title: Molecular identification and expression analysis of Toll-like receptor 3 in common carp Cyprinus carpio.
abstract: The Toll-like receptor (TLR) family is an evolutionarily conserved component of the innate immune system that responds to specific pathogen-associated molecular patterns (PAMP) during infections. TLR3 is a putative pattern recognition receptor (PRR) for dsRNA, a common by-product of viral replication. This study reports the identification and characterization of a full-length orthologue of TLR3 (CcTLR3) in the common carp Cyprinus carpio. It is 2899 base pairs (bp) encoding 904 amino acid residues with a calculated molecular mass of 102 744 Da and an estimated isoelectric point of 6.89. The deduced amino acid sequence is characterized by a signal peptide, 14 leucine-rich repeat (LRR) motifs, a transmembrane domain and a Toll-interleukin (IL)-1 receptor (TIR) domain. Real-time polymerase chain reaction (RT-PCR) analysis indicated that CcTLR3 mRNA transcripts could be detected in a wide range of tissues. Although C. carpio is resistant to grass carp Ctenopharyngodon idella reovirus (GCRV), after injection with GCRV, CcTLR3 expression was downregulated from 24 h post-injection (P < 0.05) and returned to control levels at 72 h post-injection (P > 0.05). Antiviral effector Mx mRNA expression, however, was upregulated from 24 h post-injection (P < 0.05) and recovered to control levels at 96 h post-injection (P > 0.05). The results provide a better understanding of the anti-GCRV mechanism and antiviral immune responses in fish, and help to develop suitable strategies to reduce viral diseases in fish.
authors.affiliation: Northwest A&F University, Shaanxi Key Laboratory of Molecular Biology for Agriculture, Yangling 712100, China.
authors.forename: C
authors.initials: C
authors.lastname: Yang
authors.forename: J
authors.initials: J
authors.lastname: Su
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002347:Carps / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D003001:Cloning, Molecular; D005393:Fish Diseases / Q000235:genetics / Q000276:immunology / Q000821:virology; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D010802:Phylogeny; D012087:Reoviridae / Q000276:immunology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D051196:Toll-Like Receptor 3 / Q000235:genetics* / Q000378:metabolism
chemical_list: D029941:Fish Proteins; D051196:Toll-Like Receptor 3