Only recently, it was reported that especially members of Proteobacteria are able to induce T cell-dependent serum IgA responses in conventionally housed mice to protect them from lethal sepsis.49 In this study, commensal Helicobacter muridarum was identified as the driving species, which would induce mucosal IgA-secreting plasma cells as well as IgA+ bone marrow plasma cells.49 Our data suggest that dysbiosis in DC-LMP1/CD40 mice affects the dissemination of bacteria, inducing systemic IgG as well as IgA production. The gene discussed is CD40; the disease is Sepsis.