Newcastle Disease Vaccination with Beta-Propiolactone-Inactivated Virus Given Intratracheally

Young chickens were vaccinated against Newcastle disease virus (NDV) with inactivated-virus given via the intratracheal route. Variables studied were effect of vaccine adjuvant, age, and immune status of the chickens. Virus was inactivated with betapropiolactone added to infective chicken embryo allantoic fluids. Challenges of immunity were made with 104-5 bird-lethal-dose-50% of homologous virus given intramuscularly. Inactivated virus alone failed to induce immunity in susceptible 1-day-old chickens but induced respective protection levels of 71% and 50% in 7-day-old and 14-day-old chickens. Inactivated virus with adjuvant induced respective protection levels of 96, 100, and 71% in susceptibles that were 1, 7, and 14 days old at vaccination. Passively immune chicks vaccinated at 1 day were not immunized at a level comparable to that of susceptible vaccinates during a 65-day period. Specific hemagglutination-inhibiting antibodies were induced by this method of vaccination.