Evaluation of two methods for detection of viable Bacillus anthracis simulant spores in maritime environmental samples.

Analytical methods exist to detect biothreat agents in environmental samples during a response to biological contamination incidents. However, the coastal zone facilities and assets of the US Coast Guard (USCG), including response boats in diverse geographical areas and maritime environmental conditions, can pose complex and unique challenges for adapting existing analytical detection methods. The traditional culture (TC) and the rapid viability polymerase chain reaction (RV-PCR) methods were evaluated for their compatibility for maritime environmental surface and grab sample analysis to detect spores of Bacillus thuringiensis subspecies kurstaki (Btk), a surrogate for Bacillus anthracis.

Physiological Responses to Multiple Low-Doses of Spores in the Rabbit Model of Inhalation Anthrax.

spores that are re-aerosolized from surface deposits after initial contamination present significant health risks for personnel involved in decontamination. To model repeated exposure to low dose spores, three groups of seven rabbits were challenged with multiple low-doses of spores 5 days a week for 3 weeks. Mortality, body temperature, heart and respiration rates, hematology, C-reactive protein, bacteremia, and serum protective antigen were monitored for 21 days post-exposure after the last of multiple doses.

Comparison of surface sampling methods for an extended duration outdoor biological contamination study.

Bacillus anthracis, the causative agent for anthrax, is a dangerous pathogen to humans and has a history as a bioterrorism agent. While sampling methods have been developed and evaluated for characterizing and clearing contaminated indoor sites, the performance of these sampling methods is unknown for use in outdoor environments. This paper presents surface sampling data for Bacillus atrophaeus spores, a surrogate for B.

Physiological Responses to a Single Low-Dose of Spores in the Rabbit Model of Inhalational Anthrax.

Credible dose-response relationships are needed to more accurately assess the risk posed by exposure to low-level contamination during or following a release. To begin to fill this knowledge gap, New Zealand White rabbits were implanted with D70-PCT telemetry transmitters and subsequently aerosol challenged with average inhaled doses of 2.86 x 10 to 2.

Modeling Rabbit Responses to Single and Multiple Aerosol Exposures of Bacillus anthracis Spores.

Survival models are developed to predict response and time-to-response for mortality in rabbits following exposures to single or multiple aerosol doses of Bacillus anthracis spores. Hazard function models were developed for a multiple-dose data set to predict the probability of death through specifying functions of dose response and the time between exposure and the time-to-death (TTD). Among the models developed, the best-fitting survival model (baseline model) is an exponential dose-response model with a Weibull TTD distribution.

Considerations for estimating microbial environmental data concentrations collected from a field setting.

In the event of an indoor release of an environmentally persistent microbial pathogen such as Bacillus anthracis, the potential for human exposure will be considered when remedial decisions are made. Microbial site characterization and clearance sampling data collected in the field might be used to estimate exposure. However, there are many challenges associated with estimating environmental concentrations of B.

Assessment of relative potential for Legionella species or surrogates inhalation exposure from common water uses.

The Legionella species have been identified as important waterborne pathogens in terms of disease morbidity and mortality. Microbial exposure assessment is a tool that can be utilized to assess the potential of Legionella species inhalation exposure from common water uses. The screening-level exposure assessment presented in this paper developed emission factors to model aerosolization, quantitatively assessed inhalation exposures of aerosolized Legionella species or Legionella species surrogates while evaluating two generalized levels of assumed water concentrations, and developed a relative ranking of six common in-home uses of water for potential Legionella species inhalation exposure.

Inhalational anthrax (Ames aerosol) in naïve and vaccinated New Zealand rabbits: characterizing the spread of bacteria from lung deposition to bacteremia.

There is a need to better understand inhalational anthrax in relevant animal models. This understanding could aid risk assessment, help define therapeutic windows, and provide a better understanding of disease. The aim here was to characterize and quantify bacterial deposition and dissemination in rabbits following exposure to single high aerosol dose (> 100 LD(50)) of Bacillus anthracis (Ames) spores immediately following exposure through 36 h.

Achieving consistent multiple daily low-dose Bacillus anthracis spore inhalation exposures in the rabbit model.

Repeated low-level exposures to biological agents could occur before or after the remediation of an environmental release. This is especially true for persistent agents such as B. anthracis spores, the causative agent of anthrax.

Benchmark dose analysis for Bacillus anthracis inhalation exposures in the nonhuman primate.

There is considerable variability in the published lethality values for inhalation exposures of Bacillus anthracis. The lack of consensus on an acceptable dose-response relationship poses a significant challenge in the development of risk-based management approaches for use following a terrorist release of B. anthracis spores.

Toxicity of anthrax toxin is influenced by receptor expression.

Anthrax toxin protective antigen (PA) binds to its cellular receptor, and seven subunits self-associate to form a heptameric ring that mediates the cytoplasmic entry of lethal factor or edema factor. The influence of receptor type on susceptibility to anthrax toxin components was examined using Chinese hamster ovary (CHO) cells expressing the human form of one of two PA receptors: TEM8 or CMG2. Unexpectedly, PA alone, previously believed to only mediate entry of lethal factor or edema factor, was found to be toxic to CHO-TEM8 cells; cells treated with PA alone displayed reduced cell growth and decreased metabolic activity.

Neutralizing activity of vaccine-induced antibodies to two Bacillus anthracis toxin components, lethal factor and edema factor.

Anthrax vaccine adsorbed (AVA; BioThrax), the current FDA-licensed human anthrax vaccine, contains various amounts of the three anthrax toxin components, protective antigen (PA), lethal factor (LF), and edema factor (EF). While antibody to PA is sufficient to mediate protection against anthrax in animal models, it is not known if antibodies to LF or EF contribute to protection in humans. Toxin-neutralizing activity was evaluated in sera from AVA-vaccinated volunteers, all of whom had antibody responses to LF and EF, as well as PA.

Neutralizing antibodies and persistence of immunity following anthrax vaccination.

Anthrax toxin consists of protective antigen (PA) and two toxic components, lethal factor (LF) and edema factor (EF). PA binds to mammalian cellular receptors and delivers the toxic components to the cytoplasm. PA is the primary antigenic component of the current anthrax vaccine.

Distribution of borreliae among ticks collected from eastern states.

Lyme disease is the most commonly reported vector-borne disease in the United States and is transmitted by Borrelia burgdorferi-infected Ixodes species. The disease is typically characterized by an erythema migrans (EM) rash at the site of tick feeding. EM rashes have also been associated with feeding by Amblyomma americanum ticks despite evidence suggesting that they are incompetent vectors for Lyme disease.