ABSTRACT
The Fusion (F) and Haemagglutinin-Neuraminidase (HN) genes of Newcastle disease virus (NDV) and the glycoprotein B (gB) gene of infectious laryngothracheitis virus (ILTV) as well as a LacZ reporter gene were all inserted into a nonessential gene of fowlpox virus (FPV) 017 strain by homologous recombination. The NDV and ILTV genes were each under the control of a fowlpox virus immediate early/late promoter (LP2EP2) while the LacZ reporter gene expression cassette was regulated by a P11 late promoter. A recombinant FPV harboring the F, HN and gB genes as well as the LacZ gene, designated as rFPV-F/HN/gB/LacZ, was obtained after ten cycles of blue plaque purification. The presence of the NDV and ILTV genes was confirmed by PCR. The expression of the recombinant proteins in rFPV-F/HN/gB/LacZ were characterized by Western blot (F and gB proteins) and indirect immunofluorescence test (F, HN and gB proteins). The results demonstrated that all four foreign proteins, which were encoded within a 10 kb gene fragment, could be expressed authentically and efficiently. Compared to the parental virus, rFPV-F/HN/gB/LacZ showed no obvious difference with respect to virus replication and cytopathogenic effects in chicken embryo fibroblasts (CEF) cell culture. Overall, our work suggests that FPV can be a useful live virus vector for the expression of multi- foreign genes against multiple avian pathogens.