Characterization of Whooper Swan ( Cygnus cygnus) Interferon α: Prokaryotic Expression, Biological Activities, and Physicochemical Characteristics.

Whooper swan Cygnus cygnus interferon alpha (CyIFN-α) gene was amplified from genomic DNA in the liver of whooper swan, which encodes a 192-amino acid protein containing a 29-amino acid signal peptide. Bioinformatics analysis showed it containes 7 cysteine residues and 5 alpha helices. After expression in prokaryote, purification and renaturation, CyIFN-α was analyzed on its physicochemical property and antiviral activity. In chicken embryo fibroblasts, CyIFN-α exerted more superior anti-vesicular stomatitis virus (VSV), avian influenza virus (AIV), and Newcastle disease virus (NDV) activity than chicken IFN-α, an effective therapeutic agent used for viral infections clinically. Contrarily, these antiviral activities were abrogated by rabbit anti-CyIFN-α in vitro. Moreover, CyIFN-α was shown to be highly sensitive to trypsin, however, it remained stable despite changes in pH and temperature. In addition, CyIFN-α induced the transcription of Mx1, ISG12, and IFIT5 (ISG58) genes, as well as the expression of Mx1 protein, in a time-dependent manner. In conclusion, we first cloned and expressed CyIFN-α and tested its biological activity in vitro. Our findings facilitate further research on the role of type I IFN in antiviral defense responses in whooper swan and other Natatores. [ABSTRACT FROM AUTHOR]