Evaluation of the Effectiveness of Metabolites of Bacterial Strains Bacillus thuringiensis against Human Influenza Virus A/Aichi/2/68 (H3N2) In Vitro and In Vivo

The morphological and physiological characteristics of Bacillus thuringiensis strains were analyzed and conditions for obtaining culture fluid with maximum yield of secreted RNases were determined. Zymographic analysis showed that culture fluid of B. thuringiensis strains along with low-molecular-weight (15-20 kDa) RNases contained enzymes with a molecular weight ~55 kDa and their content depended on the duration and conditions of culturing. Preparations based on B. thuringiensis culture fluid were effective against human influenza virus A/Aichi/2/68 (H3N2). In experiments on mice infected with 10 LD50 influenza virus strain A/Aichi/2/68 (H3N2), we selected effective variants of preparations based on culture fluid of B. thuringiensi strains for preventive administration that provided reliable protection of infected animals (protection coefficient 50%), close to that of the reference drug Tamiflu.