Genome Features of Probiotic Bifidobacteria Determining Their Strain-Specific Properties.

The aim of the study was to analyze the genome features of the probiotic strains Bifidobacterium longum 379, Bifidobacterium bifidum 1, and Bifidobacterium bifidum 791 and study their antiviral activity. Materials and Methods: Whole genome sequencing of three strains of bifidobacteria was performed on the MiSeq platform (Illumina Inc., USA). The genomes were annotated using the Prokka v. 1.11 utility and RAST genomic server. The individual genetic determinants were searched using the ResFinder 3.2, PathogenFinder, PlasmidFinder, RAST, and Bagel 4 software. The antiviral activity of the strains against influenza A viruses was studied using MDCK cells (Madin-Darby canine kidney cells), the epidemic strain of influenza A/Lipetsk/1V/2018 (H1N1 pdm09) (EPI_ISL_332798), the highly pathogenic avian influenza virus A/common gull/Saratov/1676/2018 (H5N6) strain (EPI_ISL_336925), and neutral red vital dye. Results: The genomes of all studied strains contained determinants responsible for utilization of carbohydrates of plant origin; the genes of key enzymes for the synthesis of tryptophan and folic acid are present in the genomes of B. longum 379 and B. bifidum 791. A feature of the B. bifidum 791 genome is the presence of determinants responsible for the synthesis of thermostable type I bacteriocins - flavucin and lasso peptide. The B. bifidum 791 strain was found to show pronounced antiviral activity against both the strains of influenza A, the supernatant of which suppressed viral replication in vitro up to a dilution of 1:8, and the cells inhibited viral reproduction up to a concentration of 6·106 CFU/ml. Conclusion: The analysis of complete genomes of B. longum 379, B. bifidum 1, and B. bifidum 791 showed features that determine their strain-specific properties, the findings on which were previously made empirically based on indirect signs. In the genomes of B. longum 379 and B. bifidum 791 strains, in contrast to B. bifidum 1 strain, key enzymes for the synthesis of tryptophan and folic acid were found. These substances have an impact on the human body in many ways, including having a thymoleptic effect (reducing emotional stress, irritability, anxiety, eliminating lethargy, apathy, melancholy, anxiety) and regulating cognitive activity. The presence of determinants responsible for the synthesis of thermostable type I bacteriocins in the genome of B. bifidum 791 strain determines its pronounced antiviral activity.

[ANALYSIS OF POPULATION IMMUNITYAGAINST INFLUENZA PRIOR TO 2014 AND 2015 EPIDEMIC SEASONS].

AIM: Control for the population herd immunity against seasonal influenza viruses as well as for emergence of antibodies against influenza with pandemic potential in human blood sera. MATERIALS AND METHODS: HAI reaction against vaccine and epidemic influenza viruses as well as HPAI viruses A/rook/Chany/32/2015 (H5N1) (clade 2.3.2. lc.) andA/Anhui/01/2013 (H7N9). RESULTS: Among all the sera samples collected in the autumn of 2014 and 2015, none had reacted in HAI against A(H5N 1) and A(H7N9) antigens even at 1:10 dilution. Among samples collected in autumn 2014, 41% were positive to A/California/07/09(H1Nlpdm9) virus, 36% - A/Texas/50/2012 (H3N2), 40% - B/Brisbane/60/2008 (Vict.lin.) and 47% reacted in HAI against the B/Massachusetts/2/2012 (Yam.lin.) strain. 22% of all the samples had a titer of at least 40 against all the antigens and only 10% in HAI had a titer of 40 or more against all the vaccine strains. Among the samples collected in autumn 2015, the number of seropositive against A/California/07/09(HlNlpdmO9) varied from 31% in the Urals FD to 46% in the Southern FD. The amount of seropositive against A/Switzerland/9715293/13 (H3N2) strain was at the level of 4 - 13% in all the FDs except Urals, where this parameter was slightly above 30%. The amount of seropositive against vaccine influenza B viruses varied from 23 to 76%. Only 2% of sera had titers in HAI of 40 or above against all the vaccine strains, 29% of all the samples were seronegative. CONCLUSION: Population immunity in Russia against influenza A(H3N2) is at a very low level, thus socially significant consequences of influenza epidemics in many aspects will depend on the vaccination campaign of autumn 2016.

Inactivation and mineralization of aerosol deposited model pathogenic microorganisms over TiO2 and Pt/TiO2.

Air disinfection from bacteria and viruses by means of photocatalytic oxidation is investigated with microorganisms loaded over photocatalysts' films from aerosols. Deposition method and equipment have been developed to load Mycobacterium smegmatis , Bacillus thuringiensis , vaccinia virus, and influenza A (H3N2) virus on slides with undoped TiO(2) and platinized sulfated TiO(2) (Pt/TiO(2)). Inactivation dynamics was measured under UVA irradiation and in the dark. About 90% inactivation is reached in 30 min irradiation on TiO(2) and from 90 to 99.8% on Pt/TiO(2). The first-order inactivation rate coefficient ranged from 0.18 to 0.03 min(-1), over Pt/TiO(2) being higher than on TiO(2) for all microorganisms except Bacillus thuringiensis. The photocatalytic mineralization of Bacillus thuringiensis was performed on TiO(2) and Pt/TiO(2) with different photocatalyst and microorganism loadings. Completeness of mineralization depended on the TiO(2) to bacteria mass ratio. The rate of the photocatalytic carbon dioxide production grows with both the cell mass increase and the photocatalyst mass increase. Pt/TiO(2) showed increased rate of mineralization as well as of the inactivation likely due to a better charge carrier separation in the doped semiconductor photocatalyst. The results demonstrate that photocatalytic filters with deposited TiO(2) or Pt/TiO(2) are able to inactivate aerosol microorganisms and completely decompose them into inorganic products and Pt/TiO(2) provides higher disinfection and mineralization rates.

[Experimental evaluation of the protective properties of some nonwoven materials for respiratory protection means and prospects of their use].

The protective properties of nonwoven materials (Spandbond, SMS) used to manufacture 3-5-layer medical masks, by using model physical and bacterial test aerosols, were experimentally assessed. It was shown that the more layers of the materials, the less permeable they became for test aerosols. Three-five-layer masks made from SMS at a density of 42 g/m2 were found to have higher protective properties for oil mist and fine aerosol than those made from Spandbond at a density of 25 g/m2. Five-layer SMS materials at a density of 42 g/m2 have the highest values of bacterial aerosol retention.