Two experimental approaches were used to investigate the immunological responses of chickens to a commercial killed Salmonella enteritidis (SE) vaccine. In the first, the effects of host age on antigen-specific proliferative responses and cytokine production were examined. Compared with non-vaccinated controls, 4-wk-old vaccinated chickens showed higher proliferation to SE LPS and flagella. The lymphoproliferation responses to these antigens of 8-mo-old vaccinated chickens were not different compared to the non-vaccinated controls. Increased production of interferon-γ (IFN-γ) and interleukin-2 (IL-2) by antigen-stimulated splenocytes following vaccination were, in general, more often observed in 4-wk-old compared with 8-mo-old chickens, whereas serum levels of these cytokines were consistently higher in the vaccinated birds compared with controls regardless of age. The second set of experiments were designed to determine the effects of SE vaccination on mitogen- or antigen-induced splenocyte proliferation and serum nitric oxide (NO) and cytokine levels. Splenocytes from vaccinated chickens stimulated with SE flagella showed significantly increased numbers of TCRγδ + cells at 7 days post-vaccination compared with non-vaccinated birds. In contrast, no differences were noted with CD4 + , CD8 + , or TCRαβ + cells at any time points examined. Higher levels of NO production were observed following stimulation with SE flagella at 4, 7, 11, and 14 days after SE vaccination while serum levels of IFN-γ, IL-1, IL-6, and IL-8 were elevated only at day 7 post-vaccination. In conclusion, younger chickens mounted a more robust antigen-specific immune response to the SE vaccine compared with older birds and vaccination induced not only T-cell-mediated responses but also host innate and pro-inflammatory responses.
Deux approches experimentales ont ete utilisees pour examiner les reactions immunologiques de poulets au vaccin tue commercial Salmonella enteritidis. La premiere visait a observer les effets de l'age du sujet sur les reactions proliferatives specifiques aux antigenes et la production de cytokine. Par comparaison avec des temoins non vaccines, les poulets de 4 semaines vaccines ont montre un taux superieur de proliferation de LPS et flagelles de SE. Les reactions de lymphoproliferation a ces antigenes chez des poulets vaccines ages de 8 mois n'etaient pas differentes de celles de temoins non vaccines. On a en general observe l'augmentation de la production d'interferone-γ (IFN-γ) et d'interleukine-2 (IL-2) par des splenocytes stimules par des antigenes a la suite de la vaccination plus souvent chez des poulets de 4 semaines que chez des poulets de 8 mois, tandis que les niveaux de serum de ces cytokines etaient regulierement plus eleves chez les volatiles vaccines que chez les temoins non vaccines, quel que soit leur age.La seconde serie d'experiences etait concue pour determiner les effets de la vaccination SE sur la proliferation de splenocytes causee par des mitogenes ou des antigenes, et sur les niveaux d'oxyde nitrique (NO) et de cytokine. Les splenocytes de poulets vaccines stimules avec flagelles SE montraient des taux de cellules TCRγδ + beaucoup plus eleves a 7 jours apres la vaccination que ceux de volatiles non vaccines. Des taux de production de NO superieurs etaient observables a la suite d'une stimulation avec flagelle SE a 4, 7, 11 et 14 jours apres vaccination SE tandis que les niveaux de IFN-γ, IL-1, IL-6, et IL-8 n'etaient superieurs qu'au 7eme jour apres la vaccination. En conclusion, des poulets plus jeunes ont temoigne d'une reponse immunitaire specifique aux antigenes au vaccin SE plus forte que celle de volatiles plus ages, et la vaccination a produit non seulement des reponses mediatisees par les cellules T mais aussi des reponses innees et pro-inflammatoires chez les sujets.