IFNB1 and infection: Infection of TOCs with IBV DMV/1639 led to a significant increase in IFN-α and IFN-β mRNA expressions at 3, 6, and 12 hpi (Fig. 6A and B, P < 0.05) compared with both IBV DMV/1639-infected TOCs and non-infected controls (Fig. 6A and B).