title: Protective Yeasts ControlV. anguillarumPathogenicity and Modulate the Innate Immune Response of Challenged Zebrafish (Danio rerio) Larvae.
abstract: We investigated mechanisms involved in the protection of zebrafish (Danio rerio) larvae by two probiotic candidate yeasts,Debaryomyces hansenii97 (Dh97) andYarrowia lypolitica242 (Yl242), against aVibrio anguillarumchallenge. We determined the effect of different yeast concentrations (104-107CFU/mL) to: (i) protect larvae from the challenge, (ii) reduce thein vivopathogen concentration and (iii) modulate the innate immune response of the host. To evaluate the role of zebrafish microbiota in protection, the experiments were performed in conventionally raised and germ-free larvae.In vitroco-aggregation assays were performed to determine a direct yeast-pathogen interaction. Results showed that both yeasts significantly increased the survival rate of conventionally raised larvae challenged withV. anguillarum. The concentration of yeasts in larvae tended to increase with yeast inoculum, which was more pronounced for Dh97. Better protection was observed with Dh97 at a concentration of 106CFU/mL compared to 104CFU/mL. In germ-free conditionsV. anguillarumreached higher concentrations in larvae and provoked significantly more mortality than in conventional conditions, revealing the protective role of the host microbiota. Interestingly, yeasts were equally (Dh97) or more effective (Yl242) in protecting germ-free than conventionally-raised larvae, showing that protection can be exerted only by yeasts and is not necessarily related to modulation of the host microbiota. Although none of the yeasts co-aggregated withV. anguillarum, they were able to reduce its proliferation in conventionally raised larvae, reduce initial pathogen concentration in germ-free larvae and prevent the upregulation of key components of the inflammatory/anti-inflammatory response (il1b, tnfa, c3, mpx, andil10, respectively). These results show that protection by yeasts of zebrafish larvae challenged withV. anguillarumrelates to anin vivoanti-pathogen effect, the modulation of the innate immune system, and suggests that yeasts avoid the host-pathogen interaction through mechanisms independent of co-aggregation. This study shows, for the first time, the protective role of zebrafish microbiota againstV. anguillaruminfection, and reveals mechanisms involved in protection by two non-Saccharomycesyeasts against this pathogen.
authors: Laboratorio de Microbiología y Probióticos, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile Santiago, Chile.
authors: Mario
authors: M
authors: Caruffo
authors: Laboratorio de Microbiología y Probióticos, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile Santiago, Chile.
authors: Natalie C
authors: NC
authors: Navarrete
authors: Laboratorio de Microbiología y Probióticos, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile Santiago, Chile.
authors: Oscar A
authors: OA
authors: Salgado
authors: Laboratorio de Microbiología y Probióticos, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile Santiago, Chile.
authors: Nelly B
authors: NB
authors: Faúndez
authors: Laboratorio de Microbiología y Probióticos, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile Santiago, Chile.
authors: Miguel C
authors: MC
authors: Gajardo
authors: Departamento de Ciencias Biologicas, Facultad de Ciencias Biologicas, Universidad Andres Bello Santiago, Chile.
authors: Carmen G
authors: CG
authors: Feijóo
authors: Laboratorio de Microbiología y Probióticos, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile Santiago, Chile.
authors: Angélica
authors: A
authors: Reyes-Jara
authors: Instituto de Ciencias Biomédicas, Universidad Autónoma de Chile Santiago, Chile.
authors: Katherine
authors: K
authors: García
authors: Laboratorio de Microbiología y Probióticos, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile Santiago, Chile.
authors: Paola
authors: P
authors: Navarrete
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D007113:Immunity, Innate; D007155:Immunologic Factors / Q000008:administration & dosage*; D019936:Probiotics / Q000008:administration & dosage*; D004718:Saccharomycetales / Q000276:immunology*; D016019:Survival Analysis; D014735:Vibrio Infections / Q000276:immunology* / Q000473:pathology / Q000517:prevention & control; D015027:Zebrafish
chemical_list: D007155:Immunologic Factors
keywords: V. anguillarum; innate immune system; protective mechanisms; yeast probiotic; zebrafish