title: The role of quantitative hepatitis B surface antigen revisited.
abstract: In the past 10years, there has been a lot of enthusiasm surrounding the use of serum hepatitis B surface antigen (HBsAg) quantification to predict disease activity and monitor treatment response in chronic hepatitis B. The measurement of HBsAg levels have been standardized in IU/ml, and nowadays it is almost a mandatory measurement due to the development of new antiviral treatments aiming at HBsAg seroclearance, i.e., functional cure of hepatitis B. Recently, there has been an improved understanding of the molecular virology of HBsAg, and particularly the relative roles of covalently closed circular DNA and integrated hepatitis B virus (HBV) DNA. This has shed new light on the interpretation of HBsAg levels in different phases of chronic hepatitis B. HBsAg level can assist the differentiation of immune tolerance and immune clearance in hepatitis B e antigen (HBeAg)-positive patients, and it can predict inactive disease and spontaneous HBsAg seroclearance in HBeAg-negative patients. The determination of HBsAg level is pivotal to individualize pegylated interferon (PegIFN) treatment; it is the key investigation to decide early termination of PegIFN among non-responders. Among patients treated by nucleos(t)ide analogues, responders tend to have dramatic reduction of HBsAg to low levels, which may be followed by HBsAg seroclearance. With newer data on combination treatment of PegIFN and nucleos(t)ide analogues as well as emerging new antiviral agents, HBsAg quantification is expected to become increasingly important to monitor and guide antiviral therapy for chronic hepatitis B.
authors: Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, German Center for Infection Research (DZIF), Partner Site Hannover-Braunschweig, Germany.
authors: Markus
authors: M
authors: Cornberg
authors: Department of Medicine and Therapeutics, Institute of Digestive Disease and State Key Laboratory of Digestive Disease, The Chinese University of Hong Kong, Hong Kong.
authors: Vincent Wai-Sun
authors: VW
authors: Wong
authors: Victorian Infectious Diseases Reference Laboratory (VIDRL), Doherty Institute for Infection and Immunity, Melbourne, Australia.
authors: Stephen
authors: S
authors: Locarnini
authors: Hepatology Unit and Laboratory of Molecular Genetics and Pathology of Hepatitis Viruses, Reference Center of the Tuscany Region for Chronic Liver Disease and Cancer, University Hospital of Pisa, Italy.
authors: Maurizia
authors: M
authors: Brunetto
authors: Toronto Center for Liver Disease, Toronto General Hospital, University Health Network, Toronto, Canada.
authors: Harry L A
authors: HLA
authors: Janssen
authors: Department of Medicine and Therapeutics, Institute of Digestive Disease and State Key Laboratory of Digestive Disease, The Chinese University of Hong Kong, Hong Kong. Electronic address: hlychan@cuhk.edu.hk.
authors: Henry Lik-Yuen
authors: HL
authors: Chan
mesh_terms: D019468:Disease Management; D006514:Hepatitis B Surface Antigens / Q000032:analysis*; D006513:Hepatitis B e Antigens / Q000032:analysis*; D006515:Hepatitis B virus / Q000502:physiology*; D019694:Hepatitis B, Chronic / Q000276:immunology / Q000821:virology; D006801:Humans; D012698:Serologic Tests / Q000379:methods
chemical_list: D006514:Hepatitis B Surface Antigens; D006513:Hepatitis B e Antigens
keywords: Antiviral treatment; Entecavir; HBsAg; Hepatitis B; Pegylated interferon; Tenofovir