Effect of agar and biofilm culture of Francisella tularensis on TLR2 and TLR4 genes expression in blood and spleen cells of experimental animals

Biofilm as a form of existence of many bacteria that allows them to survive in unfavorable environmental conditions. Such pathogens include some strains of tularemia pathogen. Immunogenic properties of Francisella tularensis strains capable of biofilm formation are insufficiently studied. One of the key indicators of the activation of innate immunity is an increase in the level of TLRs expression. A comparative analysis of TLRs gene expression in immunocompetent cells of animals infected with biofilm and agar cultures will allow us to assess the degree of their adaptive capacity to the pathogen, as well as add to the existing data on the pathogenesis of tularemia.
The aim. To evaluate the effect of biofilm and agar cultures of F. tularensis on the expression of TLRs genes of types 2 and 4 by blood and spleen cells of white mice.
Materials and methods. The study was carried out on 125 certified mongrel white mice. Material (blood and spleen) was collected on days 1, 2, 3, 7 and 14. Seven-dayold biofilm and two-day-old agar cultures of attenuated vaccine strain F. tularensis 15B of the NIIEG line and avirulent F. tularensis I-384 were used to create experimental tularemia infection. RNA molecule detection and reverse transcription were performed using commercial reagent kits. TLR2 and TLR4 cDNA concentration was determined by real-time PCR using specific primers.
Comparative analysis of TLR2 and TLR4 gene expression in response to the introduction of biofilm and agar cultures of F. tularensis revealed a statistically significant increase in TLRs gene expression in cells of experimental animals infected with biofilm cultures compared to agar cultures.
Conclusion. The obtained results indicate a significant effect of F. tularensis subspecies and conditions of its cultivation on TLR2 and TLR4 genes expression in blood and spleen cells of white mice in experimental tularemia.

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