title: Development of an improved vaccine evaluation protocol to compare the efficacy of Newcastle disease vaccines.
abstract: While there is typically 100% survivability in birds challenged with vNDV under experimental conditions, either with vaccines formulated with a strain homologous or heterologous (different genotype) to the challenge virus, vaccine deficiencies are often noted in the field. We have developed an improved and more stringent protocol to experimentally evaluate live NDV vaccines, and showed for the first time under experimental conditions that a statistically significant reduction in mortality can be detected with genotype matched vaccines. Using both vaccine evaluation protocols (traditional and improved), birds were challenged with a vNDV of genotype XIII and the efficacy of live heterologous (genotype II) and homologous (genotype XIII) NDV vaccines was compared. Under traditional vaccination conditions there were no differences in survival upon challenge, but the homologous vaccine induced significantly higher levels of antibodies specific to the challenge virus. With the more stringent challenge system (multiple vaccine doses and early challenge with high titers of vNDV), the birds administered the homologous vaccine had superior humoral responses, reduced clinical signs, and reduced mortality levels than those vaccinated with the heterologous vaccine. These results provide basis for the implementation of more sensitive methods to evaluate vaccine efficacy.
authors.affiliation: Southeast Poultry Research Laboratory, 934 College Station Rd., Athens, GA 30605, USA; Department of Veterinary Pathology, College of Veterinary Medicine, The University of Georgia, College of Veterinary Medicine, 501 D. W. Brooks Dr., Athens, GA, USA. Electronic address: stivaliscgs@gmail.com.
authors.forename: Stivalis
authors.initials: S
authors.lastname: Cardenas-Garcia
authors.affiliation: Department of Veterinary and Biomedical Sciences, Animal Disease Research and Diagnostic Laboratory, South Dakota State University, Brookings, SD 57007, USA. Electronic address: diego.diel@sdstate.edu.
authors.forename: Diego G
authors.initials: DG
authors.lastname: Diel
authors.affiliation: Southeast Poultry Research Laboratory, 934 College Station Rd., Athens, GA 30605, USA. Electronic address: leonardo.susta@ars.usda.gov.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Susta
authors.affiliation: Investigación Aplicada, S.A. de C.V., 7 Norte 416, Col. Centro, Tehuacán, Puebla CP 75700, Mexico. Electronic address: elucio@grupoidisa.com.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Lucio-Decanini
authors.affiliation: Southeast Poultry Research Laboratory, 934 College Station Rd., Athens, GA 30605, USA. Electronic address: qingzhong.yu@ars.usda.gov.
authors.forename: Qingzhong
authors.initials: Q
authors.lastname: Yu
authors.affiliation: Department of Veterinary Pathology, College of Veterinary Medicine, The University of Georgia, College of Veterinary Medicine, 501 D. W. Brooks Dr., Athens, GA, USA. Electronic address: corbrown@uga.edu.
authors.forename: Corrie C
authors.initials: CC
authors.lastname: Brown
authors.affiliation: Southeast Poultry Research Laboratory, 934 College Station Rd., Athens, GA 30605, USA. Electronic address: patti.miller@ars.usda.gov.
authors.forename: Patti J
authors.initials: PJ
authors.lastname: Miller
authors.affiliation: Southeast Poultry Research Laboratory, 934 College Station Rd., Athens, GA 30605, USA. Electronic address: claudio.afonso@ars.usda.gov.
authors.forename: Claudio L
authors.initials: CL
authors.lastname: Afonso
mesh_terms: D000818:Animals; D002645:Chickens; D004341:Drug Evaluation; D009521:Newcastle Disease / Q000517:prevention & control*; D009522:Newcastle disease virus / Q000737:chemistry / Q000276:immunology; D014611:Vaccination / Q000379:methods; D014765:Viral Vaccines / Q000737:chemistry / Q000276:immunology / Q000494:pharmacology
chemical_list: D014765:Viral Vaccines
keywords: Homologous vaccination; Mortality; NDV; Newcastle disease; Vaccine efficacy