Molecular cloning, tissue distribution and function analysis of duck TLR7

Area of Science:

• Immunology
• Molecular Biology
• Veterinary Science

Background:

• Toll-like receptors (TLRs) are key in innate immunity, detecting pathogen-associated molecular patterns (PAMPs).
• TLR7 specifically recognizes viral single-stranded RNA and is vital for antiviral responses.
• Ducks (Anas platyrhynchos) are natural hosts for avian influenza virus, making their immune responses relevant.

Purpose of the Study:

• To characterize the structure and function of duck Toll-like receptor 7 (duTLR7).
• To investigate the expression patterns and immune-activating potential of duTLR7 in ducks.

Main Methods:

• Obtained full-length duck TLR7 cDNA using RT-PCR and RACE.
• Analyzed duTLR7 gene structure and protein sequence.
• Quantified duTLR7 transcript expression in various tissues.
• Stimulated duck cells with TLR agonists (R848, poly(I:C)) and measured downstream immune gene expression.

Main Results:

• The duTLR7 gene comprises 5'-UTR, 3'-UTR, and an open reading frame encoding a 1089-amino acid protein.
• DuTLR7 shares high sequence identity with TLR7 from other vertebrates.
• DuTLR7 transcripts were widely expressed in healthy ducks, notably in the liver, kidney, and thymus.
• R848 and poly(I:C) stimulation significantly induced duTLR7 expression and downstream immune mediators like IFN-β, NF-κB, and IRF7.

Conclusions:

• Duck TLR7 (duTLR7) possesses structural and functional characteristics consistent with its role in innate immunity.
• DuTLR7 is broadly expressed and inducible, playing a significant role in the duck's antiviral immune response.