Viscerotropic Velogenic Newcastle Disease in Turkeys: Immune Response Following Vaccination with Either Viable B 1 Strain or Inactivated Vaccine

Abstract

When used as a vaccine, live letogenic B1 Newcastle disease virus (NDV) protects turkeys against challenge-exposure to viscerotropic velogenic NDV (VVNDV). Low-level passively-immune poults were vaccinated one, two, or three times at various intervals and their immunity challenged at various times from 1 to 10 months of age. Newcastle disease virus was isolated readily from either the blood, trachea, or vent of turkeys in all challenge groups (through 5 months of age) on the 3rd to 6th days postchallenge (PC) but after 14 days PC was isolated rarely. Virus was isolated from turkeys that had high titers of serum hemagglutination-inhibition antibodies at the time of challenge. The anamnestic antibody response appeared to be stronger in poults that had low antibody titers prior to challenge-exposure to VVNDV. In a small-scale study with an inactivated VVNDV vaccine, vaccinated poults were protected against challenge with the homologous viscerotropic virus. Parallel control studies on the infectivity of viscerotropic NDV for turkeys indicated that resistance to VVNDV increased with age.

Comparative Evaluation of the Protective Efficacy of Different Vaccination Programs Against a Virulent Field Strain of the Newcastle Disease Virus in Broilers

“…The virus is highly transmissible in poultry with low antibody titers (Boven et al, 2008). There have been several panzootics of this serious disease in poultry during the last four decades (Alexander, 2011) and the velogenic strains are now endemic in the commercial poultry farms of many countries (Boney et al, 1975, Giambrone & Closser, 1990, including Iran.…”