ABSTRACT: Genome-resolving metagenomics reveals wild western capercaillies (Tetrao urogallus) as avian hosts for antibiotic-resistance bacteria and their interactions with the gut-virome community
Project description:Campylobacter jejuni effectively promotes commensalism in the intestinal tract of avian hosts and diarrheal disease in humans, yet components of intestinal environments sensed by the bacterium in either host to initiate interactions are mostly unknown. By analyzing a C. jejuni acetogenesis mutant that is defective in both converting acetyl-CoA to acetate and commensal colonization of young chicks, we discovered evidence for C. jejuni sensing spatial gradients of microbiota-derived short-chain fatty acids (SCFAs) and organic acids to modulate expression of determinants required for commensalism. We identified in C. jejuni an SCFA-influenced regulon composed by genes encoding catabolic enzymes and transport systems for amino acids C. jejuni requires for in vivo growth. Expression of these genes was reduced in the acetogenesis mutant, but restored upon supplementation with physiological concentrations of SCFAs such as acetate and butyrate that are present in the lower intestinal tract of avian and human hosts. Conversely, the organic acid lactate, which is abundant in the upper intestinal tract of these hosts where C. jejuni less efficiently colonizes reduced expression of this regulon. We propose a model whereby C. jejuni senses microbiota-produced SCFAs and lactate for spatial orientation in the avian and human host. Sensing these metabolites likely allows C. jejuni to locate preferred niches in the lower intestinal tract and induce expression of factors required for in vivo growth. Our findings provide insights into the types of signals C. jejuni monitors in the avian host for commensalism and likely in the human host to promote diarrheal disease.
Project description:Toxoplasma gondii is a ubiquitous protozoan pathogen able to infect both mammalian and avian hosts. Surprisingly, just three strains appear to account for the majority of isolates from Europe and N. America. To test the hypothesis that strain divergence might be driven by differences between mammalian and avian response to infection, we examine in vitro strain-dependent host responses in a representative avian host, the chicken.
Project description:Toxoplasma gondii is a ubiquitous protozoan pathogen able to infect both mammalian and avian hosts. Surprisingly, just three strains appear to account for the majority of isolates from Europe and N. America. To test the hypothesis that strain divergence might be driven by differences between mammalian and avian response to infection, we examine in vitro strain-dependent host responses in a representative avian host, the chicken.
