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United States Department of Agriculture

Agricultural Research Service

Research Project: MOLECULAR ANALYSIS OF VIRULENCE DETERMINANTS OF SELECT BACTERIA IN FISH DISEASES

Location: Aquatic Animal Health Research

Title: Expression profiles of toll-like receptors in anterior kidney of channel catfish Ictalurus punctatus (Rafinesque), acutely infected by Edwardsiella ictaluri

Authors
item Wei Pridgeon, Yuping
item Russo, Riccardo
item Shoemaker, Craig
item Klesius, Phillip

Submitted to: Journal of Fish Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 9, 2010
Publication Date: May 1, 2010
Repository URL: http://hdl.handle.net/10113/55442
Citation: Pridgeon, J. W., Russo, R., Shoemaker, C.A., Klesius, P.H. 2010. Expression profiles of toll-like receptors in anterior kidney of channel catfish Ictalurus punctatus (Rafinesque), acutely infected by Edwardsiella ictaluri. Journal of Fish Diseases 33:497-505.

Interpretive Summary: The relative transcriptional levels of five toll-like receptors (TLR2, TLR3, TLR5, TLR20a, and TLR21) were studied in the channel catfish under normal and acutely infected conditions. Under normal conditions, the transcriptional levels of the five toll-like receptors were significantly lower than that of 18S rRNA internal control. Among the five TLRs studied, TLR20a and TLR5 were more abundant than TLR2 and TLR21. The transcriptional level of TLR3 was significantly lower than that of the other four TLRs. However, when channel catfish were acutely infected by Edwardsiella ictaluri through injection, the transcriptional levels of TLRs increased significantly at 6 hours post injection. Among the five TLRs studied, only TLR5’s transcription level was never significantly lower than that under normal uninfected condition. The amount of E. ictaluri in the anterior kidney increased at 12 and 24 hours post injection, but decreased at 36 and 48 hours post injection. Our results suggest that toll-like receptors are important components in the immune system in the channel catfish and their rapid transcriptional upregulation (within 6 hours post injection) in response to acute E. ictaluri infection might be important for survival from enteric septicemia of catfish.

Technical Abstract: Using quantitative PCR (QPCR), the relative transcriptional levels of five toll-like receptors (TLR2, TLR3, TLR5, TLR20a, and TLR21) were studied in the channel catfish, Ictalurus punctatus (Rafinesque), under normal and acutely infected conditions (1, 2, 4, 6, 12, 24, 36, and 48 h post injection (hpi)). Under normal conditions, the transcriptional levels of the five toll-like receptors were significantly lower than that of 18S rRNA (p <0.001). Among the five TLRs studied, TLR20a and TLR5 were more abundant than TLR2 and TLR21. The transcriptional level of TLR3 was significantly lower than that of the other four TLRs (p <0.001). However, when channel catfish were acutely infected by Edwardsiella ictaluri through intraperitoneal injection, the transcriptional levels of TLRs increased significantly (p <0.005) at 6 hpi. Among the five TLRs studied, only TLR5’s transcription level was never significantly lower than that under normal uninfected condition. The amount of E. ictaluri in the anterior kidney increased at 12 and 24 hpi, but decreased at 36 hpi and 48 hpi. Our results suggest that toll-like receptors are important components in the immune system in the channel catfish and their rapid transcriptional upregulation (within 6 hpi time frame) in response to acute E. ictaluri infection might be important for survival from enteric septicemia of catfish.

Last Modified: 8/27/2014
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