n HBV: Hepatitis B virus.
n HBsAg:   Hepatitis B surface antigen. Marker of infectivity
when found in serum.
n anti-HBs: Antibody to HBsAg. Marker of immunity when
found in serum.
n HBcAg: Hepatitis B core antigen. No commercial test
available for this.
n anti-HBc: Antibody HBcAg. Marker of past or current
infection.