qRT-PCR was used to determine the mRNA expression of CCL in the liver, confirming that the mRNA expression of CCL4-CCR5 and CCL5-CCR5 increased in the livers of the mice at 6 w after infection; CCL6-CCR2 gradually increased after infection and reached its highest expression at 10 w (Figure 4G). Here, CCL4 is linked to infection.