A Promising Recombinant Herpesvirus of Turkeys Vaccine Expressing PmpD-N ofBased on Elongation Factor-1 Alpha Promoter.

Abstract

The obligate intracellular Gram-negative bacteriumoften causes avian chlamydiosis and influenza-like symptoms in humans. However, the commercial subunitvaccine could only provide a partial protection against avian chlamydiosis due to poor cellular immune response. In our previous study, a recombinant herpesvirus of turkeys (HVT)-delivered vaccine againstand Marek's disease based on human cytomegalovirus (CMV) promoter (rHVT-CMV-) was developed and provided an effective protection againstdisease with less lesions and reduced chlamydial loads. In this study, we developed another recombinant HVT vaccine expressing the N-terminal fragment of PmpD (PmpD-N) based on human elongation factor-1 alpha (EF-1α) promoter (rHVT-EF-) by modifying the HVT genome within a bacterial artificial chromosome. The related characterization of rHVT-EF-was evaluatedin comparison with that of rHVT-CMV-. The expression of PmpD-N was determined by western blot. Under immunofluorescence microscopy, PmpD-N protein of both two recombinant viruses was located in the cytoplasm and on the cell surface. Growth kinetics of rHVT-EF-was comparable to that of rHVT-CMV-, and the growth rate of rHVT-EF-was apparently higher than that of rHVT-CMV-on 48, 72, and 120 h postinfection. Macrophages activated by rHVT-EF-could produce more nitric oxide and IL-6 than that activated by rHVT-CMV-. In this study, a recombinant HVT vaccine expressing PmpD-N based on EF-1α promoter was constructed successfully, and a further researchwas needed to analyze the vaccine efficacy.