Interaction of Lentogenic Newcastle Disease Virus and Specific Antibodies within the Yolk Sac

Abstract

SUMMARY Log dilutions of F strain Newcastle disease virus (NDV) were inoculated into the yolk sacs of fertile eggs from hens immune to NDV. The virus was examined by hemagglutination (HA) test, and mean embryo infective dose (EID50) titration by the allantoic sac route. Embryopathogenicity of the virus was lower by the yolk sac route. Serum NDV hemagglutination-inhibition (HI) titers were significantly lower in chicks hatched from eggs which received 10-1 to 10-3 log dilutions of NDV than in groups which received 10-4 to 10-10 log dilutions of NDV and an uninoculated control group. Three groups of fertile eggs from hens immune to NDV were inoculated into the yolk sac with formaldehyde-inactivated F strain NDV, uninactivated virus and formaldehyde-treated nutrient broth, respectively; a fourth group was left uninoculated. Virus was examined before inactivation by HA and EIDso titrations, and after inactivation by HA test and infectivity to fertile eggs by the allantoic sac route. No chicks hatched from eggs that received live virus. NDV HI titers were significantly lower in the group which hatched from eggs inoculated with inactivated virus than in the nutrientbroth-inoculated and uninoculated groups.