Comprehensive Analysis of Immune Response and Transcriptome Profiling Reveals the Molecular Basis Underlying Breed-Specific Responses to Eimeria tenella Infection in Chickens with Differing Susceptibility Levels

Wenchang Chickens (WCCs) and Recessive White Feather Chickens (RWFCs) are two important broiler breeds in China, although their susceptibility to <i>E. tenella</i> has not been compared. This study explores these differences in susceptibility. The results showed that WCCs exhibited lower susceptibility, as evidenced by no mortality and significantly reduced oocyst production compared to RWFCs. Additionally, WCCs had higher levels of CD3⁺CD4⁺ T lymphocytes and lower levels of CD3⁺CD8α⁺ T lymphocytes, both before and after infection, compared to RWFCs. Notably, serum IgA and IgG antibody levels in WCCs were significantly higher than those in RWFCs. RNA-seq analysis at 2, 4, and 7 days post-infection (dpi) revealed a consistent upward trend in gene expression in WCCs, while RWFCs exhibited a fluctuating pattern. Functional analysis indicated that the stable immune response, as annotated by the differentially expressed genes (DEGs) in WCCs, along with distinct metabolic alterations, may contribute to their enhanced resistance. Several hub genes, including SLC7A11, CCL19, CD4, HSPA5, and HSP90AA1, were identified within gene interaction networks specific to each breed. These findings provide valuable insights into the molecular mechanisms underlying the differential susceptibility of WCCs and RWFCs, offering potential targets for new coccidiosis control strategies.