Differential gene expression of antimicrobial peptides β defensins in the gastrointestinal tract of Salmonella serovar Pullorum infected broiler chickens.

Salmonella enterica serovar Pullorum causes substantial mortality in chicks as well as results in persistent infection and vertical transmission in layer birds. An effective innate immune response in the early stages of infection could reduce bacterial colonization and mortality in chicks and persistency of infection in later stages. β Defensins (AvBDs) are now considered as one of the key components of innate immunity in avian species. In the present study, we quantified the mRNA expression levels of AvBDs (1-14) by real-time PCR in the gastrointestinal (GI) tissues (duodenum, jejunum, ileum and caecum) of 3-day-old broiler chicks after 24 h of oral infection with Salmonella Pullorum. Quantitative real-time PCR analysis revealed significant (P < 0.05) upregulation of AvBD3, 4, 5, 6 and 12 and a significant (P < 0.05) down regulation in the expressions of AvBD10, 11, 13 and 14 in one or few GI tissues, while no significant changes were observed for AvBD1, 2, 7, 8 and 9 gene expressions in any of the GI tissues investigated upon infection with S. Pullorum. Most substantial change in gene expression was found for AvBD5, being significantly (P < 0.01) upregulated in most of the GI tissues investigated. The differential expression levels of β defensins shed light on tailored innate immune response induced by S. Pullorum during the early stages of infection in chicks.