Combination of Anthrax-Toxin Neutralizing Antibodies: Analysis of Synergism/Antagonism Effect

2010 ◽  
pp. 275-285 ◽  
Author(s):  
Ohad Mazor ◽  
Einat Ben-Arie ◽  
Adva Mechaly ◽  
Ronit Rosenfeld ◽  
Hadar Marcus ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Anthrax Toxin

scholarly journals Binding of the von Willebrand Factor A Domain of Capillary Morphogenesis Protein 2 to Anthrax Protective Antigen Vaccine Reduces Immunogenicity in Mice

mSphere ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Fabiana Freire Mendes de Oliveira ◽  
Sireesha Mamillapalli ◽  
Srinivas Gonti ◽  
Robert N. Brey ◽  
Han Li ◽  
...  
Keyword(s):  
Immune Response ◽  
Von Willebrand Factor ◽  
Neutralizing Antibodies ◽  
Protective Antigen ◽  
Antibody Responses ◽  
Anthrax Toxin ◽  
Anthrax Vaccine ◽  
Capillary Morphogenesis ◽  
Von Willebrand ◽  
Willebrand Factor

ABSTRACT Protective antigen (PA) is a component of anthrax toxin that can elicit toxin-neutralizing antibody responses. PA is also the major antigen in the current vaccine to prevent anthrax, but stability problems with recombinant proteins have complicated the development of new vaccines containing recombinant PA. The relationship between antigen physical stability and immunogenicity is poorly understood, but there are theoretical reasons to think that this parameter can affect immune responses. We investigated the immunogenicity of anthrax PA, in the presence and absence of the soluble von Willebrand factor A domain of the human form of receptor capillary morphogenesis protein 2 (sCMG2), to elicit antibodies to PA in BALB/c mice. Prior studies showed that sCMG2 stabilizes the 83-kDa PA structure to pH, chemical denaturants, temperature, and proteolysis and slows the hydrogen-deuterium exchange rate of histidine residues far from the binding interface. In contrast to a vaccine containing PA without adjuvant, we found that mice immunized with PA in stable complex with sCMG2 showed markedly reduced antibody responses to PA, including toxin-neutralizing antibodies and antibodies to domain 4, which correlated with fewer toxin-neutralizing antibodies. In contrast, mice immunized with PA in concert with a nonbinding mutant of sCMG2 (D50A) showed anti-PA antibody responses similar to those observed with PA alone. Our results suggest that addition of sCMG2 to a PA vaccine formulation is likely to result in a significantly diminished immune response, but we discuss the multitude of factors that could contribute to reduced immunogenicity. IMPORTANCE The anthrax toxin PA is the major immunogen in the current anthrax vaccine (anthrax vaccine adsorbed). Improving the anthrax vaccine for avoidance of a cold chain necessitates improvements in the thermodynamic stability of PA. We address how stabilizing PA using sCMG2 affects PA immunogenicity in BALB/c mice. Although the stability of PA is increased by binding to sCMG2, PA immunogenicity is decreased. This study emphasizes that, while binding of a ligand retains or improves conformational stability without affecting the native sequence, epitope recognition or processing may be affected, abrogating an effective immune response.

scholarly journals Progress towards the Development of a NEAT Vaccine for Anthrax II: Immunogen Specificity and Alum Effectiveness in an Inhalational Model

2020 ◽  
Vol 88 (8) ◽  
Author(s):  
Joseph Jelinski ◽  
Austen Terwilliger ◽  
Sabrina Green ◽  
Anthony Maresso
Keyword(s):  
Neutralizing Antibodies ◽  
Protective Antigen ◽  
Anthrax Toxin ◽  
Cell Binding ◽  
Lethal Challenge ◽  
Anthrax Vaccine ◽  
Content Type ◽  
Heme Transport ◽  
Bacillus Spores ◽  
Culture Supernatants

ABSTRACT Bacillus anthracis is the causative agent of anthrax disease, presents with high mortality, and has been at the center of bioweapon efforts. The only currently U.S. FDA-approved vaccine to prevent anthrax in humans is anthrax vaccine adsorbed (AVA), which is protective in several animal models and induces neutralizing antibodies against protective antigen (PA), the cell-binding component of anthrax toxin. However, AVA requires a five-course regimen to induce immunity, along with an annual booster, and is composed of undefined culture supernatants from a PA-secreting strain. In addition, it appears to be ineffective against strains that lack anthrax toxin. Here, we investigated a vaccine formulation consisting of recombinant proteins from a surface-localized heme transport system containing near-iron transporter (NEAT) domains and its efficacy as a vaccine for anthrax disease. The cocktail of five NEAT domains was protective against a lethal challenge of inhaled bacillus spores at 3 and 28 weeks after vaccination. The reduction of the formulation to three NEATs (IsdX1, IsdX2, and Bslk) was as effective as a five-NEAT domain cocktail. The adjuvant alum, approved for use in humans, was as protective as Freund’s Adjuvant, and protective vaccination correlated with increased anti-NEAT antibody reactivity and reduced bacterial levels in organs. Finally, the passive transfer of anti-NEAT antisera reduced mortality and disease severity, suggesting the protective component is comprised of antibodies. Collectively, these results provide evidence that a vaccine based upon recombinant NEAT proteins should be considered in the development of a next-generation anthrax vaccine.

scholarly journals Neutralizing Monoclonal Antibodies Directed against Defined Linear Epitopes on Domain 4 of Anthrax Protective Antigen

2009 ◽  
Vol 77 (11) ◽  
pp. 4859-4867 ◽  
Author(s):  
Cassandra D. Kelly-Cirino ◽  
Nicholas J. Mantis
Keyword(s):  
Neutralizing Antibodies ◽  
Protective Antigen ◽  
Solid Phase ◽  
Anthrax Toxin ◽  
Future Application ◽  
Lethal Challenge ◽  
Anthrax Protective Antigen ◽  
Solid Phase Binding ◽  
Domain 4

ABSTRACT The anthrax protective antigen (PA) is the receptor-binding subunit common to lethal toxin (LT) and edema toxin (ET), which are responsible for the high mortality rates associated with inhalational Bacillus anthracis infection. Although recombinant PA (rPA) is likely to be an important constituent of any future anthrax vaccine, evaluation of the efficacies of the various candidate rPA vaccines is currently difficult, because the specific B-cell epitopes involved in toxin neutralization have not been completely defined. In this study, we describe the identification and characterization of two murine monoclonal immunoglobulin G1 antibodies (MAbs), 1-F1 and 2-B12, which recognize distinct linear neutralizing epitopes on domain 4 of PA. 1-F1 recognized a 12-mer peptide corresponding to residues 692 to 703; this epitope maps to a region of domain 4 known to interact with the anthrax toxin receptor CMG-2 and within a conformation-dependent epitope recognized by the well-characterized neutralizing MAb 14B7. As expected, 1-F1 blocked PA's ability to associate with CMG-2 in an in vitro solid-phase binding assay, and it protected murine macrophage cells from intoxication with LT. 2-B12 recognized a 12-mer peptide corresponding to residues 716 to 727, an epitope located immediately adjacent to the core 14B7 binding site and a stretch of amino acids not previously identified as a target of neutralizing antibodies. 2-B12 was as effective as 1-F1 in neutralizing LT in vitro, although it only partially inhibited PA binding to its receptor. Mice passively administered 1-F1 or 2-B12 were partially protected against a lethal challenge with LT. These results advance our fundamental understanding of the mechanisms by which antibodies neutralize anthrax toxin and may have future application in the evaluation of candidate rPA vaccines.

Third anthrax toxin revealed

Nature ◽  
2002 ◽  
Author(s):  
Tom Clarke
Keyword(s):  
Anthrax Toxin

Endothelial Cell Protein S Synthesis Is Upregulated by the Complex of IL-6 and Soluble IL-6 Receptor

1997 ◽  
Vol 77 (05) ◽  
pp. 1014-1019 ◽  
Author(s):  
W Craig Hooper ◽  
Donald J Phillips ◽  
Bruce L Evatt
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Cell Line ◽  
Neutralizing Antibodies ◽  
Hepatoma Cell ◽  
Protein S ◽  
Oncostatin M ◽  
Cell Protein ◽  
Microvascular Endothelial Cell ◽  
Hepatoma Cell Line

SummaryWe have recently demonstrated that the proinflammatory cytokine, interleukin-6 (IL-6), could upregulate the production of protein S in the human hepatoma cell line, HepG-2, but not in endothelial cells. In this study, we have demonstrated that the combination of exogenous IL-6 and soluble IL-6 receptor (sIL-6R) could significantly upregulate protein S production in both primary human umbilical vein endothelial cells (HUVEC) and in the immortalized human microvascular endothelial cell line, HMEC-1. The IL-6/sIL-6R complex was also able to rapidly induce tyrosine phosphorylation of the IL-6 transducer, gpl30. Neutralizing antibodies directed against either IL-6 or gpl30 blocked protein S upregulation by the IL-6/sIL-6R complex. It was also observed that exogenous sIL-6R could also upregulate protein S by forming a complex with IL-6 constitutively produced by the endothelial cell. Two other cytokines which also utilize the gpl30 receptor, oncostatin M (OSM) and leukemia inhibitory factor (LIF), were also able to upregulate endothelial cell protein S. This study demonstrates a mechanism that allows endothelial cells to respond to IL-6 and also illustrates the potential importance of circulating soluble receptors in the regulation of the anticoagulation pathway.

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