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Characterization of Bacillus anthracis persistence in vivo.

Jenkins SA, Xu Y - PLoS ONE (2013)

Bottom Line: Immunofluorescence staining of lung sections showed that spores associated with the alveolar and airway epithelium.We also showed that the anthrax toxins did not play a role in persistence.Together, the results suggest that B. anthracis spores have special properties that promote their persistence in the lung, and that there may be multiple mechanisms contributing to spore persistence.

View Article: PubMed Central - PubMed

Affiliation: Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas, USA.

ABSTRACT
Pulmonary exposure to Bacillus anthracis spores initiates inhalational anthrax, a life-threatening infection. It is known that dormant spores can be recovered from the lungs of infected animals months after the initial spore exposure. Consequently, a 60-day course antibiotic treatment is recommended for exposed individuals. However, there has been little information regarding details or mechanisms of spore persistence in vivo. In this study, we investigated spore persistence in a mouse model. The results indicated that weeks after intranasal inoculation with B. anthracis spores, substantial amounts of spores could be recovered from the mouse lung. Moreover, spores of B. anthracis were significantly better at persisting in the lung than spores of a non-pathogenic Bacillus subtilis strain. The majority of B. anthracis spores in the lung were tightly associated with the lung tissue, as they could not be readily removed by lavage. Immunofluorescence staining of lung sections showed that spores associated with the alveolar and airway epithelium. Confocal analysis indicated that some of the spores were inside epithelial cells. This was further confirmed by differential immunofluorescence staining of lung cells harvested from the infected lungs, suggesting that association with lung epithelial cells may provide an advantage to spore persistence in the lung. There was no or very mild inflammation in the infected lungs. Furthermore, spores were present in the lung tissue as single spores rather than in clusters. We also showed that the anthrax toxins did not play a role in persistence. Together, the results suggest that B. anthracis spores have special properties that promote their persistence in the lung, and that there may be multiple mechanisms contributing to spore persistence.

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H&E stained lung sections of mice challenged with B. anthracis spores.Lungs from infected and control mice were collected at 2, 4, and 8 weeks post-inoculation, fixed and subjected to H&E staining. Representative images displaying the alveoli and the airway from mice infected for 2 (A–C), 4 (D–F), and 8 weeks (G–I), and uninfected control mice (J–L) are shown. Scale bars represent 20 µm.
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pone-0066177-g005: H&E stained lung sections of mice challenged with B. anthracis spores.Lungs from infected and control mice were collected at 2, 4, and 8 weeks post-inoculation, fixed and subjected to H&E staining. Representative images displaying the alveoli and the airway from mice infected for 2 (A–C), 4 (D–F), and 8 weeks (G–I), and uninfected control mice (J–L) are shown. Scale bars represent 20 µm.

Mentions: We further analyzed lung sections from infected mice to determine the location of spores in the lung. Lung sections were obtained from mice infected with B. anthracis spores at 2, 4, and 8 weeks. Hematoxylin and eosin (H&E) staining of the sections showed minimal pathology in the lung (Fig. 5). The alveolar and small airway epithelium as well as blood vessels appeared intact. For most part of the lung, we observed no signs of inflammation (Fig. 5, A, B, D, E, G and H). We occasionally observed isolated foci that had inflammatory infiltrates at both 2 and 4 weeks (Fig. 5, C and F). At 8 weeks, the lungs were indistinguishable from the uninfected lung (Fig. 5, G–L).


Characterization of Bacillus anthracis persistence in vivo.

Jenkins SA, Xu Y - PLoS ONE (2013)

H&E stained lung sections of mice challenged with B. anthracis spores.Lungs from infected and control mice were collected at 2, 4, and 8 weeks post-inoculation, fixed and subjected to H&E staining. Representative images displaying the alveoli and the airway from mice infected for 2 (A–C), 4 (D–F), and 8 weeks (G–I), and uninfected control mice (J–L) are shown. Scale bars represent 20 µm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3672131&req=5

pone-0066177-g005: H&E stained lung sections of mice challenged with B. anthracis spores.Lungs from infected and control mice were collected at 2, 4, and 8 weeks post-inoculation, fixed and subjected to H&E staining. Representative images displaying the alveoli and the airway from mice infected for 2 (A–C), 4 (D–F), and 8 weeks (G–I), and uninfected control mice (J–L) are shown. Scale bars represent 20 µm.
Mentions: We further analyzed lung sections from infected mice to determine the location of spores in the lung. Lung sections were obtained from mice infected with B. anthracis spores at 2, 4, and 8 weeks. Hematoxylin and eosin (H&E) staining of the sections showed minimal pathology in the lung (Fig. 5). The alveolar and small airway epithelium as well as blood vessels appeared intact. For most part of the lung, we observed no signs of inflammation (Fig. 5, A, B, D, E, G and H). We occasionally observed isolated foci that had inflammatory infiltrates at both 2 and 4 weeks (Fig. 5, C and F). At 8 weeks, the lungs were indistinguishable from the uninfected lung (Fig. 5, G–L).

Bottom Line: Immunofluorescence staining of lung sections showed that spores associated with the alveolar and airway epithelium.We also showed that the anthrax toxins did not play a role in persistence.Together, the results suggest that B. anthracis spores have special properties that promote their persistence in the lung, and that there may be multiple mechanisms contributing to spore persistence.

View Article: PubMed Central - PubMed

Affiliation: Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas, USA.

ABSTRACT
Pulmonary exposure to Bacillus anthracis spores initiates inhalational anthrax, a life-threatening infection. It is known that dormant spores can be recovered from the lungs of infected animals months after the initial spore exposure. Consequently, a 60-day course antibiotic treatment is recommended for exposed individuals. However, there has been little information regarding details or mechanisms of spore persistence in vivo. In this study, we investigated spore persistence in a mouse model. The results indicated that weeks after intranasal inoculation with B. anthracis spores, substantial amounts of spores could be recovered from the mouse lung. Moreover, spores of B. anthracis were significantly better at persisting in the lung than spores of a non-pathogenic Bacillus subtilis strain. The majority of B. anthracis spores in the lung were tightly associated with the lung tissue, as they could not be readily removed by lavage. Immunofluorescence staining of lung sections showed that spores associated with the alveolar and airway epithelium. Confocal analysis indicated that some of the spores were inside epithelial cells. This was further confirmed by differential immunofluorescence staining of lung cells harvested from the infected lungs, suggesting that association with lung epithelial cells may provide an advantage to spore persistence in the lung. There was no or very mild inflammation in the infected lungs. Furthermore, spores were present in the lung tissue as single spores rather than in clusters. We also showed that the anthrax toxins did not play a role in persistence. Together, the results suggest that B. anthracis spores have special properties that promote their persistence in the lung, and that there may be multiple mechanisms contributing to spore persistence.

Show MeSH
Related in: MedlinePlus