Title: Improved Newcastle disease vaccine approaches using virus strains selected on antigenic composition Author
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 19, 2009
Publication Date: October 23, 2009
Citation: Miller, P.J. 2009. Improved Newcastle disease vaccine approaches using virus strains selected on antigenic composition [abstract]. Precongress Cientifico Avicola, Investigacion Aplicada, S.A. (IASA)'s 9th Scientific Forum, Convencion Annual de Especialistas en Ciencias Avicolas de Mexico (ANECA), August 14-17, 2009, Acapulco, Mexico. pg. 2. Technical Abstract: Virulent Newcastle disease viruses (NDV) from the 1971 to 2002 U.S. outbreaks, are the same serotype but a different genotype than current vaccine strains. It is widely recognized that an efficacious Newcastle disease (ND) vaccine made with any NDV does induce protection against morbidity and mortality from a virulent NDV challenge. However, those ND vaccines do not protect vaccinates from infection and viral shed from such a challenge. Multiple inactivated and live vaccines prepared from NDV corresponding to different genotypes were compared in 4-week old SPF White leghorn chickens to determine if the phylogenetic distance between vaccine and challenge strain influences amount of challenge virus shed. Three weeks post-vaccination, serum was analyzed for antibody content using a hemagglutination inhibition assay against each of the vaccine antigens and a commercial NDV ELISA. After challenge with virulent CA 2002 (genotype V) or TXGB/1948 (genotype II), the birds were examined daily for morbidity and mortality and were monitored at selected intervals for virus shedding. Significantly less virus was shed from birds vaccinated with an inactivated homologous vaccine (same genotype as challenge) compared to chickens vaccinated with genotypically heterologous vaccines. Subsequent experiments comparing the amount of challenge virus shed from chickens vaccinated with live vaccines of B1 and LaSota (genotype II), Ulster (genotype I), and recombinant viruses that express the hemagglutinin-neuraminidase (HN) gene or the HN and fusion (F) genes of CA 2002 (genotype V) showed similar results. NDV vaccines formulated to be genetically closer to potential outbreak viruses likely provide better ND control by reducing virus transmission from infected birds.