IL1B and infection: The IL-1β mRNA expression level in group IV and group III between day 1 and 3 post-infection were lower (p < 0.01) compared with the expression level of IL-1β mRNA in group I. Group IV showed a lower IL-1β mRNA expression level compared with group I (p < 0.001) and group II (p < 0.01) at day 5–7 post-infection (Figure 8A).