Taken together, as IgM is an important factor in the naïve host, e.g., as a natural antibody and in limiting bacterial survival, and IdeSsuis is not a critical virulence factor during bacteremia after experimental infection [16, 27], this leads us to assume an important role of IdeSsuis expression by downregulating the host immune response in the IgM-low microenvironments of colonization and early infection rather than in invasive disease. Here, CD40LG is linked to infection.