Construction Of A Recombinant Fowlpox Virus Expressing HA, NA Gene Of AIV And GB Gene Of ILTV

Fowlpox virus (FPV) is an important vector for expression of animal viral genes,and it has played a significant role in the control of avian diseases. FPV has been usedas a vector to generate a variety of recombinant vaccines; some of them have alreadybeen commercialized. It is very significant that developing a recombinant FPVvaccine which are based on multi-valent antigen, especially for the poultry industrysince co-infection of different pathogens are often occurred in many current poultryfarms.Avian Influenza (AI), Infectious Laryngotracheitis (ILT) and fowlpox are threeserious respiratory diseases which have made great economic losses in poultryindustry in recent years. Nowadays, vaccines made by traditional methods have beenproved that these adequate protections defend these diseases. However, there areseveral disadvantages for these vaccines, for example, they can not be differentiatedfrom those generated from natural infections, and killed vaccines are expensive andinconvenient in mass vaccination. So, new generation of vaccines which are safe andeasily distinguish from wild-type viruses are in urgent needed.The Haemagglutinin (HA) and Neuraminidase (NA) genes of H9N2 lowlypathogenic AIV and the glycoprotein B (gB) gene of ILTV as well as a LacZ reportergene were all inserted into a nonessential region of FPV 017 strain by homologousrecombination. The AIV and ILTV genes were under the control of FPV immediateearly/late promoter (LP2EP2), while the LacZ reporter gene expression cassette wasregulated by a P11 late promoter. A recombinant FPV harboring the HA, NA and gBgenes as well as the LacZ gene, designated as rFPV-HA/NA/gB, was obtained after sixpassages of blue plaque purification. The presence of the AIV and ILTV genes wasconfirmed by PCR. The expression of the recombinant proteins in rFPV-HA/NA/gBwere characterized by Western blot and indirect immunofluorescence test (HA, NAand gB proteins, respectively). The results demonstrated that all the four foreignproteins which were encoded within a 10 kb gene fragment could be expressedauthentically and efficiently.