CD40LG and infection: Increase of serum IgM binding to the surface of S. suis cps14 within 14 days post infection and killing of the homologous and a heterologous cps14 strain after intranasal cps14 challenge in reconstituted blood (Fig. S1 in Supplementary data file 3) suggests induction of IgM by experimental mucosal infection and is in agreement with IgM cross-reacting between closely related S. suis strains [16].