Probiotic-induced differential gene expression during Salmonella challenge in neonatal chicks

Salmonella remains an important enteric pathogen of poultry, primarily due to concerns regarding food-borne illness in humans consuming contaminated poultry products. Specific probiotic cultures are efficacious as a treatment for neonatal poultry to prevent enteric infections (competitive exclusion) due to the exquisite susceptibility of young chicks to pathogens in the hatchery and brooding environment. The objective of this experiment was to analyze transcriptional profiles in the ceca of neonatal chicks using the Arizona Gallus gallus 20.7K Oligo Array v1.0, following treatment with a probiotic culture derived from poultry with and without Salmonella enterica subsp. Enteritidis (SE) challenge. Chicks were obtained from a commercial hatchery, and challenged with SE upon arrival at the laboratory. One hour post-challenge, chicks were treated with a probiotic culture (FM-B11). Treatment groups included: Control (no challenge or treatment, vehicle only), SE (challenged only), B11 (treated only) and SE+B11 (challenged and treated). Samples were obtained at 12h and 24h post-treatment. We observed that administration of a Lactobacillus-based probiotic culture to chicks following challenge with SE reduced SE colonization of the cecae and resulted in differential expression of genes in the cecae. Among all four treatment groups, 309 genes were differentially expressed (p<0.05) at 12h, and 352 genes were differentially expressed (p<0.05) at 24h. Keywords: disease state analysis Eight experimental groups with 4 replicates each were analyzed. A reference RNA design was used for this microarray. Equal amounts of amplified RNA (aRNA) from all samples were pooled and labelled with the Alexa 647 to create the reference pool. Each individual sample was labelled with Alexa 555. Each slide was hybridized with both the reference pool and one sample.