Schematic representation of the course of acute HBV infections with resolution. After the infecting event (time 0) follows a lag phase of several weeks without detectable markers. Thereafter HBV DNA (within the virus) and HBsAg increase exponentially in the serum. HBV DNA is detected earlier because its assay is much more sensitive. The peak of HBV DNA and HBsAg is reached before outbreak of the acute disease and both decrease after the onset of clinical symptoms. Initially, the HBV DNA decreases faster because it has a shorter half life time in serum than HBsAg. HBsAg finally disappears whereas HBV DNA may remain detectable in traces. Antibodies against the HBV core antigen (anti-HBc) appear with the onset of symptoms, the protective antibody against HBsAg (anti-HBs) appears very late, usually several weeks or months after disappearance of HBsAg. Disappearance of HBsAg is considered to be a sign of resolution but the virus often remains in occult form in the liver.