IL1B and infection: In parallel, infection of TOCs with IBV DMV/1639 resulted in a marked increase in IL1-β mRNA expression at 3, 6, and 12 hpi (Fig. 6A, P < 0.05) and IL-6 mRNA expression at 3 and 6 hpi (Fig. 6B, P < 0.05) compared with both IBV Conn A5968-infected TOCs and non-infected controls (Fig. 6G and H).