Anthrax vaccine efficacy in golden Syrian hamsters

The efficacy of a licensed human anthrax vaccine (anthrax vaccine adsorbed, AVA) was tested in golden Syrian hamsters against a virulent Bacillus anthracis spore challenge. Groups of golden Syrian hamsters were vaccinated at either 0 and 4 weeks or 0, 4 and 8 weeks, then challenged subcutaneously (s.c.) at 10 weeks with spores of various B. anthracis isolates. Although ELISA and toxin neutralization assays demonstrated high titers, none of the AVA-vaccinated hamsters were protected from challenge or demonstrated a significantly extended time to death compared to that of control animals. The results of the study demonstrate that the golden Syrian hamster is not an appropriate model for investigating human anthrax vaccine efficacy.