Mucosal interleukin (IL)-1β mRNA levels in gerbils at 4, 12, and 24 weeks after inoculating with Helicobacter pylori or without H pylori (control) in the pyloric mucosa (antrum) and fundic mucosa (corpus). Mean (SEM) values are presented. *p<0.05, **p<0.01, ***p<0.001 compared with control; †p<0.05, ††p<0.01, †††p<0.001 compared with the cagG knockout mutants; ‡‡p<0.01, ‡‡‡p<0.001 compared with the virD4 knockout mutants.