Identifying experimental surrogates for Bacillus anthracis spores: a review

Abstract

Bacillus anthracis, the causative agent of anthrax, is a proven biological weapon. In order to study this threat, a number of experimental surrogates have been used over the past 70 years. However, not all surrogates are appropriate for B. anthracis, especially when investigating transport, fate and survival. Although B. atrophaeus has been widely used as a B. anthracis surrogate, the two species do not always behave identically in transport and survival models. Therefore, we devised a scheme to identify a more appropriate surrogate for B. anthracis. Our selection criteria included risk of use (pathogenicity), phylogenetic relationship, morphology and comparative survivability when challenged with biocides. Although our knowledge of certain parameters remains incomplete, especially with regards to comparisons of spore longevity under natural conditions, we found that B. thuringiensis provided the best overall fit as a non-pathogenic surrogate for B. anthracis. Thus, we suggest focusing on this surrogate in future experiments of spore fate and transport modelling.

<i>Bacillus pumilus</i>: Possible Model for the Bioweapon <i>Bacillus anthracis</i>

“…To our knowledge, this is the first report of spore dimensions for B. pumilus. One criterion for an appropriate simulant for B. anthracis is spore size [14]. Carrera reported [11] that spores of B. anthracis fall into two size categories, a larger size of 1.49 -1.67 μm × 0.81 -0.86 μm and a smaller spore size of less than 1.26 μm × 0.81 -0.86 μm.…”

“…Bacillus pumilus has been phylogenetically placed within the branch for B. subtilis, an accepted simulant, based on the sequencing of 16S rDNA [13]. Several criteria have been suggested when considering an appropriate organism to model B. anthracis including virulence, genetic and morphologic similarity to B. anthracis, and how the simulant responds to challenges from chemicals or the environment [14]. Bacillus anthracis has been well-characterized and spore dimensions have been reported [11].…”

Urban Fate and Transport Modeling of Contaminants: The Unique Needs of Emergency Response and the Potential for Adapting Existing Models

“…CBR agents are likely unfamiliar to most practitioners in charge of city stormwater and watershed models, but a wealth of information is available in the peer reviewed literature (Bartelt-Hunt et al 2008;Garcia-Sanchez and Konoplev 2009;Greenberg et al 2010;Sinclair et al 2008). An introduction to biological (e.g.…”

Real-time qPCR Assay Development for Detection of Bacillus thuringiensis and Serratia marcescens DNA and the Influence of Complex Microbial Community DNA on Assay Sensitivity

“…Bacillus thuringiensis is a Gram-positive spore-forming bacterium that is found in a variety of environments (Schnepf et al 1998 anthracis with regard to physiology, spore formation, and overall similarity (Greenberg et al 2010;Justice 2010). …”

“…Ideally, organisms used as surrogates are nearly identical to the target organism in a variety of parameters such as morphology, genetic similarity, physiology, and environmental stimuli response (Greenberg et al 2010). Bacillus thuringiensis and Serratia marcescens have previously been used as surrogates for biological warfare agents B. anthracis and Y. pestis, respectively (Saikaly et al 2007;Greenberg et al 2010), and are used in my research.…”