Submitted to: International Poultry Forum Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: November 3, 2006
Publication Date: January 22, 2007
Citation: Miller, P.J., Estevez, C., Yu, Q., Suarez, D.L., King, D.J. 2007. Protection against exotic Newcastle disease virus (NDV) challenge of chickens vaccinated with NDV vaccines made from different genetic lineages [abstract]. International Poultry Forum Proceedings. p. 31. Technical Abstract: Vaccines for control of Newcastle Disease (ND) have been used for over fifty years in the United States. The available ND vaccines, both live and killed have been shown to prevent mortality and symptoms of disease. However, they typically do not prevent vaccinated birds from becoming infected and shedding virus that may infect susceptible birds. The purpose of this study was to determine if vaccination with Newcastle Disease virus (NDV) strains that are genetically more similar to the challenge strain reduce the shedding of challenge virus. Two experiments were conducted using four-week-old specific pathogen-free Leghorn chickens. In the first experiment chickens were subcutaneously vaccinated with inactivated vaccines utilizing strains B1, Ulster, CA 2002, Pigeon 84, Alaska 196, or uninfected allantoic fluid as control. In the second experiment chickens were vaccinated with either live or inactivated vaccines using a recombinant Anhinga 1993 NDV with either its own hemagglutinin neuraminidase (HN) gene or with a HN substitution from CA 2002, a live B1 commercial vaccine, an inactivated challenge virus (CA 2002) vaccine, or appropriate control vaccines. Three weeks post-vaccination seroconversion was assessed by ELISA and hemagglutination inhibition (HI) assays performed against each of the vaccine antigens. After challenge with virulent CA2002, birds were examined daily and monitored at selected intervals for virus shedding. All treatments except for the sham vaccinated controls induced greater than 83% protection from clinical disease and mortality. More importantly, the vaccines homologous with the challenge virus reduced oral shedding significantly more than the antigenically heterologous vaccines. Consequently, vaccines formulated to be antigenically closer to circulating virulent viruses can provide better Newcastle Disease control by reducing virus transmission from vaccinated birds.