MYD88 and infection: We observed that at 3 days post-infection, Y. ruckeri infection caused an up-regulation of the expression of anti-inflammatory cytokines IL-10 and MYD88 (p < 0.01, respectively); however, there were no significant differences in the expression levels of the cytokine IL-10 among treatments when compared to the No PACAP control (p > 0.05) (Figure 8A).