Comparative Expression Analysis of Toll-Like Receptor Protein in Brain, Gill and Liver of Healthy and Diseased Empurau (Tor tambroides)

The toll-like receptor proteins are pattern recognition receptors (PRRs) that trigger the innate immune systems to detect and recognize the conserved pathogen-associated molecular patterns (PAMPs) to engage the early immunological recognition of various types of pathogens. Various pathogens can cause infections (e.g., dropsy disease) in many aquaculture species, leading to significant economic losses for the producers. Infectious dropsy is one of the bacterial hemorrhagic septicemia diseases characterized by the abnormal accumulation of water or other fluids in the whole body, especially in the abdomen or localized in different organs of the fish. Although Tor tambroides is one of the famous Malaysian mahseers, yet there is not enough information on their TLR repertoire to fully comprehend the underlying molecular regulation of pathogens recognition. This research aims to isolate the total RNA and to compare the toll-like receptor gene expressions on different organs of healthy and diseased Tor tambroides. TLR1, TLR3, TLR5, TLR7, and TLR9 have been selected from the whole Tor tambroides genome for primer design after being blasted with the transcriptomic data of Tor tambra. Gene expression analysis was performed via semi-quantitative RT-PCR using the cDNA of three isolated organs (brain, gill, and liver) from healthy and diseased Tor tambroides, respectively. Expression was detected in the diseased liver for TLR1, TLR3, TLR5, and TLR7 genes might suggest the role of TLRs in recognition of the invasion of pathogens. The pathogen focused on this research is Pseudomonas fluorescens. Identifying of the TLRs and their roles may contribute to a better understanding of the disease resistance mechanisms in Tor tambroides, as well as a new insight for drug design to regulate the immune response