Hepatitis B Virus   

   Dr Snehalata Pattnaik
   Dr Manorama swain
   Cuttack

  Under the electron microscope Hepatitis B virus is a double walled spherical structure of 42 nm (nanometer) in diameter. Of these double walls, the outer wall represents the core particle or 'c' antigen and the inner wall represents the 'e' antigen. It has an outer surface coat of particles measuring 22 nm, which is known as the surface antigen or 'Australia Antigen'. Hepatitis B virus is a DNA virus containing double stranded DNA and an enzyme called DNA dependent DNA polymerase. The Hepatitis B virus particle is also known as 'Dane particle'. The virus only replicates in the liver and there is evidence to suggest that it becomes integrated with the host nuclear protein. This integration may be an important link in the development of hepatoma or 'liver cancer'. HbsAg or, Hepatitis B surface Antigen or Australia Antigen was discovered by the Nobel Laurate Baruch S. Blumberg in 1963. It has different antigenic subdeterminants. They are a, d, y, w and r. Combinations of these subdeterminants are useful in epidemiology for studying geographical differences. Screening of Hepatitis B surface Antigen or HBsAg in the blood    serves as a definite tool for the detection of the presence of Hepatitis B virus in the body.  Besides, diagnosis of the antigenic subdeterminant is also important because the different subtypes respond to treatment in a different ways and hence this is important from prognostic view point also.The virus infects the host through parenteral route and produces the diseases like acute hepatitis, chronic hepatitis, fulminant hepatitis, cirrhosis and hepatocellular carcinoma.  Hepatitis B can be easily prevented by vaccination.

  Hepatitis B vaccine :

   In 1969 Blumberg and Irvin Millman invented the first hepatitis B vaccine. The vaccine is administered as follows in three dosages. First dose to start any day. Second dose after one month of first dose and the third dose after six months of first dose. One ml. vaccine is given intramuscularly to adult where as 0.5 ml. is given to children. The best way to administer the vaccine is at birth.