SPI1 and infection: Salmonella express two different T3SS translocons required for infection; T3SS-1, encoded by Salmonella Pathogenicity Island 1 (SPI-1) along with a subset of effector proteins, and T3SS-2, encoded by Salmonella Pathogenicity Island 2 (SPI-2) along with another cohort of effector proteins (reviewed in Malik-Kale et al., 2011).