Differential gene expression profiles of beta-defensins in the crop, intestine, and spleen using a necrotic enteritis model in 2 commercial broiler chicken lines

Abstract

Changes in the expression levels of avian beta-defensin (AvBD) mRNA were evaluated in necrotic enteritis (NE) disease model in 2 genetically disparate commercial broiler chicken lines: Ross and Cobb. The NE was initiated in the gut by a previously established co-infection model using oral Eimeria maxima infection followed by a Clostridium perfringens challenge. Among the 14 AvBD types examined, there was a tissue-specific expression of AvBD transcripts: AvBD1, AvBD7, and AvBD9 in the crop; AvBD8, AvBD10, and AvBD13; in the intestine and AvBD1 and AvBD7 in the spleen. The 2 different commercial broiler chicken lines showed differential gene expression patterns of AvBD transcripts following co-infection with E. maxima and C. perfringens, with R-line chickens generally showing higher expression levels than the C strain. Both chicken strains showed enhanced gene expression levels of proinflammatory cytokines, such as IL-1 beta, IL-6, IL-17F, and TNFSF15 in spleen, and TNFSF15 in intestine, whereas IL-17F was significantly increased only in the intestine of R-line chickens following NE infection. Although the exact nature of interactions between defensins and cytokines in determining the outcome of host innate immune responses to the pathogens of NE remains to be investigated, the differences in gene expression levels of beta-defensins and proinflammatory cytokines in the intestine, crop, and spleen could explain the predisposed disease resistance and susceptibility to NE in the 2 commercial broiler chicken lines.