The Experts below are selected from a list of 195 Experts worldwide ranked by ideXlab platform

Jean-marc Ghigo - One of the best experts on this subject based on the ideXlab platform.

  • Gnotobiotic rainbow trout (Oncorhynchus mykiss) model reveals endogenous bacteria that protect against Flavobacterium columnare infection
    PLoS Pathogens, 2021
    Co-Authors: David Pérez-pascual, Sol Vendrell-fernández, Bianca Audrain, Joaquín Bernal-bayard, Rafael Patiño-navarrete, Vincent Petit, Dimitri Rigaudeau, Jean-marc Ghigo
    Abstract:

    The health and environmental risks associated with antibiotic use in aquaculture have promoted bacterial probiotics as an alternative approach to control fish infections in vulnerable larval and juvenile stages. However, evidence-based identification of probiotics is often hindered by the complexity of bacteria-host interactions and host variability in microbiologically uncontrolled conditions. While these difficulties can be partially resolved using gnotobiotic models harboring no or reduced microbiota, most host-microbe interaction studies are carried out in animal models with little relevance for fish farming. Here we studied host-microbiota-pathogen interactions in a germ-free and gnotobiotic model of rainbow trout (Oncorhynchus mykiss), one of the most widely cultured salmonids. We demonstrated that germ-free larvae raised in sterile conditions displayed no significant difference in growth after 35 days compared to conventionally-raised larvae, but were extremely sensitive to infection by Flavobacterium columnare, a common freshwater fish pathogen causing major economic losses worldwide. Furthermore, re-conventionalization with 11 culturable species from the conventional trout microbiota conferred resistance to F. columnare infection. Using mono-re-conventionalized germ-free trout, we identified that this protection is determined by a commensal Flavobacterium strain displaying antibacterial activity against F. columnare. Finally, we demonstrated that use of gnotobiotic trout is a suitable approach for the identification of both endogenous and exogenous probiotic bacterial strains protecting teleostean hosts against F. columnare. This study therefore establishes an ecologically-relevant gnotobiotic model for the study of host-pathogen interactions and colonization resistance in farmed fish.

  • gnotobiotic rainbow trout oncorhynchus mykiss model reveals endogenous bacteria that protect against flavobacterium columnare infection
    bioRxiv, 2020
    Co-Authors: David Perezpascual, Bianca Audrain, Vincent Petit, Dimitri Rigaudeau, Sol Vendrellfernandez, Joaquin Bernalbayard, Rafael Patinonavarrete, Jean-marc Ghigo
    Abstract:

    ABSTRACT The health and environmental risks associated with antibiotic use in aquaculture have promoted bacterial probiotics as an alternative approach to control fish infections in vulnerable larval and juvenile stages. However, evidence-based identification of probiotics is often hindered by the complexity of bacteria-host interactions and host variability in microbiologically uncontrolled conditions. While these difficulties can be partially resolved using gnotobiotic models harboring no or reduced microbiota, most host-microbe interaction studies are carried out in animal models with little relevance for fish farming. Here we studied host-microbiota-pathogen interactions in a germ-free and gnotobiotic model of rainbow trout (Oncorhynchus mykiss), one of the most widely cultured salmonids. We demonstrated that germ-free larvae raised in sterile conditions displayed no significant difference in growth after 35 days compared to conventionally-raised larvae, but were extremely sensitive to infection by Flavobacterium columnare, a common freshwater fish pathogen causing major economic losses worldwide. Furthermore, re-conventionalization with 11 culturable species from the conventional trout microbiota conferred resistance to F. columnare infection. Using mono-re-conventionalized germ-free trout, we identified that this protection is determined by a commensal Flavobacterium strain displaying antibacterial activity against F. columnare. Finally, we demonstrated that use of gnotobiotic trout is a suitable approach for the systematic identification of both endogenous and exogenous probiotic bacterial strains that may protect teleostean hosts against F. columnare and other pathogens. This study establishes a novel and ecologically-relevant gnotobiotic model that will improve the sustainability and health of aquaculture.

Jeffrey I Gordon - One of the best experts on this subject based on the ideXlab platform.

  • applying indirect open circuit calorimetry to study energy expenditure in gnotobiotic mice harboring different human gut microbial communities
    Microbiome, 2019
    Co-Authors: Ilia G Halatchev, David Odonnell, Matthew C Hibberd, Jeffrey I Gordon
    Abstract:

    Given the increasing use of gnotobiotic mouse models for deciphering the effects of human microbial communities on host biology, there is a need to develop new methods for characterizing these animals while maintaining their isolation from environmental microbes. We describe a method for performing open-circuit indirect calorimetry on gnotobiotic mice colonized with gut microbial consortia obtained from different human donors. In this illustrative case, cultured collections of gut bacterial strains were obtained from obese and lean co-twins. The approach allows microbial contributions to host energy homeostasis to be characterized.

  • extensive personal human gut microbiota culture collections characterized and manipulated in gnotobiotic mice
    Proceedings of the National Academy of Sciences of the United States of America, 2011
    Co-Authors: Andrew L. Goodman, George Kallstrom, Jeremiah J Faith, Alejandro Reyes, Aimee Moore, Gautam Dantas, Jeffrey I Gordon
    Abstract:

    The proportion of the human gut bacterial community that is recalcitrant to culture remains poorly defined. In this report, we combine high-throughput anaerobic culturing techniques with gnotobiotic animal husbandry and metagenomics to show that the human fecal microbiota consists largely of taxa and predicted functions that are represented in its readily cultured members. When transplanted into gnotobiotic mice, complete and cultured communities exhibit similar colonization dynamics, biogeographical distribution, and responses to dietary perturbations. Moreover, gnotobiotic mice can be used to shape these personalized culture collections to enrich for taxa suited to specific diets. We also demonstrate that thousands of isolates from a single donor can be clonally archived and taxonomically mapped in multiwell format to create personalized microbiota collections. Retrieving components of a microbiota that have coexisted in single donors who have physiologic or disease phenotypes of interest and reuniting them in various combinations in gnotobiotic mice should facilitate preclinical studies designed to determine the degree to which tractable bacterial taxa are able to transmit donor traits or influence host biology.

Dorothee Maria Gescher - One of the best experts on this subject based on the ideXlab platform.

  • gram negative bacteria aggravate murine small intestinal th1 type immunopathology following oral infection with toxoplasma gondii
    Journal of Immunology, 2006
    Co-Authors: Markus M Heimesaat, Stefan Bereswill, Andre Fischer, David Fuchs, Daniela Struck, Julia Niebergall, Hannahkatharina Jahn, Ildiko R Dunay, Annette Moter, Dorothee Maria Gescher
    Abstract:

    Oral infection of susceptible mice with Toxoplasma gondii results in Th1-type immunopathology in the ileum. We investigated gut flora changes during ileitis and determined contributions of gut bacteria to intestinal inflammation. Analysis of the intestinal microflora revealed that ileitis was accompanied by increasing bacterial load, decreasing species diversity, and bacterial translocation. Gram-negative bacteria identified as Escherichia coli and Bacteroides/Prevotella spp. accumulated in inflamed ileum at high concentrations. Prophylactic or therapeutic administration of ciprofloxacin and/or metronidazole ameliorated ileal immunopathology and reduced intestinal NO and IFN-gamma levels. Most strikingly, gnotobiotic mice in which cultivable gut bacteria were removed by quintuple antibiotic treatment did not develop ileitis after Toxoplasma gondii infection. A reduction in total numbers of lymphocytes was observed in the lamina propria of specific pathogen-free (SPF), but not gnotobiotic, mice upon development of ileitis. Relative numbers of CD4(+) T cells did not differ in naive vs infected gnotobiotic or SPF mice, but infected SPF mice showed a significant increase in the frequencies of activated CD4(+) T cells compared with gnotobiotic mice. Furthermore, recolonization with total gut flora, E. coli, or Bacteroides/Prevotella spp., but not Lactobacillus johnsonii, induced immunopathology in gnotobiotic mice. Animals recolonized with E. coli and/or total gut flora, but not L. johnsonii, showed elevated ileal NO and/or IFN-gamma levels. In conclusion, Gram-negative bacteria, i.e., E. coli, aggravate pathogen-induced intestinal Th1-type immunopathology. Thus, pathogen-induced acute ileitis may prove useful to study bacteria-host interactions in small intestinal inflammation and to test novel therapies based on modulation of gut flora.

John A Ellis - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of induction of porcine dermatitis and nephropathy syndrome in gnotobiotic pigs with negative results for porcine circovirus type 2
    American Journal of Veterinary Research, 2008
    Co-Authors: Steven Krakowka, Catherine Hartunian, David Shoup, Michael Rings, Gordon Allan, Alexander Hamberg, Yan Zhang, John A Ellis
    Abstract:

    Objective—To determine whether porcine dermatitis and nephropathy syndrome (PDNS) could be experimentally induced in gnotobiotic swine. Sample Population—Plasma samples from 27 sows and 20 conventional weaned piglets were obtained, and 30 gnotobiotic pigs were used in experiments. Procedures—3 experiments were conducted. Groups of 3-day-old gnotobiotic pigs were inoculated with pooled plasma samples obtained from healthy feeder pigs in a herd that was in the initial phases of an outbreak of respiratory disease; gross and histologic lesions of PDNS were detected in the inoculated pigs. In a second experiment, 2- and 3-day-old gnotobiotic pigs were inoculated with porcine reproductive respiratory syndrome virus (PRRSV) and with PRRSV-negative tissue homogenate containing genogroup 1 torque teno virus (g1-TTV). Lesions of PDNS were detected. Results—Pigs inoculated with pooled plasma or the combination of tissue-culture–origin PRRSV and g1-TTV tissue homogenate developed systemic hemostatic defects, bilatera...

  • evaluation of induction of porcine dermatitis and nephropathy syndrome in gnotobiotic pigs with negative results for porcine circovirus type 2
    American Journal of Veterinary Research, 2008
    Co-Authors: Steven Krakowka, Catherine Hartunian, David Shoup, Michael Rings, Gordon Allan, Alexander Hamberg, Yan Zhang, John A Ellis
    Abstract:

    OBJECTIVE: To determine whether porcine dermatitis and nephropathy syndrome (PDNS) could be experimentally induced in gnotobiotic swine. SAMPLE POPULATION: Plasma samples from 27 sows and 20 conventional weaned piglets were obtained, and 30 gnotobiotic pigs were used in experiments. PROCEDURES: 3 experiments were conducted. Groups of 3-day-old gnotobiotic pigs were inoculated with pooled plasma samples obtained from healthy feeder pigs in a herd that was in the initial phases of an outbreak of respiratory disease; gross and histologic lesions of PDNS were detected in the inoculated pigs. In a second experiment, 2- and 3-day-old gnotobiotic pigs were inoculated with porcine reproductive respiratory syndrome virus (PRRSV) and with PRRSV-negative tissue homogenate containing genogroup 1 torque teno virus (g1-TTV). Lesions of PDNS were detected. RESULTS: Pigs inoculated with pooled plasma or the combination of tissue-culture-origin PRRSV and g1-TTV tissue homogenate developed systemic hemostatic defects, bilaterally symmetric cutaneous hemorrhages, generalized edema, icterus, bilaterally symmetric renal cortical hemorrhage, dermal vasculitis with hemorrhage, and interstitial pneumonia consistent with a clinical and pathologic diagnosis of PDNS. The PRRSV RNAs and g1-TTV DNAs were detected in plasma; all pigs seroconverted to PRRSV, and all had negative results for porcine circovirus type 2 when tested by use of PCR assays. CONCLUSIONS AND CLINICAL RELEVANCE: These data suggested that PDNS is a manifestation of disseminated intravascular coagulation in swine. For the experimental conditions reported here, combined infection with g1-TTV and PRRSV was implicated in the genesis of these lesions.

  • Evaluation of the effects of porcine genogroup 1 torque teno virus in gnotobiotic swine.
    American journal of veterinary research, 2008
    Co-Authors: Steven Krakowka, John A Ellis
    Abstract:

    Objective—To determine whether porcine genogroup 1 torque teno virus (g1-TTV) can infect and cause disease in gnotobiotic swine. Sample Population—20 conventional baby pigs and 46 gnotobiotic baby pigs. Procedures—Porcine g1-TTV was transmitted from conventional swine to gnotobiotic pigs via pooled leukocyte-rich plasmas (n = 18) that had positive results for g1-TTV DNA. Bone marrow–liver homogenates that had positive results for torque teno virus (TTV) were used in 4 serial passages in gnotobiotic pigs (2 pigs/passage). A pathogenesis experiment was conducted with in vivo passages of g1-TTV in various groups of gnotobiotic pigs. Results—All g1-TTV inoculated pigs had no clinical signs but developed interstitial pneumonia, transient thymic atrophy, membranous glomerulonephropathy, and modest lymphocytic to histiocytic infiltrates in the liver after inoculation with the TTV-containing tissue homogenate; these changes were not detected in uninoculated control pigs or pigs injected with tissue homogenate dev...

André Bleich - One of the best experts on this subject based on the ideXlab platform.

  • Monitoring and contamination incidence of gnotobiotic experiments performed in microisolator cages.
    International journal of medical microbiology : IJMM, 2021
    Co-Authors: Marijana Basic, Silvia Bolsega, Anna Smoczek, Joachim Gläsner, Andreas Hiergeist, Claudia Eberl, Bärbel Stecher, André Gessner, André Bleich
    Abstract:

    Abstract With the increased interest in the microbiome research, gnotobiotic animals and techniques emerged again as valuable tools to investigate functional effects of host-microbe and microbe-microbe interactions. The increased demand for gnotobiotic experiments has resulted in the greater need for housing systems for short-term maintenance of gnotobiotic animals. During the last six years, the gnotobiotic facility of the Hannover Medical School has worked intensively with different housing systems for gnotobiotic animals. Here, we report our experience in handling, contamination incidence, and monitoring strategies that we apply for controlling gnotobiotic experiments. From our experience, the risk of introducing contaminants to animals housed in microisolator cages is higher than in isolators. However, with strict operating protocols, the contamination rate in these systems can be minimized. In addition to spore-forming bacteria and fungi from the environment, spore-forming bacteria from defined bacterial communities used in experiments represent the major risk for contamination of gnotobiotic experiments performed in microisolator cages. The presence/absence of contaminants in germ-free animals can be easily monitored by preparation of wet mounts and Gram staining of fecal samples. Contaminants in animals colonized with specific microorganisms need to be tracked with methods such as next-generation sequencing. However, when using PCR-based methods it is important to consider that relatively small amounts of bacterial DNA detected likely originates from food, bedding, or reagents and is not to be interpreted as true contamination.

  • Gnotobiotics: Past, present and future:
    Laboratory animals, 2019
    Co-Authors: Marijana Basic, André Bleich
    Abstract:

    Gnotobiotics or gnotobiology is a research field exploring organisms with a known microbiological state. In animal research, the development of Gnotobiotics started in the late 19th century with the rederivation of germ-free guinea pigs. Cutting-edge achievements were accomplished by scientists in the Laboratories of Bacteriology at the University of Notre Dame (LOBUND). The primary goals of Gnotobiotics were not only the development of the equipment required for long-term husbandry but also phenotypic characterization of germ-free animals. The first isolators were designed by Reynolds and Gustafsson as rigid-wall stainless steel autoclave-like chambers, which were subsequently replaced by Trexler's flexible-film polyvinyl plastic isolators. Flexible-film or semi-rigid isolators are commonly used today. The long-term maintenance of gnotobiotic rodents is performed in positive-pressure isolators. However, to facilitate gnotobiotic experimental procedures, short-term husbandry systems have been developed. Gnotobiotic animal husbandry is laborious and requires experienced staff. Germ-free animals can be rederived from existing rodent colonies by hysterectomy or embryo transfer. The physiology and anatomy of germ-free rodents are different from those of specified pathogen-free (SPF) rodents. Furthermore, to guarantee gnotobiotic status, the colonies need to be regularly microbiologically monitored. Today, Gnotobiotics provides a powerful tool to analyse functional effects of host-microbe interactions, especially in complex disease models. Gnotobiotic models combined with 'omics' approaches will be indispensable for future advances in microbiome research. Furthermore, these approaches will contribute to the development of novel therapeutic targets. In addition, regional or national gnotobiotic core facilities should be established in the future to support further applications of gnotobiotic models.

  • Maintaining and Monitoring the Defined Microbiota Status of Gnotobiotic Rodents
    ILAR journal, 2015
    Co-Authors: Werner Nicklas, Lydia Keubler, André Bleich
    Abstract:

    Gnotobiotic (germfree, defined colonized) rodents have become powerful tools to advance our understanding of the host-microbiome relationship. However, the maintenance and ultimately the monitoring of gnotobiotic rodents is a critical, labor-intensive, and costly process (e.g., sterility, not absence of specific pathogens, must be demonstrated in germfree animals). Here, we provide information on the housing and maintenance of gnotobiotic animals, elucidate prophylactic measurements to avoid contamination, and make specific recommendations for sampling procedures, sampling frequencies, and test methods.