figure 1

462 KiB

Open AccessReview

Towards Clinical Applications of Anti-endotoxin Antibodies; A Re-appraisal of the Disconnect

by James C. Hurley

Toxins 2013, 5(12), 2589-2620; https://doi.org/10.3390/toxins5122589 - 18 Dec 2013

Cited by 25 | Viewed by 8869

Abstract

Endotoxin is a potent mediator of a broad range of patho-physiological effects in humans. It is present in all Gram negative (GN) bacteria. It would be expected that anti-endotoxin therapies, whether antibody based or not, would have an important adjuvant therapeutic role along [...] Read more.

Endotoxin is a potent mediator of a broad range of patho-physiological effects in humans. It is present in all Gram negative (GN) bacteria. It would be expected that anti-endotoxin therapies, whether antibody based or not, would have an important adjuvant therapeutic role along with antibiotics and other supportive therapies for GN infections. Indeed there is an extensive literature relating to both pre-clinical and clinical studies of anti-endotoxin antibodies. However, the extent of disconnect between the generally successful pre-clinical studies versus the failures of the numerous large clinical trials of antibody based and other anti-endotoxin therapies is under-appreciated and unexplained. Seeking a reconciliation of this disconnect is not an abstract academic question as clinical trials of interventions to reduce levels of endotoxemia levels are ongoing. The aim of this review is to examine new insights into the complex relationship between endotoxemia and sepsis in an attempt to bridge this disconnect. Several new factors to consider in this reappraisal include the frequency and types of GN bacteremia and the underlying mortality risk in the various study populations. For a range of reasons, endotoxemia can no longer be considered as a single entity. There are old clinical trials which warrant a re-appraisal in light of these recent advances in the understanding of the structure-function relationship of endotoxin. Fundamentally however, the disconnect not only remains, it has enlarged. Full article

(This article belongs to the Special Issue Toxin-Antibody Interactions)

► Show Figures

Figure 1

526 KiB

Open AccessReview

Monoclonal Antibodies and Toxins—A Perspective on Function and Isotype

by Siu-Kei Chow and Arturo Casadevall

Toxins 2012, 4(6), 430-454; https://doi.org/10.3390/toxins4060430 - 11 Jun 2012

Cited by 39 | Viewed by 8729

Abstract

Antibody therapy remains the only effective treatment for toxin-mediated diseases. The development of hybridoma technology has allowed the isolation of monoclonal antibodies (mAbs) with high specificity and defined properties, and numerous mAbs have been purified and characterized for their protective efficacy against different [...] Read more.

Antibody therapy remains the only effective treatment for toxin-mediated diseases. The development of hybridoma technology has allowed the isolation of monoclonal antibodies (mAbs) with high specificity and defined properties, and numerous mAbs have been purified and characterized for their protective efficacy against different toxins. This review summarizes the mAb studies for 6 toxins—Shiga toxin, pertussis toxin, anthrax toxin, ricin toxin, botulinum toxin, and Staphylococcal enterotoxin B (SEB)—and analyzes the prevalence of mAb functions and their isotypes. Here we show that most toxin-binding mAbs resulted from immunization are non-protective and that mAbs with potential therapeutic use are preferably characterized. Various common practices and caveats of protection studies are discussed, with the goal of providing insights for the design of future research on antibody-toxin interactions. Full article

(This article belongs to the Special Issue Toxin-Antibody Interactions)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Toxin-Antibody Interactions

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (12 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI