Hepatitis B and C treatment: New perspectives

Extract: Hepatitis B and C viruses are structurally unrelated viruses that cause a major burden to health throughout the world. It is estimated that there are 350 million carriers of hepatitis B and 170 million carriers of hepatitis C worldwide. Both may cause hepatitis with the eventual risks of cirrhosis and primary liver cancer (hepatocellular carcinoma, HCC). Until recently, very few therapeutic options were available to afflicted patients. Several new significant advances have now been made in assessing and treating infected patients and ongoing studies are now targeting more challenging patient groups who have failed to respond to previous treatments or who have associated co-morbidities. Hepatitis B virus (HBV) is a DNA virus that is spread sexually, vertically (mother-to-baby) and via blood products. The structure of the virus includes the hepatitis B surface antigen (HBsAg) that originates from the viral envelope and the hepatitis B e antigen (HBeAg) that is released from the nucleocapsid (virus coat and genome). HBsAg is present in the blood circulation during active infection and chronic hepatitis B is diagnosed if HBsAg is persistent beyond 6 months. HBeAg is present when the virus is actively replicating and is associated with high levels of HBV DNA and an increased risk of progression to cirrhosis and HCC. Recently, a form of virus has been identified called the precore mutant in which high levels of HBV DNA may be present in the absence of eAg due to a mutation in the gene encoding eAg or its upstream regulatory gene. Patients with high levels of HBV DNA and HBeAg are also at a high risk of liver disease.