Comparative Evaluation of the Effects of Agar and Biofilm Cultures of Francisella tularensis on the Immunological Reactivity of Experimental Animals.

We studied immunogenic properties of biofilm and agar cultures of Francisella tularensis strains. Analysis of the interaction of F. tularensis biofilm cultures with macrophages from experimental animals showed that the bacteria adapt to adverse conditions by forming biofilms, thereby increasing their virulence and subsequently suppressing the functional activity of immune cells. Biofilm formation in 7-day-old cultures of F. tularensis strains was associated with an increase in the virulent potential, which led to a decrease in the mean survival time and the overall survival rate of the experimental animals.