We aim to uncover the manifold secrets of functional evolution of pathogens with respect to the host environments; clarify mechanisms in chronic and acute host interactions of gastrointestinal bacterial pathogens (e.g. Helicobacter spp., Campylobacter spp., Salmonella, E. coli); we unravel innate immune responses and cell-autonomous defence mechanisms; we investigate regulation on the host and bacterial side. We place a particular interest on immune evasive strategies of pathogens. We also explore new avenues how to apply this fundamental knowledge to novel antibacterial therapeutics, for instance pathoblockers.