Preparation of a dane core (hepatitis B) antigen from human plasma.

Hepatitis B surface antigen (HBsAg) positive plasma, obtained from blood donors, was used to prepare an antigen (HBcAg) from the inner core of the Dane particle, the larger of the two spherical particles found in the blood in hepatitis B infection. The antigen was prepared by a series of centrifugation procedures on caesium chloride and sucrose gradients. Dane particle-rich fractions obtained from these gradients and concentrated by centrifugation were treated with Tween 80 to remove the outer coats from the particles. The remaining Dane particle cores were recovered by velocity sedimentation on a sucrose gradient. Preparations containing the Dane cores were used as antigens in the immune electron microscopy and complement fixation tests to demonstrate the specificity of HBcAg and lack of fross relationship with HBsAg. HBcAg will be used for the study of hepatitis B infections in man.