/pdf/anthrax-as-a-biological-weapon-medical-and-public-health-27tg6s6vfv.pdf

Anthrax as a Biological Weapon: Medical and Public Health Management

Staphylococcus aureus and Staphylococcus epidermidis both synthesize the surface polysaccharide poly-N-acetyl-β-(1-6)-glucosamine (PNAG), which is produced in vitro with a high level (>90%) of the amino groups substituted by acetate. Here, we examined the role of the acetate substituents of PNAG in generating opsonic and protective antibodies. PNAG and a deacetylated form of the antigen (dPNAG; 15% acetylation) were conjugated to the carrier protein diphtheria toxoid (DT) and used to immunize animals. Mice responded in a dose-dependent fashion to both conjugate vaccines, with maximum antibody titers observed at the highest dose and 4 weeks after the last of three weekly immunizations. PNAG-DT and dPNAG-DT vaccines were also very immunogenic in rabbits. Antibodies raised to the conjugate vaccines in rabbits mediated the opsonic killing of various staphylococcal strains, but the specificity of the opsonic killing was primarily to dPNAG, as this antigen inhibited the killing of S. aureus strains by both PNAG- and dPNAG-specific antibodies. Passive immunization of mice with anti-dPNAG-DT rabbit sera showed significant levels of clearance of S. aureus from the blood (54 to 91%) compared to control mice immunized with normal rabbit sera, whereas PNAG-specific antibodies were ineffective at clearing S. aureus. Passive immunization of mice with a goat antiserum raised to the dPNAG-DT vaccine protected against a lethal dose of three different S. aureus strains. Overall, these data show that immunization of animals with a conjugate vaccine of dPNAG elicit antibodies that mediated opsonic killing and protected against S. aureus infection, including capsular polysaccharide types 5 and 8 and an untypable strain.

https://iai.asm.org/content/iai/73/10/6752.full.pdf

Comparative Opsonic and Protective Activities of Staphylococcus aureus Conjugate Vaccines Containing Native or Deacetylated Staphylococcal Poly-N-Acetyl-β-(1-6)-Glucosamine

Vaccines against the category B toxins: Staphylococcal enterotoxin B, epsilon toxin and ricin.

A new sandwich-type electrochemical immunoassay for ultrasensitive detection of staphylococcal enterotoxin B (SEB) in food was developed using horseradish peroxidase-nanosilica-doped multiwalled carbon nanotubes (HRPSiCNTs) for signal amplification. Rabbit polyclonal anti-SEB antibodies immobilized on the screen-printed carbon electrode (SPCE) and covalently bound to the HRPSiCNTs were used as capture antibodies and detection antibodies, respectively. In the presence of SEB analyte, the sandwich-type immunocomplex could be formed between the immobilized anti-SEB on the SPCE and anti-SEB-labeled HRPSiCNTs, and the carried HRP could catalyze the electrochemical reduction of H2O2 with the help of thionine. The high content of HRP in the HRPSiCNTs could greatly amplify the electrochemical signal. Under optimal conditions, the reduction current increased with the increase of SEB in the sample, and exhibited a dynamic range of 0.05−15 ng/mL with a low detection limit (LOD) of 10 pg/mL SEB (at 3σ). Intra- and in...

Ultrasensitive Electrochemical Immunoassay of Staphylococcal Enterotoxin B in Food Using Enzyme-Nanosilica-Doped Carbon Nanotubes for Signal Amplification

We report a highly sensitive and rapid method for the detection of Staphylococcus aureus enterotoxin B (SEB) at picogram levels using a piezoelectric-excited millimeter-sized cantilever (PEMC) sensor. Affinity purified polyclonal antibody to Staphylococcal enterotoxin B (anti-SEB) was immobilized on the aminated cantilever glass surface, followed by exposure of SEB containing samples flowing at a rate of 1 mL/min. The binding of SEB was measured by monitoring the sensor's fundamental resonance frequency. The fundamental frequencies in air and under liquid immersion were 17.50 ± 0.01 kHz and 10.37 ± 0.01 kHz, respectively. Binding of SEB to the sensor surface resulted in an exponential decrease of the resonance frequency and reached a steady state frequency change of 31 ± 1 Hz ( n  = 2) and 208 ± 1 Hz ( n  = 2) corresponding to SEB concentrations of 50 pg/mL and 12.5 ng/mL, respectively. In each experiment, the bound SEB was released by a pH 2.0 HCl/PBS solution and the sensor response was nearly identical to the frequency change caused by attachment. Full antibody surface regeneration was obtained after the release by rinsing the sensor with PBS pH 7.4. We report the detection limit of PEMC sensors to SEB is between 12.5 pg/mL and 50 pg/mL.

Detection of Staphylococcus enterotoxin B at picogram levels using piezoelectric-excited millimeter-sized cantilever sensors

Nonhuman primates (NHPs) and rabbits are the animal models most commonly used to evaluate the efficacy of medical countermeasures against anthrax in support of licensure under the FDA's "Animal Rule." However, a need for an alternative animal model may arise in certain cases. The development of such an alternative model requires a thorough understanding of the course and manifestation of experimental anthrax disease induced under controlled conditions in the proposed animal species. The guinea pig, which has been used extensively for anthrax pathogenesis studies and anthrax vaccine potency testing, is a good candidate for such an alternative model. This study was aimed at determining the median lethal dose (LD50) of the Bacillus anthracis Ames strain in guinea pigs and investigating the natural history, pathophysiology, and pathology of inhalational anthrax in this animal model following nose-only aerosol exposure. The inhaled LD50 of aerosolized Ames strain spores in guinea pigs was determined to be 5.0 × 10(4) spores. Aerosol challenge of guinea pigs resulted in inhalational anthrax with death occurring between 46 and 71 h postchallenge. The first clinical signs appeared as early as 36 h postchallenge. Cardiovascular function declined starting at 20 h postexposure. Hematogenous dissemination of bacteria was observed microscopically in multiple organs and tissues as early as 24 h postchallenge. Other histopathologic findings typical of disseminated anthrax included suppurative (heterophilic) inflammation, edema, fibrin, necrosis, and/or hemorrhage in the spleen, lungs, and regional lymph nodes and lymphocyte depletion and/or lymphocytolysis in the spleen and lymph nodes. This study demonstrated that the course of inhalational anthrax disease and the resulting pathology in guinea pigs are similar to those seen in rabbits and NHPs, as well as in humans.

https://journals.asm.org/doi/pdf/10.1128/IAI.01289-12

Pathology and Pathophysiology of Inhalational Anthrax in a Guinea Pig Model

Currently available murine staphylococcal enterotoxin B (SEB) shock models require pretreatment with various agents to increase mouse sensitivity to SEB. This study was performed to show that C3H/H...

Murine Lethal Toxic Shock Caused by Intranasal Administration of Staphylococcal Enterotoxin B

Bacillus anthracis has been identified as a potential military and bioterror agent as it is relatively simple to produce, with spores that are highly resilient to degradation in the environment and easily dispersed. These characteristics are important in describing how anthrax could be used as a weapon, but they are also important in understanding and determining appropriate prevention and treatment of anthrax disease. Today, anthrax disease is primarily enzootic and found mostly in the developing world, where it is still associated with considerable mortality and morbidity in humans and livestock. This review article describes the spectrum of disease caused by anthrax and the various prevention and treatment options. Specifically we discuss the following; (1) clinical manifestations of anthrax disease (cutaneous, gastrointestinal, inhalational and intravenous-associated); (2) immunology of the disease; (3) an overview of animal models used in research; (4) the current World Health Organization and U.S. Government guidelines for investigation, management, and prophylaxis; (5) unique regulatory approaches to licensure and approval of anthrax medical countermeasures; (6) the history of vaccination and pre-exposure prophylaxis; (7) post-exposure prophylaxis and disease management; (8) treatment of symptomatic disease through the use of antibiotics and hyperimmune or monoclonal antibody-based antitoxin therapies; and (9) the current landscape of next-generation product candidates under development.

Current Status and Trends in Prophylaxis and Management of Anthrax Disease.

Correlation between anthrax lethal toxin neutralizing antibody levels and survival in guinea pigs and nonhuman primates vaccinated with the AV7909 anthrax vaccine candidate.

Vladimir Savransky

Papers

Pathology and Pathophysiology of Inhalational Anthrax in a Guinea Pig Model

Murine Lethal Toxic Shock Caused by Intranasal Administration of Staphylococcal Enterotoxin B

Current Status and Trends in Prophylaxis and Management of Anthrax Disease.

Correlation between anthrax lethal toxin neutralizing antibody levels and survival in guinea pigs and nonhuman primates vaccinated with the AV7909 anthrax vaccine candidate.

Toxicity of the staphylococcal enterotoxin B mutants with histidine-to-tyrosine substitutions.