S100A8 and infection: Further, microbial community structure of gerbils infected with wild-type H. pylori strain 7.13 was significantly different than the structure in gerbils infected with the cagA isogenic mutant (P = 0.006) (Fig. 2B), indicating that infection with H. pylori leads to alterations in the structure of the microbial community in a cagA-dependent manner.