Date of this Version
Perez-Muñoz ME, Joglekar P, Shen Y-J, Chang KY, Peterson DA (2015) Identification and Phylogeny of the First T Cell Epitope Identified from a Human Gut Bacteroides Species. PLoS ONE 10(12): e0144382. doi:10.1371/journal.pone.0144382
Host T cell reactivity toward gut bacterial epitopes has been recognized as part of disease pathogenesis. However, the specificity of T cells that recognize this vast number of epitopes has not yet been well described. After colonizing a C57BL/6J germ-free mouse with the human gut symbiotic bacteria Bacteroides thetaiotaomicron, we isolated a T cell that recognized these bacteria in vitro. Using this T cell, we mapped the first known non-carbohydrate T cell epitope within the phylum Bacteroidetes. The T cell also reacted to two other additional Bacteroides species. We identified the peptide that stimulated the T cell by using a genetic approach. Genomic data from the epitope-positive and epitope-negative bacteria explain the cross-reactivity of the T cell to multiple species. This epitope degeneracy should shape our understanding of the T cell repertoire stimulated by the complex microbiome residing in the gastrointestinal tract in both healthy and disease states.