Peritoneal culture alters Streptococcus pneumoniae protein profiles and virulence properties

We have examined the properties of Streptococcus pneumoniae cultured in the murine peritoneal cavity and compared its virulence-associated characteris tics to those of cultures grown in vitro. Analysis of mRNA levels for speci fic virulence factors demonstrated a 2.8-fold increase in ply expression an d a 2.2-fold increase in capA3 expression during murine peritoneal culture (MPC), Two-dimensional gels and immunoblots using convalescent-phase patien t sera and murine sera revealed distinct differences in protein production In vivo (MPC). MPC-grown pneumococci adhered to A549 epithelial cell lines at levels 10-fold greater than those cultured in vitro.