CD8A and infection: Furthermore, the transplantation of Intestinimonas butyriciproducens (I. butyriciproducens) attenuated clinical manifestations of infection while increasing IFN-γ secretion from CD8<sup>+</sup> T lymphocytes, thereby enhancing host resistance to E. tenella.<h4>Conclusions</h4>This study revealed that caecal microbiota homeostasis is indispensable for E. tenella developmental progression and highlights Intestinimonas as a pivotal microbial regulator of parasite biology.