Joshua Gong

Guelph Food Research Centre

Agriculture and Agri-Food Canada

E-mail: gongj@agr.gc.ca

Education:                  Ph.D. in Microbiology (1994), University of Guelph, Guelph, Ontario, Canada

M.Sc. in Microbiology (1983), Beijing Agricultural University, China

B.Sc. in Industrial Fermentation (1980), Wuxi College of Light Industry, China

Employment History:             

1999 - Present            Principal Research Scientist

                     Agriculture and Agri-Food Canada

                     Food Research Program, Guelph, Ontario, Canada

                     Research area: Animal gut microbiology and food safety/quality

1997 - 1999         Senior Research Associate

Department of Cell Biology, Neurobiology, and Anatomy

University of Cincinnati College of Medicine, Cincinnati, Ohio, USA

Research area: Signal transduction and DNA polymorphism of opioid receptors

1995 - 1997         Research Associate

Department of Medical and Molecular Genetics

Indiana University School of Medicine, Indianapolis, Indiana, USA

Research area: Opioid receptor mediated signal transduction and functions

1994 - 1995         Postdoctoral Fellow

Center for Food and Animal Research, Agriculture Canada, Ottawa, Ontario

Research area: Molecular ecology and phylogeny of ruminal bacteria

1988 – 1994        Research Assistant

Department of Microbiology, University of Guelph

Research area: Physiology of cellulose digestion and bacterial adhesion

Professional Appointments:

2004 - Present            Member of the Scientific Advisory Committee

Canadian Poultry Research Council

2002 - Present            Adjunct Professor

Department of Animal & Poultry Science

University of Guelph, Guelph, Ontario, Canada

2002 - Present            Adjunct Professor

Institute of Subtropical Agriculture, Chinese Academy of Sciences

Changsha, China 

Current Research Interests:

1.        Gut microbial ecology of domestic animals and fowls and interactions between gut bacteria and animal hosts

2.        Pre/probiotics to mitigate the use of dietary antibiotics and food-borne pathogens in food animal production

3.        Biotechnology of gut bacteria to enhance food safety and quality

Publications and Conference Presentations:

More than 50 peer-reviewed publications in internationally renowned scientific journals.  More than 100 conference presentations.

報告摘要

ECOLOGY, PATHOGENESIS, AND HOST RESPONSE TO CLOSTRIDIUM PERFRINGENS INFECTION IN BROILER CHICKENS

Joshua Gong

Guelph Food Research Centre, Agriculture & Agri-Food Canada, Canada gongj@agr.gc.ca

Clostridium perfringens (CP) causes necrotic enteritis (NE) in chickens, which has been the major target of prophylactic use of antibiotics in feed.  We have studied microbial ecology and chicken response to CP infection with an experimental infection chicken model, in order to enhance our knowledge for control of the disease.  Chickens were fed antibiotic-medicated (bacitracin, 55 mg/kg) or non-medicated diets, and were challenged with CP (10⁷ CFU/ml) through the diets at 18 days of age. Digesta and tissue samples were collected daily before and after the challenge, and were examined for cell proliferation of CP, gene expression of alpha-toxin, changes in the composition of ileal bacterial microbiota, and gene expression profiles in the spleens and ileum, in addition to recording animal performance.  The cell proliferation of CP was highly correlated to alpha-toxin production during the development of necrotic enteritis (NE).  The average CP counts in the ileal digesta of 5 log₁₀ CFU/g was shown to be a threshold for developing NE disease.  While major bacterial groups, such as Enterococcus genus and Enterobacteriaceae family, exhibited no change in their populations, the abundance of lactobacilli in the ileum was significantly reduced.  In particular, the change of L. avarius correlated negatively with the CP counts. The analysis of gene expression profiles indicated that many immune-associated genes were significantly up-regulated in CP-infected chickens.  These genes encode members of the Toll-like receptor pathway, antibody response, T cell markers, and inflammatory cytokines.  The expression of a subset of functionally relevant genes was validated through quantitative RT-PCR assays.  Both medicated and non-medicated chickens demonstrated similar annotation profiles with cell activity and regulation being the most dominant biological processes across time.  Functional studies are underway to verify some observations from microarray analysis.   We also had a separate effort to identify novel C. perfringens virulence factors in NE pathogenesis through the analysis of the genome sequence of an isolate known to cause NE disease in broilers.  Genome comparison with other non-poultry strains revealed a number of putative genes unique to this isolate, including a putative hemolysin, a capsule biosynthesis locus, and several antibiotic resistance genes.  We are developing a microarray based on this strain, which will be used to further identify and characterize genes related to NE disease.