The avirulent Salmonella typhimurium chi3985 was used to vaccinate white leghorn chickens at 16 and 18 weeks of age, and the effect of maternal antibody on Salmonella colonization of progeny of vaccinated hens was assessed with S. typhimurium F98 or chi3985. Progeny of hens that had been vaccinated at 1 and 3 or 2 and 4 weeks of age with chi3985 were used to determine the effect of maternal immunity on
vaccine efficacy. Vaccination of hens induced long-lasting Salmonella-specific
antibodies which were transferred into eggs and were detected as
immunoglobulin G (
IgG) in the egg yolk. Maternal antibody was detected in the progeny of vaccinated birds as
IgG and
IgA in serum and intestinal fluid, respectively. The titer of maternally transmitted
IgG or
IgA was highest in the first week of life of the progeny and declined with age. Maternal
antibodies prevented colonization of the chicks by S. typhimurium chi3985 and reduced colonization by S. typhimurium F98. Overall, chicks from vaccinated hens had significantly higher antibody responses than did the progeny of nonvaccinated hens after oral
infection with Salmonella strains. Maternal antibody reduced the efficacy of vaccination of progeny with chi3985 at 1 and 3 weeks of age. But vaccination at 2 and 4 weeks of age induced excellent protection against challenge with S. typhimurium F98 or S. enteritidis 27A PT 8 in birds from vaccinated hens and in specific-pathogen-free chickens. Vaccination of chickens at 2 and 4 weeks of age has been shown to protect the birds against challenge with homologous and heterologous Salmonella serotypes. A combination of vaccination of adult animals and use of the progeny of vaccinated birds will enhance effective control of
Salmonella infections in the poultry industry. This will
complement the present control of Salmonella-associated
food poisoning caused by Salmonella enteritidis in eggs because the avirulent S. typhimurium
vaccine strain chi3985 induced excellent protection against S. enteritidis in chickens.