FIG. 6.

Type III secretion-associated genes are expressed at a greater level in serovar Typhimurium (STm) 4/74 compared to serovar Choleraesuis (SCS) A50 during batch culture and infection of porcine alveolar macrophages. n-Fold induction of sipC (panel A) and sseC (panel B) relative to yejA in serovar Typhimurium 4/74 (gray bars) and serovar Choleraesuis (black bars) during mid-logarithmic-phase growth in LB broth (A₆₀₀, ca. 0.7) and 4, 8, and 24 h postinfection of primary porcine alveolar macrophages is shown. The n-fold induction of sipC mRNA relative to yejA during mid-logarithmic-phase growth in LB was also measured for different serovar Typhimurium and Choleraesuis strains (panel C). Secreted proteins prepared from the same cultures as used for RNA extraction were probed for SipC protein by Western (W.) blotting with a SipC-specific monoclonal antibody (panel C, bottom). All P values for n-fold differences, <0.05.