The full-length cDNA of fusion protein (F) gene of newcastle disease virus (NDV)strain F48E9 was amplified by RT-PCR and inserted into pcDNA3 under the control of human cytomegalovirus (hCMV) immediate early enhancer and promoter. The resulting recombinant plasmid pcDNA3-F was transformed by electroporation into attenuated Salmonella typhimurium strain ZJ111 (dam(-) and phoP(-)), which was then used to transfect the Vero cells. The DNA and RNA dot blotting revealed that the F gene was transcribed into mRNA in the Vero cells. There was expression of the F protein as shown by indirect immunofluorescent assay. The expression began at 48 h post-infection and increased thereafter, as indicated by ELISA. A 55 kD band of the F protein was identified by SDS-PAGE and Western blotting. These results clearly show that the expressed fusion protein was immuno-reactive with chicken anti-NDV serum.