Functions of the Salmonella pathogenicity island 2 (SPI-2) type III secretion system effectors

Salmonella enterica serovars cause severe disease in humans, such as gastroenteritis and typhoid fever. The bacteria are able to invade and replicate within host cells, including epithelial cells and macrophages. Pathogenesis of Salmonella is facilitated by a type III secretion system (T3SS) encoded by genes of Salmonella pathogenicity island 2 (SPI-2). Intracellular replication occurs in a specialized membrane compartment, the Salmonella-containing vacuole (SCV), and depends on translocation of approximately 30 effector proteins via the SPI-2 T3SS into the host endomembrane system and cytoplasm. In this review we discuss the many different functions of these effectors, which range from maintaining the integrity of the SCV and its juxtanuclear location, to interference with the host cytoskeleton and immune signalling.