Search

BackgroundBoth the gut microbiota and chronic viral infections have profound effects on host immunity, but interactions between these influences have been only superficially explored. Cytomegalovirus (CMV), for example, infects approximately 80% of people globally and drives significant changes in immune cells. Similarly, certain gut-resident bacteria affect T-cell development in mice and nonhuman primates. It is unknown if changes imposed by CMV on the intestinal microbiome contribute to immunologic effects of the infection.ResultsWe show that rhesus cytomegalovirus (RhCMV) infection is associated with specific differences in gut microbiota composition, including decreased abundance of Firmicutes, and that the extent of microbial change was associated with immunologic changes including the proliferation, differentiation, and cytokine production of CD8+ T cells. Furthermore, RhCMV infection disrupted the relationship between short-chain fatty acid producers and Treg/Th17 balance observed in seronegative animals, showing that some immunologic effects of CMV are due to disruption of previously existing host-microbe relationships.ConclusionsGut microbes have an important influence on health and disease. Diet is known to shape the microbiota, but the influence of concomitant chronic viral infections is unclear. We found that CMV influences gut microbiota composition to an extent that is correlated with immunologic changes in the host. Additionally, pre-existing correlations between immunophenotypes and gut microbes can be subverted by CMV infection. Immunologic effects of CMV infection on the host may therefore be mediated by two different mechanisms involving gut microbiota. Video Abstract.

The development of biopolymer scaffolds for intestine regeneration is one of the most actively developing areas in tissue engineering. However, intestinal regenerative processes after scaffold implantation depend on the activity of the intestinal microbial community that is in close symbiosis with intestinal epithelial cells. In this work, we study the impact of different scaffolds based on biocompatible poly(3-hydroxybutyrate) (PHB) and alginate (ALG) as well as PHB/ALG scaffolds seeded with probiotic bacteria on the composition of gut microbiota of Wistar rats. Implantation of PHB/ALG scaffolds on the large-intestine wall to close its injury showed that alpha diversity of the gut microbiota was not reduced in rats implanted with different PHB/ALG scaffolds except for the PHB/ALG scaffolds with the inclusion of Lactobacillus spheres (PHB/ALG-L). The composition of the gut microbiota of rats implanted with PHB/ALG scaffolds with probiotic bacteria or in simultaneous use of an antimicrobial agent (PHB/ALG-AB) differed significantly from other experimental groups. All rats with implanted scaffolds demonstrated shifts in the composition of the gut microbiota by individual operational taxonomic units. The PHB/ALG-AB construct led to increased abundance of butyrate-producing bacteria: Ileibacterium sp. dominated in rats with implanted PHB/ALG-L and Lactobacillus sp. and Bifidobacterium sp. dominated in the control group. In addition, the PHB/ALG scaffolds had a favourable effect on the growth of commensal bacteria. Thus, the effect of implantation of the PHB/ALG scaffold compared to other scaffolds on the composition of the gut microbiota was closest to the control variant, which may demonstrate the biocompatibility of this device with the microbiota. [ABSTRACT FROM AUTHOR]

Abstract Background Spore-forming bacteria of the Bacillus genus are widely used probiotics known to exert their beneficial effects also through the stimulation of the host immune response. The oral delivery of B. toyonensis spores has been shown to improve the immune response to a parenterally administered viral antigen in mice, suggesting that probiotics may increase the efficiency of systemic vaccines. We used the C fragment of the tetanus toxin (TTFC) as a model antigen to evaluate whether a treatment with B. toyonensis spores affected the immune response to a mucosal antigen. Results Purified TTFC was given to mice by the nasal route either as a free protein or adsorbed to B. subtilis spores, a mucosal vaccine delivery system proved effective with several antigens, including TTFC. Spore adsorption was extremely efficient and TTFC was shown to be exposed on the spore surface. Spore-adsorbed TTFC was more efficient than the free antigen in inducing an immune response and the probiotic treatment improved the response, increasing the production of TTFC-specific secretory immunoglobin A (sIgA) and causing a faster production of serum IgG. The analysis of the induced cytokines indicated that also the cellular immune response was increased by the probiotic treatment. A 16S RNA-based analysis of the gut microbial composition did not show dramatic differences due to the probiotic treatment. However, the abundance of members of the Ruminiclostridium 6 genus was found to correlate with the increased immune response of animals immunized with the spore-adsorbed antigen and treated with the probiotic. Conclusion Our results indicate that B. toyonensis spores significantly contribute to the humoral and cellular responses elicited by a mucosal immunization with spore-adsorbed TTFC, pointing to the probiotic treatment as an alternative to the use of adjuvants for mucosal vaccinations.

Background: Spore-forming bacteria of the Bacillus genus are widely used probiotics known to exert their beneficial effects also through the stimulation of the host immune response. The oral delivery of B. toyonensis spores has been shown to improve the immune response to a parenterally administered viral antigen in mice, suggesting that probiotics may increase the efficiency of systemic vaccines. We used the C fragment of the tetanus toxin (TTFC) as a model antigen to evaluate whether a treatment with B. toyonensis spores affected the immune response to a mucosal antigen. Results: Purified TTFC was given to mice by the nasal route either as a free protein or adsorbed to B. subtilis spores, a mucosal vaccine delivery system proved effective with several antigens, including TTFC. Spore adsorption was extremely efficient and TTFC was shown to be exposed on the spore surface. Spore-adsorbed TTFC was more efficient than the free antigen in inducing an immune response and the probiotic treatment improved the response, increasing the production of TTFC-specific secretory immunoglobin A (sIgA) and causing a faster production of serum IgG. The analysis of the induced cytokines indicated that also the cellular immune response was increased by the probiotic treatment. A 16S RNA-based analysis of the gut microbial composition did not show dramatic differences due to the probiotic treatment. However, the abundance of members of the Ruminiclostridium 6 genus was found to correlate with the increased immune response of animals immunized with the spore-adsorbed antigen and treated with the probiotic. Conclusion: Our results indicate that B. toyonensis spores significantly contribute to the humoral and cellular responses elicited by a mucosal immunization with spore-adsorbed TTFC, pointing to the probiotic treatment as an alternative to the use of adjuvants for mucosal vaccinations. [ABSTRACT FROM AUTHOR]

Botryococcus braunii CCALA778 is a green microalga that can produce large amounts of extracellular carbohydrates and therefore is a potential host for industrial applications such as materials, food and pharmaceutical products. The downside of B. braunii is its slow growth and therefore, improvements on the biomass productivity or carbohydrate production will make this microalga more attractive for industrial exploitation. Microalgae grow naturally in the presence of bacteria and these can be beneficial or antagonistic. In outdoor cultivation systems, contamination by bacteria is common. The role or effects of bacteria present in B. braunii CCALA778 are not yet fully elucidated. We used UV-C treatment to reduce bacterial abundance in B. braunii CCALA778 cultures and 16S rRNA gene amplicon MiSeq sequencing for bacterial community analysis. The effect of the reduced amount of bacteria on biomass growth and production of extracellular carbohydrates was analysed. It is shown that UV-C treatment can reduce the bacterial population substantially without harming B. braunii. Bacteria removed by UV-C were antagonistic to B. braunii CCALA778 as in their absence production of biomass and extracellular carbohydrates was enhanced significantly. CCALA778 treated with UV-C accumulated 826 ± 61 mg L−1 of extracellular carbohydrates by day 15 compared with 422 ± 135 mg L−1 accumulated extracellular carbohydrates in the untreated culture. [ABSTRACT FROM AUTHOR]

Methane is a very potent greenhouse gas and can be oxidized aerobically or anaerobically through microbe-mediated processes, thus decreasing methane emissions in the atmosphere. Using a complementary array of methods, including phylogenetic analysis, physiological experiments, and light and electron microscopy techniques (including electron tomography), we investigated the community composition and ultrastructure of a continuous bioreactor enrichment culture, in which anaerobic oxidation of methane (AOM) was coupled to nitrate reduction. A membrane bioreactor was seeded with AOM biomass and continuously fed with excess methane. After 150 days, the bioreactor reached a daily consumption of 10 mmol nitrate · liter-1 · day-1. The biomass consisted of aggregates that were dominated by nitratedependent anaerobic methane-oxidizing "Candidatus Methanoperedens"-like archaea (40%) and nitrite-dependent anaerobic methane-oxidizing "Candidatus Methylomirabilis"-like bacteria (50%). The "Ca. Methanoperedens" spp. were identified by fluorescence in situ hybridization and immunogold localization of the methyl-coenzyme M reductase (Mcr) enzyme, which was located in the cytoplasm. The "Ca. Methanoperedens" sp. aggregates consisted of slightly irregular coccoid cells (-1.5-μm diameter) which produced extruding tubular structures and putative cell-to-cell contacts among each other. "Ca. Methylomirabilis" sp. bacteria exhibited the polygonal cell shape typical of this genus. In AOM archaea and bacteria, cytochrome c proteins were localized in the cytoplasm and periplasm, respectively, by cytochrome staining. Our results indicate that AOM bacteria and archaea might work closely together in the process of anaerobic methane oxidation, as the bacteria depend on the archaea for nitrite. Future studies will be aimed at elucidating the function of the cell-to-cell interactions in nitrate-dependent AOM. [ABSTRACT FROM AUTHOR]

Combined fecal microbiota transfer and antibiotic treatment prevented recurrences of urinary tract infections with multidrug-resistant (MDR) Pseudomonas aeruginosa, but it failed to eradicate intestinal colonization with MDR Escherichia coli. Based on microbiota analysis, failure was not associated with distinct diminished microbiota diversity. [ABSTRACT FROM AUTHOR]