Table 1.

Functions of SPIs in the pathogenicity of Salmonella.

Pathogenicity Island	Virulence Factor	Function	Reference
SPI-1	SipA, SipB	invasion of intestinal epithelial cells; development of SCV; encoding the effector proteins important for actin cytoskeleton rearrangements; induction of IL-8 and Salmonella-elicited epithelial chemoattractant secretion; membrane ruffling that	[12,33,37,38,39,40,41,42]
SPI-2	SseF, SseG	mediates processes required for bacterial replication within host macrophages; SCV localization; inhibition of fusion between lysosomes and SCVs; avoidance of NADPH oxidase-dependent killing by macrophages; encoding of effector, chaperon and translocon proteins	[12,33,37,38,39,40,43]
SPI-3	MisL	host cell attachment and long-term colonization; intramacrophage survival	[37,38]
SPI-4	SiiE	mediation in adhesion to epithelial cells; involvement in intracellular survival and systemic infection by S. Typhimurium	[12,37,38]
SPI-5	SopB	important for S. Dublin virulence; involvement in intracellular survival and systemic infection by S. Typhimurium; membrane ruffling; activation of pro-inflammatory response	[12,37,38,44]
SPI-6	Tar4, SciG, SciS	combating host resistance to pathogen colonization; involvement in intracellular survival and systemic infection by S. Typhimurium	[37,45]
SPI-7	-	virulence factor for typhoid fever	[46]
SPI-11	PagC, PagD, EnvE, EnvF	involvement in intracellular survival and systemic infection by S. Typhimurium; resistance to antimicrobial peptides; survival within macrophages	[37,38]
SPI-12	SspH2	intracellular survival	[38]
SPI-13	STM3118, STM3119	survival within macrophages	[38]
SPI-14	LoiA	encoding the LoiA protein necessary for the invasion of the intestinal epithelium by S. Typhimurium; regulation of SPI-1 genes	[37,38,40]
SPI-16	STM0557	long-term colonization	[38]
SPI-19	-	necessary for survival within macrophages and initial colonization by S. Pullorum in chicken	[47]