The AUTOBIO hepatitis B surface antigen (HBsAg) chemiluminescence immunoassay (CLIA) is intended for the quantitative determination of HBsAg concentration in human serum and plasma.
Hepatitits B is a disease caused by viral infection. The route of infection can be improper needle puncture, blood transfusion or even taking contaminated food or water. Hepatitis B is an immune disease. Invasion of the human body by Hepatitis B virus induces autoimmune reactions, which damage the liver.
Three types of virus-derived particles can be identified in HBV-infected individuals. First, HBV virions or Dane particles, comprising an outer envelope composed of a mixture of glycoproteins, known collectively as HBsAg.This envelope surrounds an inner nucleocapsid made up of the hepatitis B core antigen (HBcAg), which contains the circular partially double-stranded DNA genome. Secondly, spherical particles of nearly 22 nm in diameter and, thirdly, filamentous structures of nearly 20 to 22 nm in diameter and of variable length can also be identified. The spherical and filamentous particles consist of host cell lipid in combination with the virus-derived envelope HBsAg .The particles are found in a 104 to 106 fold excess over the HBV virions, which is why HBsAg has been proven to be such a good marker for hepatitis B infection. The purified 22-nm particles are noninfectious but highly immunogenic, and are the active component of the original hepatitis B vaccine. There are six immunologic markers of HBV: HBsAg, HBcAg, HBeAg and their respective antibodies. The HBsAg however is the first marker to appear in serum. The presence of HBsAg indicates recent infection and if it persists for more than 6 months the patient may become a chronic carrier. The development of serological assays to detect hepatitis B surface antigen (HBsAg) has played a major role in the diagnosis of hepatitis B virus (HBV) infection. With other hepatitis B serological assays, a diagnosis of acute or chronic HBV infection, past infection, or successful vaccination can be determined.
Recent studies showed that there were many clinical applications of quantitative determination of HBsAg concentration in human serum or plasma. Firstly,the quantification of HBsAg provided a means of monitoring the effectiveness of antiviral therapy and detecting the early development of antiviral drug resistance .Secondly,the HBsAg concentration was significantly higher in HBeAg-positive than in HBeAg-negative patients, and there was a significant correlation between the HBsAg concentration and HBV DNA level. After the start of lamivudine therapy, the HBV DNA levels fell rapidly in all patients and so did the serum HBsAg concentrations. Also, in some patients, the increase in HBsAg preceded the increase in HBV DNA.Thirdly,the quantitative determination of HBsAg and anti-HBc/IgM provided additional information, and may be useful in the differential diagnosis of acute and chronic HBV infections and in the follow-up of chronically infected patients. Fourthly, at baseline, the serum HBsAg levels correlated well with the cccDNA. In conclusion, HBsAg quantitation can be a surrogate marker for viral load during the management of chronic HBV infection.
