Expression analysis of TLR20 and TLR21 genes in channel catfish Ictalurus punctatus challenged by different bacteria and virus

LU Yang;WANG Qi-long;LI Min;CHEN Song-lin;SHA Zhen-xia;Key Laboratory of Sutainable Development of Marine Fisheries,Ministry of Agriculture,Yellow Sea Fisheries Research Institute,Chinese Academy of Fishery Sciences;College of Fisheries and Life Science,Shanghai Ocean University;

TLR20,TLR21 Channel catfish Pathogens Real-time quantitative

Toll-like receptor(TLR)is a kind of pattern recognition receptor with the function of immune defense,while TLR20 and TLR21 belong to a specific branch-non-mammalian TLRs. Expression of channel catfish Ictalurus punctatus TLR20 and TLR21 genes in the head kidney,intestine, liver and spleen was tested by quantitative real-time PCR at 0h,12h,24h,48h,72h and 7d after infection by Aeromonas hydrophila,Edwardsiella tarda,Streptococcus iniae and channel catfish hemorrhage reovirus(CCRV),respectively.The results showed that all the four pathogens induced the two genes to change their relative expression levels in catfish main immune tissues,and the expression changes were specific.Expression of the two genes was highly different after infection by A.hydrophila. The trends of expression of the two genes were similar after infection by E.tarda,and the expressions were up-regulated in liver.S.iniae induced 4,360-fold change in expression level of TLR20 in liver, much higher than TLR21(257.8-fold).The expression of the two genes was up-regulated in liver and head kidney,while down-regulated in intestine and spleen after infection by CCRV.All the results demonstrated the core function of TLR20 and TLR21 genes in channel catfish.This finding will offer theoretical reference for the study of fish disease defense mechanism and provide a new approach for developing more effective vaccines and immune therapies.