One of the major virulence factors of H.
pylori is the vacuolating toxin VacA . VacA is
expressed as a 140-kDa protoxin and undergoes proteolytic
processing to yield an 88-kDa secreted toxin . VacA is
secreted through an autotransporter pathway as a
soluble protein into the extracellular space, and a proportion
also remains attached to the bacterial cell surface