3rd Annual BMRP Investigator Meeting - Abstract

Cloning the Gut Metagenome:  A Strategy to Detect Pro-inflammatory Substances Produced by Intestinal Bacteria

Gerald W. Tannock1,a, R. Balfour Sartor2, Jens Walter1 and Aaron Lerner2

1Department of Microbiology and Immunology, University of Otago (Dunedin, New Zealand); 2Division of Digestive Diseases and Nutrition, University of North Carolina at Chapel Hill (Chapel Hill, North Carolina, U.S.A.)

The general goal of the research was to identify antigens produced by gut bacteria associated with chronic, T lymphocyte-dependent inflammation of the colon in experimental animal models of inflammatory bowel disease (IBD).  Two animal models were used: the HLA-B27 transgenic rat and interleukin-10-deficient mouse.  There were two objectives for the first year of our study.

  • Objective 1:  Derive DNA libraries of the gut microbiota metagenomes associated with colitis in the two rodent models to overcome the problem of non-cultivability of the majority of the members of the gut microbiota.
  • Objective 2:  Identify the bacterial metagenomic clones that encode antigens that induce T cell proliferation and interferon-gamma secretion using cells derived from rodents with active colitis.


Two metagenomic clone libraries were prepared, one from each experimental animal model, totaling 12,000 clones.  The libraries were tested for the production of antigenic substances by measuring T cell proliferation (thymidine incorporation), and for stimulation of interferon-gamma secretion by immunocytes (ELISA assay).  Twelve clones from the rat library that induced proliferative responses and interferon-gamma secretion, and 15 clones from the mouse library that induced interferon-gamma secretion by immunocytes were detected.  The objectives of the first year of research were, therefore, accomplished.  We have detected bacterial antigens that are likely involved in the production of colitis in the animals.  We will determine the biochemical nature of these bacterial substances.  Similar antigens may be involved in the production of human IBD, therefore, our results will lead to investigations of the response of human immune cells to these substances.

aPrincipal Investigator