IFNA1 and chronic hepatitis B virus infection: Furthermore, alpha interferon (IFN-α) is approved by administrative authorities for treatment of chronic hepatitis B. Pegylated IFN-α is effective in achieving a sustained virological response, which is defined by hepatitis e antigen (HBeAg) seroconversion and/or HBV DNA levels below 20,000 copies/ml at 6 months after completion of the therapy, in about 30% of HBeAg-positive and 40% of HBeAg-negative cases [25]–[27].