Splenic clearance of B. suis strains 1330 (♦) and 1330ΔctpA (▪) following inoculation. Mice were intraperitoneally inoculated with strains, and the splenic CFU counts were determined at 1, 3, 5, 7, or 9 weeks postinoculation. Each data point represents the mean values from five inoculated mice.