An efficient bivalent vaccine against duck Tembusu and duck plague viruses based on ribosomal skipping of DHAV-1 2A1 and abundant expression of DPV protein.

Duck Tembusu virus (DTMUV) and duck plague virus (DPV) are common duck pathogens that cause significant annual economic losses to the poultry industry. In this study, a recombinant virus DPV-(UL49-2A1-E) expressing the DTMUV E protein was successfully constructed and evaluated for its immunological effects using a duck-derived viral protein with ribosome jumping function, duck hepatitis A virus type 1 (DHAV-1) 2A1, to ligate a DTMUV -truncated E protein positioned before the termination codon of the DPV high-abundance expression protein pUL49. Immunofluorescence and western blot analyses revealed that the E protein was normally expressed in DPV-(UL49-2A1-E)-infected duck embryo fibroblasts. The insertion of the E gene did not affect the proliferation of the vector virus, and the recombinant virus DPV-(UL49-2A1-E) demonstrated good stability both in vivo and in vitro. Moreover, DPV-(UL49-2A1-E) showed excellent immunogenicity, inducing the production of neutralising and enzyme-linked immunosorbent assay antibodies against DTMUV and DPV in ducklings after a single immunisation, and effectively conferred resistance to challenges with lethal DTMUV and DPV two weeks following immunisation. The recombinant virus also exhibited a certain level of clearance of lethal viruses, indicating that a single immunisation with DPV-(UL49-2A1-E) conferred 100 % protection to ducks against DTMUV and DPV infections. In summary, the use of the DHAV-1 2A1 ribosomal skip function for the expression of exogenous proteins is feasible. The recombinant vaccine DPV-(UL49-2A1-E), constructed using this method, is highly efficient and provides a new approach for the development of multivalent vaccines.