During the process of infection, Salmonella uses two specialized nanomachines known as Type 3 Secretion Systems (T3SS) that are encoded by Salmonella Pathogenicity Island-1 (SPI-1) (Collazo and Galán, 1997) and SPI-2 (Hensel, 2000), respectively, to inject virulence factors directly into host cells. Here, SPI1 is linked to infection.