Induction of early immunopotentiation to fimbriae of Salmonella Enteritidis (SE) by administering thymulin and zinc to SE-vaccinated chicken breeders: Relationship to protection

The purpose of this study is to attempt the induction of early immunopotent iation of antibodies specific to fimbriae of Salmonella enterica serovar En teritidis (SE), by administering thymulin and zinc to SE-vaccinated chicken breeders, and the improvement of protection against a controlled-live chal lenge by SE. The first two groups of breeders were administered subcutaneou sly at 15 and 19 weeks of age a killed SE vaccine. Breeders of the third an d fourth groups were left unvaccinated. Breeders of the first group, immuno potentiated by thymulin and zinc, were able to induce the earliest antibodi es in their pooled sera at 2 weeks post the first SE-vaccination, specific to fimbriae (similar to 21 KDa) of SE. However, the second group that was o nly vaccinated with the same SE-vaccine produced specific antibodies to fim briae at 3 weeks following the second vaccination (22 weeks of age). Breede rs of the third group, that were neither SE-vaccinated nor immunopotentiate d by thymulin and zinc, but were challenged by live SE at 22 weeks of age, were able to show specific antibodies to fimbriae at 3 weeks post challenge (25 weeks of age). The fourth group that was deprived of SE-vaccination, i mmunopotentiators, and challenge didn't show any background antibodies spec ific to SE-fimbriae. The presence of the earliest antibody-immunopotentiati on to fimbriae of SE in breeders of the first group, administered thymulin and zinc, was associated with the lowest frequency of SE-infected ceca (10% ) among the challenged groups. In addition, breeders of the first group wer e the only challenged birds resulting in absence of SE infection in their c ecal tonsils. The first group-vaccinated, immunopotentiated, and challenged , and the second group-vaccinated and challenged only resulted in breeders with absence of SE infection in their oviducts and spleens. In conclusion, immunopotentiation of chicken breeders by thymulin and zinc induces the ear liest specific antibodies to fimbriae of SE associated with the lowest freq uency of SE-infected ceca, and absence of SE infection from cecal tonsils, oviducts and spleens.