Molecular characterization of duck (Anas platyrynhos) Toll-like receptors, mRNA expressions profile in day-old duckling’s tissues and cytokine response to in vitro TLR agonsists stimulation

Abstract

TLR repertoire of duck, profiling of their mRNA expression in a range of duckling tissues and cytokine gene expressions upon TLR agonists stimulation in in vitro assay have been investigated. All ten TLR genes orthologous to chicken TLR repertoire were found in duck. Duck TLR genes showed 77-83% similarity at amino acid level to their chicken counterparts. All ten TLRs-TLR1LA, 1LB, 2A, 2B, 3, 4, 5, 7, 15 and 21 mRNA expressions were significantly higher in bursa than other tissues studied, whereas in muscle all TLRs mRNA expressions were significantly lower except for TLR15 (P>0.01). TLR7 gene expression was significantly higher in spleen, bursa and also in lung tissues (P>0.01). The cytokine gene expression levels in duck PBMCs upon LPS and poly I:C stimulation have been quantified. IL-1g gene expression level in LPS stimulated duck PBMC culture was significantly higher at both 12 h and 24 h time intervals (P>0.05). However, there were no significant changes in IFN-ã gene expression levels in poly I:C stimulated duck PBMC culture at both the intervals. TLR gene expression in young ducklings together with cytokine response upon LPS stimulation demonstrates the innate preparedness of younger birds to encounter pathogens and their functional ability to respond to their ligands.