SIVA1 and infection: We found that whereas infection with wild type strain PMSS1 leads to significant increase of ULF levels (Figs 7A and S4A) and downregulation of SIVA1 (Figs 7B and S4A), as well as p19ARF (Figs 7C and S4A) in the corpus and antrum, cagE- mutant has a diminished ability to do so, suggesting an important role of the T4SS signaling.