VacA recognizes 321aa-340aa sequences. Synthesized peptides (Table 1) were dissolved in saline, and spotted on PVDF membrane. VacA also spotted on PVDF membrane for the positive control. The membrane was incubated without VacA (VacA(-)), or with H-VacA or VacA. The membrane was incubated with anti-VacA polyclonal antibody and then HRP-conjugated secondary antibody (n=3).