Zoledronate-induced activation of γδ T cells is associated with NK cell activation and reduced parasite burden in the cecum of Eimeria tenella-infected chicks.

This study aimed to elucidate the role of γδ T cells in chicks infected with Eimeria tenella. Zoledronate was administered in vivo to activate γδ T cells. White Leghorn chicks were divided into four groups: zoledronate-treated (ZOL), infected control (CT), uninfected zoledronate-treated (UN/ZOL), and uninfected control (UN). Chicks in the CT and ZOL groups were orally inoculated with sporulated E. tenella oocysts (1 × 10^4 oocysts/chick) at 14 days of age. Fecal samples were collected between 4 and 15 days post-infection (dpi) to assess oocyst shedding. Cecal samples were obtained at 5 dpi for histopathological examination and gene expression analysis. Lesion and parasite burden scores were significantly reduced in the ZOL group compared with the CT group. Expression levels of IL-17 A, IL-21, and IFN-γ were significantly higher in the ZOL group, whereas IL-13 and PGES expression was significantly higher in the CT group. These findings indicate that activation of γδ T cells alleviates cecal tissue damage caused by E. tenella infection. Moreover, they suggest that NK cells activated by IL-21 may play a role in parasite control and contribute to the establishment of the local immune environment, but the effect of parasite control by IL-21-induced NK cell activation requires further research. Future studies should also explore whether γδ T cell activation and IL-21-mediated immunity are associated with mechanisms of parasite control.