Toward a Safer Live Vaccine: Targeting the Key Gene EtMob1 to Block Sporogony in Eimeria tenella

Avian coccidiosis, caused by Eimeria species, is a major parasitic disease causing severe economic losses in poultry. Sporogony, the process by which non-infectious oocysts become infectious, is a key target for transmission-blocking vaccines. Mob1, a core Hippo pathway component regulating the cell cycle, cytokinesis, and microtubule homeostasis, is highly expressed during Eimeria tenella sporogony, but its role in apicomplexan parasites remains unclear. Here, we characterized EtMob1’s molecular features, sporogony expression pattern, and biological functions, and evaluated a EtMob1-deficient strain as a vaccine candidate. EtMob1 belongs to the Mob1/phocein superfamily, is highly conserved among apicomplexans, and localizes to the nucleus with peak expression during early sporogony (5–12 h). Using CRISPR/Cas9 and an IAA-inducible degradation system, we generated a conditional knockdown strain. EtMob1 deletion significantly reduced pathogenicity, alleviated cecal lesions, decreased oocyst shedding, and conferred immune protection in chickens. Transcriptomic analysis showed that EtMob1 knockdown caused widespread downregulation of motor protein genes at early sporogony (8 h), and at late stage (48 h), a compensatory upregulation of motor protein genes alongside significant downregulation of ribosomal protein genes. This suggests EtMob1 regulates sporogony by coordinating cytoskeletal dynamics and protein synthesis homeostasis. Collectively, our study identifies EtMob1 as a key determinant of Eimeria pathogenicity and provides a molecular target for understanding sporogony regulation and developing novel transmission-blocking vaccines against coccidiosis.