Reduced cytokine secretion and pathology observed in mice infected with plasmid-deficient C. muridarum and sacrificed early post-infection resolution (O’Connell et al., 2007; Lei et al., 2014) has been attributed to a failure to activate TLR2 (O’Connell et al., 2007; O’Connell et al., 2011). The gene discussed is TLR2; the disease is infection.