ABSTRACT: The early interaction of Salmonella enterica serovar typhimurium DT104 with intact small intestinal mucosa was studied in a Small Intestinal Segment Perfusion (SISP) model. Intestinal segments were infected with or without Salmonella. Scrapings from jejunal segments were collected after perfusion for 0, 2, 4, or 8 hours. Details of the SISP experiment are described in: Niewold TA, Veldhuizen EJ, van der Meulen J, Haagsman HP, de Wit AA, Smits MA, Tersteeg MH, Hulst MM. Using the Operon 13K pig oligonucleotide array differences in host gene expression were recorded between infected and uninfected segments within a single pig (isogenic comparisons), and between identical treated segments collected from 3 individual SISP pigs, all responding markedly different to infection with Salmonella (inter-animal comparisons). A Small Intestinal Segment Perfusion (SISP) test was performed with 3 pigs (pig no. 2, 3, and 4) (cross-bred YorkshireM-CM-^W(Large WhiteM-CM-^WLandrace)). Two adjacent segments prepared in the mid-jejunum of each pig were perfused for 1 hour with Salmonella enterica serovar typhimurium DT104 suspended in peptone solution (10E-09 CFU/ml) or with peptone solution alone (mock infected segment) respectively. Subsequently, segments were perfused with peptone solution alone for a maximum period of 8 hours. At 2, 4, and 8 hours a part of the infected segment was dissected to obtain mucosal scrappings. The same was done at 0 and 8 hours for the uninfected (mock) control segment. RNA isolated from scrappings was used for microarray comparisons using the Operon 13K pig oligonucleotide array. 9 comparisons were done. For each of the 3 SISP pigs, expression in the 8 hours perfused infected segment, perfused for 8 hours, was compared to expression in its adjacent mock infected segment (3 isogenic comparisons, 8 hpi.). Expression in the infected segment of each SISP pig, dissected after 2 or 4 hours of perfusion, was compared to expression in an infected segment dissected from another SISP pig (2 versus 3, 2 versus 4, and 3 versus 4 / 3 comparisons at 2 hpi., and 3 comparisons at 4 hpi.). Dye-swaps were performed for each comparison. jejunum pig, host-microbe interaction, Salmonella enterica serovar typhimurium DT104.