Protection of Chickens against Very Virulent Infectious Bursal Disease Virus (IBDV) and Marek's Disease Virus (MDV) with a Recombinant MDV Expressing IBDV VP2

Abstract

To develop a herpes virus vaccine that can induce immunity for an extended period, a recombinant Marek's disease (MD) virus (MDV) CVI-988 strain expressing infectious bursal disease virus (IBDV) host-protective antigen VP2 at the US2 site (rMDV) was developed under the control of an SV40 early promoter. Chickens vaccinated with the rMDV showed no clinical signs and no mortality and 55% of the chickens were considered protected histopathologically after challenge with very virulent IBDV (vvIBDV), whereas all of the chickens vaccinated with the conventional IBDV vaccine showed no clinical signs and were protected. Chickens vaccinated with the CVI-988 or chickens in the challenge control showed severe clinical signs and high mortality (70-75%) and none of them were protected. Also, the rMDV conferred full protection to chickens against vvMDV just as the CVI-988 strain did, whereas 90% of the challenge control chickens died of MD. Antibody levels against IBDV and MDV following the vaccination increased continuously for at least 10 weeks. No histopathological lesions in the rMDV-vaccinated chickens and no contact transmission of the rMDV to their penmates were confirmed. These results demonstrate that an effective and safe recombinant herpesvirus-based IBD vaccine could be constructed by expressing the VP2 antigen at the US2 site of the CVI-988 vaccine strain.

Development of an Effective Polyvalent Vaccine against both Marek's and Newcastle Diseases Based on Recombinant Marek's Disease Virus Type 1 in Commercial Chickens with Maternal Antibodies

“…In the poultry industry, four recombinant viruses (rFPV [1,5,8,14,18,25,31,34,35,59], rHVT [13,17,28,41,44,53], adenovirus [51], and rMDV1 [45,47,49,54,62]) that express foreign antigens of other avian pathogens (including NDV [14, 17, 24, 28-30, 35, 47, 53, 58], MDV [31,33,42,44,69], infectious bursal disease virus [1,5,13,18,19,51,62], avian influenza virus [2,3,5,56,59,61,65,66], avian leukosis virus [34], and avian reticuloendotheliosis virus [8]) have been developed, and these viruses showed significant vaccine efficacy against a variety of avian diseases. Further, rHVT, rMDV1, and rFPV expressing NDV antigens have been constructed and used to FIG.…”

Current status of vaccines against infectious bursal disease

“…Here, difficulties in the secretion or translocation of the expressed viral protein across the bacterial cell wall could be the limiting factor (Li et al, 2006;Mahmood et al, 2007). (Tsukamoto et al, 1999), avian adenovirus (Francois et al, 2004) and T4 bacteriophage (Cao et al, 2005) have been used as vector viruses for expressing VP2, the only antigen inducing protective immunity to IBDV. HVT has been used as a safe and effective vaccine against Marek's disease for decades; as it is poorly sensitive to interference with maternally derived antibodies, HVT has been proposed as a vector for IBD (Darteil et al, 1995;Tsukamoto et al, 2002) and other diseases.…”

Complete, Long-Lasting Protection against Lethal Infectious Bursal Disease Virus Challenge by a Single Vaccination with an Avian Herpesvirus Vector Expressing VP2 Antigens

“…We previously developed a recombinant MDV (rMDV) expressing VP2 antigen under control of the simian virus 40 (SV40) early promoter and showed that it was safe for chickens. However, the efficacy was partial and did not persist for a long time (39,40). Recombinant HVT (rHVT) expressing the VP2 antigen under the control of a cytomegalovirus (CMV) promoter also induced partial protection in chickens when one dose was used (8).…”