Project description:Intrinsic and acquired defenses against bacteriophages, including Restriction/Modification, CRISPR/Cas, and Toxin/Anti-toxin systems have been intensely studied, with profound scientific impacts. However, adaptive defenses against phage infection analogous to adaptive resistance to antimicrobials have yet to be described. To identify such mechanisms, we applied an RNAseq-based, comparative transcriptomics approach in different \textit{Pseudomonas aeruginosa} strains after independent infection by a set of divergent virulent bacteriophages. A common host-mediated adaptive stress response to phages was identified that includes the Pseudomonas Quinolone Signal, through which infected cells inform their neighbors of infection, and what may be a resistance mechanism that functions by reducing infection vigor. With host transcriptional machinery left intact, we also observe phage-mediated differential expression caused by phage-specific stresses and molecular mechanisms. These responses suggest the presence of a conserved Bacterial Adaptive Phage Response mechanism as a novel type of host defense mechanism, and which may explain transient forms of phage persistence.
Project description:Comparisons of gnotobiotic Rag1-/- mice, with and without subcutaneous 260.8 hybridomas, disclosed that this IgA does not affect B. thetaiotaomicron population density or suppress 260.8 epitope production but does affect bacterial gene expression in ways that are emblematic of a diminished host innate immune response.
Project description:We illustrate an approach for integrating preclinical gnotobiotic animal models with human studies to understand the contributions of perturbed gut microbiota development to childhood undernutrition, and to identify new microbiota-directed therapeutic concepts/leads. Combining metabolomic and proteomic analyses of serially collected plasma samples with metagenomic analyses of serially collected fecal samples, we characterized the biological state of Bangladeshi children with severe acute malnutrition (SAM) as they transitioned to moderate acute malnutrition (MAM) after standard treatment. Gnotobiotic mice were subsequently colonized with a defined consortium of bacterial strains representing different stages of microbiota development in healthy children from Bangladesh. Administering different combinations of Bangladeshi complementary food ingredients to colonized mice and germ-free controls revealed diet-dependent changes in representation and metabolism of targeted weaning-phase strains, including accompanying increases in branched-chain amino acids, plus diet- and colonization-dependent augmentation of IGF-1/mTOR signaling. Host and microbial effects of microbiota-directed complementary food (MDCF) prototypes were subsequently examined in gnotobiotic mice colonized with post-SAM MAM microbiota and in gnotobiotic piglets colonized with a defined consortium of targeted age- and growth-discriminatory bacteria. Finally, ar andomized, double-blind study revealed a lead MDCF that affected the representation of targeted bacterial taxa and increased levels of biomarkers and mediators of growth, bone formation, neurodevelopment, and immune function.
Project description:Comparisons of gnotobiotic Rag1-/- mice, with and without subcutaneous 260.8 hybridomas, disclosed that this IgA does not affect B. thetaiotaomicron population density or suppress 260.8 epitope production but does affect bacterial gene expression in ways that are emblematic of a diminished host innate immune response. C57BL/6 wildtype, C57BL/6J Rag1-/- , and C57BL/6J Rag1-/- mice harboring the 260.8 IgA producing hybridoma were colonized for 10 days with Bacteroides thetaiotaomicron VPI-5482.
Project description:Purpose: We investigated the host immune response and the virus evasion mechanism in gnotobiotic pig infected with HuNoV by mRNA sequencing.
Project description:We compare the transcriptome of gnotobiotic Ae. aegypti generated by contaminating axenic (bacteria-free) larvae with bacterial isolates found in natural mosquito breeding sites. We focused on four bacterial isolates (Lysobacter, Flavobacterium, Paenibacillus and Enterobacteriaceae) and found that different gnotobiotic treatments resulted in massive transcriptomic changes throughout the mosquito development.
Project description:In this study, the minimal consortium Oligo-Mouse Microbiota (OMM)12 was used to study the function of Coriobacteriia under defined conditions in gnotobiotic mice. OMM12 mice with or without adding the dominant gut bacterium Eggerthella lenta were fed with diets varying in fat content or supplemented with primary bile acids. Changes in the host liver proteomes were studied using untargeted proteomics.
Project description:The interrelationships between our diets and the structure and operations of our gut microbial communities are poorly understood. A model microbial community of ten sequenced human gut bacteria was introduced into gnotobiotic mice and changes in the abundance of each species were measured in response to randomized perturbations of four defined ingredients in the host diet. From the responses, we developed a statistical model that predicted over 50% of the variation in species abundance in response to the diet perturbations and were able to identify which factors in the diet best explained the changes seen for each community member. The community’s transcriptional response was driven by the absolute abundance of each species, as diet ingredient concentrations were not associated with significant changes in the transcription of individual community members.
Project description:We analyze differential gene expression of Salmonella Tm M2702 and E. coli Mt1B1 in mice colonized with two different gnotobiotic consortia
Project description:Lactobacillus rhamnosus GG (LGG) is the most widely used probiotic, but the mechanisms underlying its beneficial effects remain unresolved. Previous studies typically inoculated LGG in hosts with established gut microbiota, limiting the understanding of specific impacts of LGG on host due to numerous interactions among LGG, commensal microbes, and the host. There has been a scarcity of studies that used gnotobiotic animals to elucidate LGG-host interaction, in particular for gaining specific insights about how it modifies metabolome. To evaluate whether LGG affects the metabolite output of pathobionts, we inoculated LGG into gnotobiotic mice along with a gut-disruptive consortium containing Propionibacterium acnes, Turicibacter sanguinis, and Staphylococcus aureus (PTS).
