Figure 2: Schematic representation of host-pathogen interactions during pathogenesis of Salmonella infections in human. For the first stages of salmonellosis, Salmonella Pathogenicity Island (SPI1) function is required, i.e. the entry of Salmonella into nonphagocytic cells by triggering invasion and the penetration of the gastrointestinal epithelium and also for the onset of diarrhoeal symptoms. The function of SPI2 is required for later stages of the infection, i.e. systemic spread and the colonization of host organs [43].