Serum marker indicating active viral replication in hepatitis-B is: September 2006, March 2013
Ans. B: HBeAg, D: HBV DNA The first detectable viral marker for hepatitis-B is HBeAg, followed by hepatitis B, e-antigen (HBeAg) and HBV DNA. Titers may be high during the incubation period, but HBV DNA and HBeAg levels begin to fall at the onset of illness and may be undetectable at the time of peak clinical illness. Core-antigen does not appear in blood, but antibody to this antigen (anti-HBc) is detectable with the onset of clinical symptoms. The immunoglobulin M (IgM) fraction is used in an impoant diagnostic assay for acute hepatitis B, infection. Before current molecular assays were available, it was the only marker detectable in the window period, the time between the disappearance of HBsAg and the appearance of anti-HBs. Patients who clear the virus lose HBsAg and develop anti-HBsAb, a long-lasting antibody associated with immunity. The presence of anti-HBsAb and anti-HBcAb (IgG) indicates recovery and immunity in a previously infected individual, whereas a successful vaccination response produces antibody only to HBsAg. HBeAg is another viral marker detectable in blood and correlates with active viral replication and therefore high viral load and infectivity. The-antigen is synthesized from a strand of DNA immediately preceding the area that codes for the core-antigen.
HBsAg
HBeAg
HBcAg
HBV DNA