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Infections of piglets during the weaning period can be fatal and thus, lead to an increased mortality. During that period, the protective effect of colostrum is missing and piglets are exposed to new antigens, as for instance food antigens. Furthermore, due to the change to solid food, the intestine is extremely stressed. Consequently, sequelae can increase the susceptibility, especially to Salmonella infections. The involved diarrhea, low feed conversion and the reduced gain in weight affect piglets? performance. Since the EU-wide prohibition of feed antibiotics in 2006, the necessity arose to investigate alternatives which decrease piglets? susceptibility to infections. The addition of probiotics to the nutrition may be an alternative. However, the molecular principle of probiotics as treatment or prophylaxis in e.g. Salmonella infections is poorly understood.
The aim of this study was to characterize the porcine intestinal gene expression during postnatal development focusing on the weaning phase. For this purpose healthy subjects but also Salmonella and Salmonella/probiotic treated groups were studied, respectively.
Intestinal tissue samples (Ileum and ascending colon) from piglets were collected within 7 ? 56 days after birth. In addition, samples from Salmonella typhimurium infected piglets as well as another infected group that was simultaneously treated with the probiotic strain E. faecium NCIMB 10415 were taken.
Gene expression analyses were conducted by means of two color microarray experiments using the microarray-platform Pigoligoarray . Clustering of genes revealed groups with differing expression in Salmonella infected piglets compared to the control and the Salmonella/probiotic treated group. Pathway analyses were performed using the web based tool DAVID .
Initial results point to genes with increased or decreased expression after Salmonella infection in colon. Interestingly, a restitution of these genes was observed in the probiotic treated group. Pathway analyses showed that genes with restituted expression are involved in local acute inflammatory responses (BioCarta ) or cell adhesion (KEGG ).
This study represents the first characterization of the gene expression after Salmonella/E. faecium treatment during intestinal development in piglets. The presented results provide a better understanding of probiotic function in pathogen associated infection during weaning.