Hépatite chronique virale B

Abstract

Chronic infection with the hepatitis B virus (HBV) is estimated to affect 350 millions persons. Chronic hepatitis B is separable into two major forms: the HBe-positive and the HBe Ag-negative. This form of chronic hepatitis B has been shown associated with the selection of replication competent pre-core HBV mutants, that contrary to the wild type HBV, are unable to produce HBeAg. The difference between HBe-Ag-negative chronic hepatitis B and the inactive HBsAg carrier state with negative HBeAg is that in the latter HBsAg positivity and HBeAg negativity combine with : persistently normal ALT levels and low (< 10 5 copies/mL) or undetectable HBV DNA levels. Chronic HBV infection presents three successive phase : in the immunotolerant phase, serum HBeAg was detectable, and serum HBV-DNA levels are high ; serum aminotransferases are normal or minimally elevated. During the second phase, serum HBV-DNA levels decrease and serum aminotransferase levels increase. The non-replicative phase follows HBeAg antiHBe seroconversion. HBV replication is absent. The patients do not have active liver disease. Chronic hepatitis B is defined as chronic inflammatory reaction in the liver continuing without improvement for a least 6 months. Chronic hepatitis is a silent disease. The initial evaluation of patients with chronic HBV infection should include a thorough history and physical examination, with special emphasis on risk factors for coinfection, alcohol use and cirrhosis or liver cancer. Laboratory tests should include assessment of liver disease, markers of HBV replication and tests for coinfection with HCV, HDV and HIV. The purpose of a liver biopsy is to assess the degree of liver damage. Antiviral therapy should be considered in patients with moderate to severe chronic hepatitis if there is active HBV replication (HBV-DNA ≥ 10 5 copies/mL) and persistent elevation of aminotransferases after 3–6 months of observation. Several anti-viral and/or immunomodulatory agents have been evaluated for the treatment of chronic hepatitis B : interferon α, lamivudine and Adefovir. Interferon α had antiviral and immunomodulatory effects, but is associated with many adverse effects. Lamivudine is well tolerated, but, in 16 % of patients, a one-year treatment regim of lamivudine is associated with mutation in the domain of HBV DNA polymerase. Adefovir is a nucleotide analogue with potent anti-viral activity against HBV. Adefovir can be an effective treatment for lamivudine-resistant HBV mutants as well as wild-type HBV.