Expression and Characterization of the Fusion Protein of Newcastle Disease Virus Strain F48E8 in Insect Cells

The fusion protein gene of strain F48E8 of Newcastle disease virus was amplified with RT-PCR, and cloned into the pGEM-T vector and named pGEM-NDF. Then, F gene was released from pGEM-NDF by digestion with BamHI and XbaI, and ligated to baculovirus transfer vector, pFastBac1, which was digested with BamHI and XbaI. The ligation yielded a recombinant plasmid, pFast-NDF. The results of sequencing and PCR showed that F gene had been cloned into baculovirus genome correctly. After transfecting sf9 cells with pFast-NDF, the recombinant baculovirus was recovered from the cells. The results of IFA and Western-blot assay indicated that F gene was expressed well in sf9 cells. Furthermore, the F protein was present on the cell membrane, and sf9 cells were fused at 96 hours post-infection, which suggested that F protein had the activity of cell fusion. Animal tests showed that the fusion protein expressed in insect cells induced neutralizing antibody against NDV in mice. All these results provided foundation for the development of F protein.