However, we noticed that CYP1B1 (Cytochrome P450, Family 1, Subfamily B, Polypeptide 1), which plays a key role in oestrogen metabolism [50], was downregulated after HNhx infection, and this result was consistent with the upregulation of progestin receptor PAQR8 (Figure 11D), which potentially contributes to the negative regulation of anti-PRRSV immunity in vivo as well. Here, CYP1B1 is linked to infection.