Similarly, analysis of IL-6 at the transcriptional level by Northern blot showed induction of IL-6 mRNA in both cell clones infected with IBV at 8 (Fig. 6d, lanes 1 and 5), 12 (Fig. 6d, lanes 2 and 6), 16 (Fig. 6d, lanes 3 and 7) and 24 (Fig. 6d, lanes 4 and 8) hours post-infection, respectively. Here, IL6 is linked to infection.