Interactions between DRB1*15:01-DRB5*01:01 MHC II molecules, C. diff. exotoxins and T-cells may alternately play a critical role in CDI pathogenesis, and additional work is needed to understand whether and how the host IgA response is differentially impacted by the combined effects of haplotype and transcriptional modifications. This evidence concerns the gene CD79A and clostridium difficile infection.