Protection of turkeys from hemorrhagic enteritis with a recombinant fowl poxvirus expressing the native hexon of hemorrhagic enteritis virus.

Hemorrhagic enteritis (HE) is an economically important disease of turkeys caused by a type II aviadenovirus, hemorrhagic enteritis virus (HEV). The vaccines currently available to the commercial poultry producer are highly effective in preventing disease outbreaks; however, they are immunosuppressive. A recombinant fowl poxvirus (rFPV) expressing the native hexon of HEV has been shown to induce an anti-HEV humoral immune response in turkeys. In this study, the rFPV expressing the native hexon of HEV was compared with a commercial HEV vaccine (vxHEV) for its ability to protect turkeys from virulent HEV challenge. Complete protection from the enteritis of HE was achieved in experimental groups vaccinated with either the rFPV or the vxHEV. Lymphocyte stimulation was measured in turkeys inoculated with rFPV, vxHEV, or a sublethal dose of HEV or not inoculated. No statistically significant immunodepression was observed in turkeys receiving the rFPV.