THE USE OF EMBRYONATED CHICKEN EGGS WITH MATERNAL ANTIBODY TO NEWCASTLE DISEASE VIRUS FOR THE PRODUCTION OF LA SOTA STRAIN VIRAL ANTIGEN

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Embryonated eggs from Specific Pathogen Free (SPF) flocks are used ideally in the production of Newcastle disease vaccine. However, in developing countries where SPF flocks are not available, embryonated eggs from healthy chicken flocks are utilized. The present study assessed the use of embryonated eggs having maternal antibodies to Newcastle disease virus (NDV) for the propagation of NDV La Sota vaccine strain. Log, hemagglutination inhibition (HI) antibody titers to NDV in sera of 18 Isa White breeder chickens were determined. Subsequently within one week, 60 eggs were collected from the breeder hens and incubated for 12 days. Maternal antibodies to NDV in the 12-day-old embrayonated eggs were determined from the egg yolk and allantoic fluid. Two fertile eggs each from five hens were then inoculated with 0.1 or 0.2 mL of La Sota vaccine reconstituted in PBS with pH of 7.4 (200 doses/mL). In addition, three eggs from different hens were inoculated with 0.1 mL of the La Sota vaccine. Log: hemagglutination (HA) NDV titers in allantoic fluid were determined from the eggs three days post inoculation. The geometric mean of HI log, antibody titers to NDV detected in sera, yolk and allantoic fluid of eggs were, 7.37, 7.09 and 1.93, respectively. There was no statistically significant difference (p 0.05) between NDV HA log: titers in allantoic fluid harvested following inoculation with 0.1 (between 9 log: to 11 log:) and 0.2 (between 8 log: to 12 log:) mL La Sota vaccine. There was no correlation (r=-0.28) between antibodies to NDV in sera of breeders and the viral titers obtained in allantoic fluid of their embryonated eggs post inoculation with La Sota vaccine. The results of this study indicate that embryonated eggs with maternal antibodies to NDV could be used for propagation of NDV to yield high viral titers. Hence, it is recommended that breeder flocks raised for the purpose of producing eggs intended for NDV vaccine production could be duly vaccinated against field NDV infection.