40,41 Mongolian gerbils infected with cagA-deleted 7.13 H. pylori mutant strain showed increased colonization density and attenuated inflammation compared to those infected with 7.13 wild-type strain.42 CagA is associated with a Th1-polarized immune response,43 which mediates protection against H. pylori and clearance of infection.44,45 The beneficial and detrimental effects of CagA suggest that H. pylori needs to regulate CagA during colonization of H. pylori in the human stomach. This evidence concerns the gene S100A8 and infection.