Finally, and differently from what has been observed in a previous study [38], where the S. suis IgA protease encoded by iga gene was characterized as a critical virulence factor using an isogenic iga mutant (equivalent to the S. suis Δzmp strain used herein), the S. suis Δzmp strain was as virulent as the wild-type strain in an pig intranasal model of infection. This evidence concerns the gene CD79A and infection.