CXCL8 and infection: For example, He et al. found TLR3, IL-8, and IFNβ expression were more up-regulated in response to the vvIBDV strain than a vaccine strain, and Liu et al. found elevated expression of cytokines following vvIBDV infection compared to a vaccine strain, however the vv strain replicated to significantly higher titers that the vaccine strains in both studies, making comparison of gene expression changes challenging (Liu et al., 2010; He et al., 2017).