A new lymph node infection model for Streptococcus suis serotype 2 in pigs.

Streptococcus suis (S. suis) is an important invasive porcine pathogen. Here, we describe a new lymph node infection model where 7 × 103 CFU S. suis serotype 2 were injected in the left cervical lymph node. In total, seven out of eight 5-week-old piglets developed clinical signs of disease. In all infected pigs, S. suis was reisolated from the infected lymph node and one or more additional sites. Immunohistochemically, S. suis antigen was located predominantly in the sinus. The results suggest that S. suis easily disseminates after lymph node infection and that the interaction with cells of the mononuclear phagocytic system, primarily in the lymph node sinus, plays an important role in host cell-pathogen interaction.