Submitted to: Molecular Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2007
Publication Date: 3/6/2007
Citation: Uthe, J.J., Bearson, S.M., Royaee, A.R., Lunney, J.K., Stabel, T.J., Zhao, S., Tuggle, C.K. 2007. Porcine differential gene expression in response to Salmonella enterica serovars Choleraesuis and Typhimurium. Molecular Immunology. 44(11):2900-2914. Interpretive Summary: Background: Swine infections with Salmonella serovars are an animal health issue (serovar Choleraesuis) and food safety concern (serovar Typhimurium). The goal of this research study was to identify swine genes that may be expressed differently during infection with the two Salmonella serovars. This information could explain why Choleraesuis causes a more severe disease in pigs than Typhimurium, as well as clarify why Typhimurium is much more likely to cause disease in humans. Description: Both Salmonella serovars caused gastroenteritis in the pigs and caused gene expression changes in their lymph nodes. However, an obvious difference was observed between the two Salmonella infections: clinical signs of disease and changes in gene expression occurred approximately 24 hours earlier in the Typhimurium-infected pigs compared to the Choleraesuis-infected pigs, suggesting a quicker immune response by the pigs to infection with Salmonella Typhimurium. Impact: Defining the immune response of pigs to Salmonella infection may identify targets for disease control, contribute to developing diagnostic assays for Salmonella-carrier animals, and assist in identifying Salmonella-resistant lines of pigs. Furthermore, since Choleraesuis causes disease in pigs and Typhimurium causes disease in humans, identifying differences in gene expression during swine infection with the two Salmonella serovars has contributed to our basic knowledge of host specificity.
Technical Abstract: Using suppression subtractive hybridization (SSH) and real-time PCR, an investigation of the porcine response to infection with Salmonella enterica serovars Choleraesuis (narrow host range) and Typhimurium (broad host range) revealed different transcriptional profiles. Ten genes identified by SSH as up-regulated in the mesenteric lymph nodes at 24 hours (h) post-inoculation (p.i.). in the serovar Choleraesuis-infected pigs (ARPC2, CCT7, HSPH1, LCP1, PTMA, SDCBP, VCP) and in the serovar Typhimurium-infected pigs (CD47/IAP, CXCL10, SCARB2) were analyzed by real-time PCR at 8 h, 24 h, 48 h, 7 days (d) and 21 d p.i. A comparison between the two Salmonella infections revealed significant differences in transcriptional induction early in the infection (8 h – 24 h) for the serovar Typhimurium-infected pigs, whereas the serovar Choleraesuis-infected pigs exhibited significantly higher levels of gene expression at the later time points (24 h - 21 d), except for HSPH1. A similar gene expression trend was observed for immune-related genes involved in the T helper 1 (Th1) and Th2 response, inflammation and innate immunity. Initial repression of gene expression in the serovar Choleraesuis-infected pigs at 8 h p.i. was followed by extended transcriptional activation during the 21 d infection (IFNG, INDO, SOCS1, STAT1, IL1B, IL6, IL8, SLC11A1). The serovar Typhimurium-infected swine presented a more transient induction of immune-related genes (IFNG, INDO, IRF1, SOCS1, STAT1, IL1B, IL8, SLC11A1) early in the infection (24-48 h) followed by a significant repression of IL12A, IL12B, IL4, IL8 and CSF2.