Expression of SipA, SopA, SopD and SopE2 effector proteins of Salmonella Typhimurium during murine salmonellosis.

GIACOMODONATO MN, UZZAU S, SARNACKI SH, RUBINO S AND CERQUETTI MC

Pucón, Chile

Congreso; ALAM 2006. XVIII Congreso Latinoamericano de Microbiología.; 2006

Asociación Latinoamericana de Microbiología

Salmonella Typhimurium harbours two Salmonella pathogenicity islands (SPIs) each encoding a type III secretion system for virulence proteins. Although there is increasing evidence for post invasion roles for SPI1, it has been commonly accepted that SPI1 genes are downregulated following the invasion process. We determined the expression of some SPI1 effector proteins at late stages of murine salmonellosis. To this purpose S. Typhimurium SipA, SopA, D, and E2 tagged (3xFLAG) strains were inoculated intraperitoneally (ip) or intragastrically (ig) to BALB/c mice. Animals were sacrificed at day 5 or 8 post ip or ig inoculation, respectively and intracellular bacteria were recovered from spleen and lymph nodes. SPI1 expression was analyzed by SDS-page and immunoblotting with anti-FLAG antibodies. Results showed that S. Typhimurium colonizing deep organs continues to express SipA, SopD and SopE2 several days after ip or ig infection. SopA was detected only at 18 hs post ip inoculation. This fact is likely to be related to the short half life of SopA.  Taken together, our results suggest that SPI1 effectors have potential actions at post invasion stages of the murine salmonellosis.  Acknowledgments: This work was supported by CONICET grant PIP5534 and ANPCyT grant PICT13366.