Of significance to the present study is that the levels of many cytokines (including IL-18, IFNs, TNF-α, IL-4 and TGF-β1) are elevated during hepatitis progression, and have been demonstrated to exhibit antiviral activity in both transgenic mice and cell culture systems [8-10,12,13,24]. The gene discussed is TGFB1; the disease is hepatitis A virus infection.