ERVW-1 and infection: Furthermore, we investigated the mRNA expression level of ALV-J-related genes after miR-34b-5p overexpressed in DF-1 cells; the mRNA expression level of Env (Supplementary Figure 1C), Gag (Supplementary Figure 1D) and Pol (Supplementary Figure 1E) were upregulated in ALV-J-infected DF-1 cells compared with that in NC group at 2–48 h ALV-J infection time points.