Whereas the IgM cleaving activity of IdeSsuis was shown to be important for reduction of complement-mediated hemolysis, labeling of sheep erythrocytes with IgM and opsonization of S. suis with IgM and complement, an impact of IgM cleavage in induction of disease, especially meningitis, could not be demonstrated. The gene discussed is CD40LG; the disease is meningitis.