CIITA and viral infectious disease: Initial findings indicate that CHS significantly modulates a range of physiological aspects in CVds through pivotal genes including TLR7, IGF1, MAP3K1, CIITA, LCP2, PRKCB, and PLCB2. Notably, TLR7, highly expressed in duck lung tissue, is a key gene in the innate immune defense against viral infections such as influenza (78–80), and also plays a role in egg production (79–83).