Abstract In order to investigate the immune responses to the nucleoprotein (NP) of Avian influenza virus, NP gene cut from recombinant plasmid pVAX-NP was subcloned into a eukaryotic expression vector pCAGGS with an avian-derived promoter. The recombinant plasmid pCAGGS-NP was obtained after PCR identification and sequencing. Then the positive pCAGGS-NP was subjected to transfect eukaryocyte and to immunize SPF chickens. Indirect florescent assay (IFA) was engaged to detect the transient expression of NP, and ELISA was used to detect the serum antibody of the immunized chickens which was against to NP protein. These results showed that NP was successfully expressed both in vitro and in vivo and had good immunoreactivity.
