TGFB1 and Hepatic fibrosis: HHV-6A infection also induced the strong downregulation of miR-20 (up to 2458 fold at 4 and 10 d.p.i.), which was recently recognized as a key factor in liver fibrosis, since its down-regulation resulted in TGFBR2-activated TGF-β signaling pathway, followed by the activation of macrophage and extracellular matrix (ECM) production [92].