Submitted to: United States Animal Health Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 10/14/2003
Publication Date: 5/1/2004
Citation: Kapczynski, D.R., King, D.J. 2004. NDV Vaccines - Field Versus Experimental Studies. United States Animal Health Association Proceedings, p.520-521, 2003. Interpretive Summary: Newcastle disease 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 protection against U.S. exotic Newcastle disease (END) virus. The results indicate that although NDV vaccines are able to induce protective immunity from lethal'END challenge they do not appear to protect against viral replication.
Technical Abstract: The objectives of the present study were to extend the knowledge of protection against U.S. exotic Newcastle disease (END) virus by live and inactivated Newcastle disease virus (NDV) B1 vaccines and determine immunity of commercial birds following lethal challenge with a California 2002 (CA02) END virus isolate. Initial experimentation was designed to assess protection of SPF chickens receiving a single dose of a commercially available inactivated or live NDV B1 vaccine from CA02 challenge, as well as different doses of live vaccine followed by challenge. In a final experiment, birds from commercial field operations (broiler-breeders and broilers) in Georgia undergoing routine NDV vaccination programs were challenged with CA02. The results indicate both live and inactivated vaccines protected SPF chickens from lethal CA02 challenge. However, the vaccines were unable to prevent virus shed, determined by virus isolation from oral and cloacal swabs. Commercial broilers appeared susceptible to CA02 challenge, in spite of receiving two live virus vaccinations in the field at 1 and 17 days-of-age. Seventy-five percent of these birds succumb to challenge. Commercial broiler-breeders were resistant to challenge and very few birds shed CA02 virus. These results demonstrate that NDV vaccines protect against lethal challenge, and the timing of vaccination for commercial broilers should be evaluated in END outbreak situations.