Comparative transcriptomic and co-expression analyses of precocious and wild-type Eimeria tenella across...

Precocious strains of Eimeria tenella are widely used as attenuated live vaccines, yet the transcriptional basis of precocious development remains unclear. Here, we established a genetically stable precocious line (PL) with a pre-patent period 12 h shorter than that of the wild-type (WT) strain. Stage-matched RNA sequencing was performed on sporozoites and merozoites (PL at 96 h and 108 h; WT at 108 h and 120 h). Transcriptomic analysis revealed extensive and stage-dependent transcriptional divergence, with the most pronounced differences identified at the sporozoite stage. Notably, 76 invasion-related genes, including those encoding AMA1, MICs, and RONs, were more highly transcribed in PL sporozoites, which were also significantly enriched in functional programs related to protein synthesis, translation, and macromolecule metabolism. As development progressed, transcriptional profiles between PL and WT became more aligned, though differences remained in the coordinated regulation of cytoskeletal organization and microtubule-related genes during early and late merozoite development. Weighted gene co-expression network analysis (WGCNA) and hierarchical clustering further confirmed that precocious development is governed by coordinated, stage-specific gene programs rather than isolated gene-level changes. These findings define the transcriptional landscape underlying accelerated developmental timing in E. tenella and provide a molecular framework for optimizing attenuated vaccines.