Fig. 1.

A simplified schematic representation of the molecular pathway of fish innate immune TLR and NLR receptor. TLR senses PAMPs/MAMPs derived from bacteria (PGN, LTA, LPS etc.), virus (genetic material), fungi etc. and transduces the signal via its cytoplasmic domain to trigger downstream molecules following activation of cytokines and interferons (IFN). Intracellular PAMPs such as MDP and iE-DAP are recognized by NOD receptors following activation of effector molecules and conversion of pro-cytokines to active cytokines.