This book provides a comprehensive review of the studies concerning HBV epidemiology, pathogenesis and treatment. In addition, it describes recent advances in the knowledge of immune response function, promoting either viral control or persistence, and effects of antiviral therapy in patients with HBV acute or chronic infection are reported. Although mechanisms involved in inflammatory and immune response in acute and chronic HBV infections have been extensively studied, several questions remain unresolved. Moreover, in recent years several key steps in research have contributed to improve our present knowledge of immunopathogenesis of HBV infection.