Streptococcus suis type 2 (SS2) is one of the most important zoonotic pathogens world wide. Muramidase released protein (MRP) is a key virulence factor of SS2. In this paper, both SS2 strains, HA9801, naturally with MRP expression, isolated from Jiangsu province and SH006444, without MRP, from Shanghai, were used to study adhesion and invasion of SS2 to tonsil epithelial cells from neonatal rabbit. Adhesion counting assay demonstrated high adhesive levels of both strains. Scanning and transmission elect...