Use of inoculated eggs as a vehicle for the oral rabies vaccination of red foxes (Vulpes fulva).

The ERA vaccine strain of rabies virus propagated on continuous porcine kidney tissue culture cells (PK15) was inoculated into the yolk sac of embryonated chicken eggs for the purpose of oral vaccine distribution. Two inoculated eggs were subsequently fed to each of 12 serologically rabies-negative foxes. Six (50%) of the foxes developed demonstrable rabies serum-neutralizing antibody within 4 weeks of vaccination and resisted challenge to street virus 14 weeks postvaccination. Testing of inoculated eggs for virus stability in the presence and absence of a casein hydrolysate-sucrose stabilizer at 6, 22, and 37 C for up to 15 days revealed no advantage to the stabilizer-vaccine mixture in eggs.