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. 2019 Jul 31;9:270.
doi: 10.3389/fcimb.2019.00270. eCollection 2019.

Salmonella Pathogenicity Island 1 (SPI-1) and Its Complex Regulatory Network

Free PMC article

Salmonella Pathogenicity Island 1 (SPI-1) and Its Complex Regulatory Network

Lixin Lou et al. Front Cell Infect Microbiol. .
Free PMC article


Salmonella species can infect a diverse range of birds, reptiles, and mammals, including humans. The type III protein secretion system (T3SS) encoded by Salmonella pathogenicity island 1 (SPI-1) delivers effector proteins required for intestinal invasion and the production of enteritis. The T3SS is regarded as the most important virulence factor of Salmonella. SPI-1 encodes transcription factors that regulate the expression of some virulence factors of Salmonella, while other transcription factors encoded outside SPI-1 participate in the expression of SPI-1-encoded genes. SPI-1 genes are responsible for the invasion of host cells, regulation of the host immune response, e.g., the host inflammatory response, immune cell recruitment and apoptosis, and biofilm formation. The regulatory network of SPI-1 is very complex and crucial. Here, we review the function, effectors, and regulation of SPI-1 genes and their contribution to the pathogenicity of Salmonella.

Keywords: SPI-1; Salmonella; T3SS; effector; immune response; regulation.


Figure 1
Figure 1
Schematic diagram of the SPI-1-related T3SS needle apparatus in contact with a host cell.
Figure 2
Figure 2
Scheme of the SPI-1 regulatory network in Salmonella. The green arrows indicate activation, and the red lines with flat ends represent inhibition.

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