Toll-like receptors (TLRs) are a group of highly conserved molecules that initiate innate immune responses to pathogens by recognizing structural motifs. In response to pathogen associated molecular patterns (PAMPs), TLRs induce the production of reactive oxygen and nitrogen intermediates (ROI and RNI), inflammatory cytokines and up regulate the expression of co-stimulatory molecules, subsequently initiating adaptive immunity. Ten chicken TLR genes have been identified and their association with various diseases has been ascertained. This review concerns chicken toll-like receptors, their structure, expression, signalling, and their role in innate and adaptive immunity and disease resistance. It is concluded that TLR genes could be used as molecular markers for genetic selection for the improvement of disease resistance and TLR agonists as potential adjuvants in future vaccines.
