Increased caecal Intestinimonas abundance inhibits E. tenella gametogenesis via EtGFAT regulation and alleviates infection through immunity.

Abstract

BACKGROUND: Chicken coccidiosis caused by Eimeria tenella (E. tenella) poses a major threat to global poultry production, with its tropism for the caecal microenvironment and dynamic interactions with the resident microbiota remaining incompletely understood. The caecal microbiota plays a critical role in host‒parasite interplay, yet the mechanisms through which microbial homeostasis influences E. tenella development and host resistance remain elusive. This study aimed to elucidate the causal relationship between caecal dysbiosis and E. tenella pathogenesis, with a focus on identifying microbiota-derived regulators of parasite development and host immunity. RESULTS: Antibiotic-induced caecal dysbiosis (ABX) significantly impaired E. tenella macrogametogenesis, demonstrating microbiota-dependent regulation of parasitic development. Faecal microbiota transplantation (FMT) validated this causal link, revealing that microbial reconstitution restored parasite maturation. Notably, Intestinimonas spp. were identified as key inhibitors of E. tenella development through transcriptional regulation of the EtGFAT gene (Eimeria tenella glucosamine: fructose-6-phosphate aminotransferase), a critical mediator of macrogamete formation. Furthermore, the transplantation of Intestinimonas butyriciproducens (I. butyriciproducens) attenuated clinical manifestations of infection while increasing IFN-γ secretion from CD8T lymphocytes, thereby enhancing host resistance to E. tenella. CONCLUSIONS: 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. The dual role of I. butyriciproducens in suppressing parasitic virulence and potentiating adaptive immune responses underscores the therapeutic potential of microbiota-targeted strategies. These findings provide a foundation for the development of novel anticoccidial interventions through targeted manipulation of caecal microbial communities. Video Abstract.