Besides, the findings in Fig. 6 show that infection of TOCs with IBV DMV/1639 triggered a robust upregulation of IFN-α and IFN-β mRNA expressions at 3, 6, and 12 hpi, contrasting with the limited responses observed in both IBV Conn A5968-infected TOCs and non-infected controls. This evidence concerns the gene IFNB1 and infection.