Data from: A host-adapted auxotrophic gut symbiont induces mucosal immunodeficiency

The microbiome holds great promise as a source of novel therapeutic
targets for many diseases. Mining for causative microorganisms that impact
processes underlying disease states should utilize Koch’s postulates. Here
we show a functional screen for the bacterial microbiota of intestinal
immunoglobulin A (IgA)-deficient mice; we identified a novel Gram-negative
bacterium, proposed to be named as Tomasiella immunophila that induces and
degrades IgA in mouse intestine. T. immunophila is auxotrophic for the
bacterial cell wall amino sugar N-acetylmuramic acid (MurNAc). T.
immunophila secretes IgA-degrading enzymes into outer membrane vesicles
that preferentially degrade rodent antibodies with kappa but not lambda
light chains. We propose this study uncovers a new paradigm for the role
of symbionts in immunodeficiency that can ultimately be applied to human
disease.