The Interferon-a Genes from Three Chicken Lines and Its Effects on H9N2 Influenza Viruses

The interferon-(alpha) genes from three chicken lines were cloned by a direct PCR technique, and the effects of recombinant protein expressed in a prokaryotic system on highly pathogenic H9N2 influenza viruses were investigated. The cloned ChIFN-(alpha) gene encoded a protein of 193 amino acids with a signal sequence of 31 amino acids and mature peptides of 162 amino acids. Comparison of ChIFN-(alpha) sequences, detected six amino acids substitutions at positions 50, 58, 65, 81, 181, and 183. Homology analysis indicated that ChIFN-(alpha) genes could be subdivided into two lineages, SH-ChIFN-(alpha) and WJ-ChIFN-(alpha). In addition, both SH-ChIFN-(alpha) and WJ-ChIFN-(alpha) were expressed with the N-terminal 6 consecutive histidine residues in a high-level prokaryotic expression system. Recombinant chicken interferon-(alpha) (rChIFN-(alpha)) protein has anti-VSV activity of more than 1 × 10 8 U/mg. Moreover, High concentration (10,000 U) of rSH-ChIFN-(alpha) resulted in over 40% inhibition of the H9N2 virus infection in chicken embryos (Ovo), and 100% inhibition from one day-old to five day-old chickens (Vivo). The results suggested that rChIFN-(alpha) is a potential agent against many Chicken viral strains.