Inhalation Anthrax (Ames aerosol) in Naive and Vaccinated New Zealand Rabbits: Characterizing the Spread of Bacteria from Lung Deposition to Bacteremia
NAVAL SURFACE WARFARE CENTER DAHLGREN DIV VA
Pagination or Media Count:
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 LD50 of Bacillus anthracis Ames spores immediately following exposure through 36 h. The primary goal of collecting the data was to support investigators in developing computational models of inhalational anthrax disease. Rabbits were vaccinated prior to exposure with the human vaccine Anthrax Vaccine Adsorbed, AVA or were sham-vaccinated, and were then exposed in pairs one sham and one AVA so disease kinetics could be characterized in equally-dosed hosts where one group is fully protected and is able to clear the infection AVA-vaccinated, while the other is susceptible to disease, in which case the bacteria are able to escape containment and replicate uncontrolled sham-vaccinated rabbits. Between 4-5 of the presented aerosol dose was retained in the lung of sham- and AVA-vaccinated rabbits as measured by dilution plate analysis of homogenized lung tissue or bronchoalveolar lavage BAL fluid. After 6 and 36 h, 80 and 96, respectively, of the deposited spores were no longer detected in BAL, with no detectable difference between sham- or AVA-vaccinated rabbits. Thereafter, differences between the two groups became noticeable. In sham-vaccinated rabbits the bacteria were detected in the tracheobronchial lymph nodes TBLN 12 h post-exposure and in the circulation at 24 h, a time point which was also associated with dramatic increases in vegetative CFU in the lung tissue of some animals. In all sham-vaccinated rabbits, bacteria increased in both TBLN and blood through 36 h at which point in time some rabbits succumbed to disease.
- Animal Husbandry and Veterinary Medicine
- Medicine and Medical Research