Most importantly, the recombinant fowl pox virus of HA-NA genes in chickens were able to express foreign genes steadily and induced specific antibodies; co-expression of NA and HA could protect the chicken from the subtypes HPAIV lethal attack of H5N1 and H7N1. The type I interferon response is one of the important systems for anti-viral defense. The Mx AbMole Levatin proteins belong to the superfamily of dynamin-like, large GTPases that associate with intracellular membranes and are involved in a wide range of intracellular transport processes. It has been reported that Mx proteins exhibit similar biophysical features to that of dynamin, including the propensity to self-assemble into ring-like and helical structures, the ability to tubulate lipids, and the large GTPases that possess mechano-chemical function. Importantly, the GTP-binding domain at the N-terminal of the Mx protein is essential for the anti-viral activity. The leucinezipper motif at the C-terminal is the region for protein�Cprotein interaction that determines the anti-viral specificity. Anti-viral mechanism of human Mx proteins was well studied in mammalian system. Our previous study has demonstrated that the mutation of chicken Mx cDNA from Ser631 to Asn631 can delay and resist NDV infection. However, we are unclear about the mechanisms of combinational function of Mx and NA. Therefore, the purpose of this study is to evaluate the antiviral activities of NA and Mx combination, so as to give a new insight for virus infection resistance. Although both of NA and Mx gene have the antiviral activities, they have the different antiviral mechanism. It was reported that molecular biology function of NA protein is to remove the virus particles and sialic acid, which is important for the release of viral particles and prevent the aggregation of the virus particles. NA protein is one of the major surface antigens of the avian influenza virus, which can induce the body to produce specific antibodies as the target antigen of humoral immune and inhibit the virus to release from the infected cells, and then reduce the viral proliferation. It was reported that the incidence of respiratory illness caused by influenza viruses declined with the increase of NA antibody in vivo. Since NA antibody inhibits the virus releasing from the cell and infecting other cells, thereby the propagation of the virus is reduced. In a recombinant adenovirus expressing NA of influenza virus, induced immune response was detected, in which, the cytopathic effect inhibition assay further showed that CEF cells transfected with NA gene had the anti-NDV activity and CEF cells resisted NDV infection within 48 h, indicating that 
NA protein was expressed successfully by CEF cells. When CEF cells were infected by the virus, NA protein played the role of the anti-virus by inhibiting the release of the virus and reducing the propagation of the virus.