|MARTIN, ALISON - Pfizer Animal Health|
|HADDAD, EID - Pfizer Animal Health|
Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/2012
Publication Date: 8/7/2012
Citation: Kapczynski, D.R., Martin, A., Haddad, E.E., King, D.J. 2012. Protection from clinical disease against three highly virulent strains of Newcastle disease virus after in ovo application of an antibody-antigen complex vaccine in maternal antibody-positive chickens. Avian Diseases. 56(3):555-560. DOI: 10.1637/9980-110311-Reg.1.
Interpretive Summary: Newcastle disease virus (NDV) is considered to be one of the most important viral diseases of poultry worldwide. Newcastle disease vaccination is widely practiced in the USA with the majority of commercial birds receiving multiple vaccinations during their lifetime. The objectives of the present study were to extend the knowledge of vaccine protection against different isolates of exotic Newcastle disease (END) virus by vaccinating chickens still inside the egg. Chicken embryos were vaccinated and then hatched for challenge. The results indicate that this type of NDV vaccine can induce protective immunity from lethal–END challenge and is effective at limiting viral replication.
Technical Abstract: Worldwide, Newcastle disease virus (NDV) remains one of the most economically important diseases of poultry. Current vaccination strategies for commercial poultry include the use of inactivated and live NDV vaccines that typically induce protection against less virulent field viruses. The value of any vaccine in ND control is enhanced by demonstrated efficacy against diverse challenge strains including exotic Newcastle disease (END) challenge. However, veterinary management practices typically employ these vaccines in the presence of maternal antibody to minimize production losses and not for protection from an END challenge. In these studies, we tested the efficacy of a newly developed antigen-antibody complex Newcastle disease (ND) vaccine delivered in ovo. Commercial, maternal-antibody positive broiler chickens were vaccinated in ovo with a commercial liveB1- LaSota NDV complexed with NDV-specific antiserum (Newplex®) and challenged at weekly intervals after hatch. Challenge viruses included the virulent NDV strain Texas GB, and two END viruses, one from the 2002-2003 outbreak in California (CA) and the other from a 1997 END outbreak in South Korea (SK). Results demonstrate that maternal antibody was able to provide approximately 50% protection in either vaccinated or control chickens at 7 days of age following Texas GB challenge. However, with challenge at 14 days or later, most all control birds died whereas all vaccinated birds were protected. Challenge with the CA or SK END viruses in chickens at 28 days of age resulted in 100% protection of vaccinated birds, whereas all control birds died. In addition, vaccinated birds displayed decreased incidence of viral shedding in oral and cloacal swabs than control birds. Finally, antibody titers were significantly higher in vaccinated chickens, as determined by ELISA and hemagglutinin-inhibition tests, than non-vaccinated controls. Taken together, these results demonstrate the efficacy of antigen-antibody complexed vaccines delivered in ovo to protect commercial poultry.