Molecular cloning and antiviral function analysis of pigeon interferon lambda(piIFN-λ).

Type III interferons (IFN-λ) are critical components of the interferon system, serving as key antiviral cytokines in the innate immune response of epithelial cells. However, the biological role of pigeon IFN-λ (piIFN-λ) remains poorly understood. In this study, we cloned and characterized the biological effects of piIFN-λ. Our results reveal that the open reading frame (ORF) of piIFN-λ is 561 base pairs long, encoding a protein consisting of 186 amino acids. The amino acid sequence of piIFN-λ shares 76.3%, 65.1%, 64%, 60.2%, and 31.2% identity with those of shearwater, chicken, duck, goose, and human IFN-λ, respectively. Notably, recombinant piIFN-λ, expressed in a prokaryotic system, exhibited dose‑dependent antiviral activity against both vesicular stomatitis virus (VSV) and H9N2 avian influenza virus (AIV). Mechanistically, luciferase reporter assays indicated that recombinant piIFN-λ activated the Mx and ISRE promoters and enhanced Mx, OAS and PKR mRNA expression in a dose‑dependent manner in DF-1 cells. These findings suggest that piIFN-λ may hold potential as a therapeutic agent for avian viral diseases.