Analysis of porcine differential gene expression following challenge with Salmonella enterica serovar Choleraesuis using suppression subtractive hybridization

Swine-adapted Salmonella enterica subsp. enterica serovar Choleraesuis (S. Choleraesuis) is the pathogen most frequently isolated from diseased pigs and may affect host gene expression in a species-specific manner. To characterize the porcine transcriptional response to S. Choleraesuis infection, the mRNA profiles from the mesenteric lymph nodes of three non-infected and three experimentally infected pigs at 24 h post-inoculation were analyzed by suppression subtractive hybridization (SSH). Forty-four up-regulated and 44 down-regulated genes were revealed by differential cDNA screening of 384 forward and 288 reverse subtracted cDNA clones. The DNA sequence of the cDNA clones identified genes with a role in a variety of cellular functions as well as gene products of unknown function. Seven up-regulated genes (CXCL10, CXCR4, SDCBP, DNAJA1, HSPH1, HSP90 and ANXA5) and two functionally related genes (HSP70 and DNAJA4:pDJA1) were selected for further analysis based on their predicted roles in infection and immunity. Real-time RT-PCR was performed using RNA collected from a time course of infection spanning from the acute phase (8 h) to the chronic phase (21 days) to confirm and quantitate the up-regulation of the SSH-enriched genes. Correlating with the clinical signs of infection (fever, diarrhea and lethargy), the most dramatic induction of gene expression for all nine genes occurred at 48 h post-inoculation. This investigation further defines the porcine response to a host-adapted strain of Salmonella by revealing the differential expression of genes with a role in a variety of host cellular functions including innate immunity and cytoskeleton regulation.