Response of turkeys to simultaneous vaccination with hemorrhagic enteritis and Newcastle disease viruses.
The effects of single and combined vaccination of turkeys against hemorrhagic enteritis virus (HEV) and Newcastle disease virus (NDV) were investigated. Dual vaccination of turkeys with NDV-B1 and HEVp30 or marble spleen disease virus (MSDV) enhanced white mottling of the spleens and the apoptosis rate in spleen cells (P < 0.05). In addition, simultaneously vaccinated turkeys had fewer HEV-infected spleen cells at 4 days postvaccination than turkeys given HEVp30 or MSDV alone. The anti-HEV antibody response was significantly reduced at 14 days postvaccination (P < 0.05), whereas the anti-NDV antibody response was enhanced (P < 0.05) in turkeys vaccinated with HEVp30 + NDV-B1. Further, the effect of dual vaccination on macrophage function was studied. Spleen cells from NDV-B1-vaccinated turkeys were primed to produce nitric oxide (NO) after stimulation in vitro with lipopolysaccharide. Spleen cells from HEVp30- or MSDV-vaccinated turkeys did not produce NO after in vitro stimulation. In dual-vaccinated turkeys, the priming effect of NDV-B1 was reduced in comparison with single-inoculated birds.