Heterogeneity of hepatitis B surface antigen-associated particles isolated from chimpanzee plasma

Hepatitis B surface antigen (HBsAg) was purified from approximately 8 liters of pooled plasma from a carrier chimpanzee. Precipitation of HBsAg with polyethylene glycol resulted in more than 20-fold purification, with about 80% recovery of antigenic activity. The sample was separated by further purification and fractionation into three populations of HBsAg-associated particles by column chromatography on hydroxylapatite: the first contained short filaments and 22- to 28-nm spheres, the second was composed of larger filaments and variable-sized spheres, and the third contained mostly 16- to 22-nm spherical particles. A large volume of the polyethylene glycol precipitate passed through hydroxyl-apatite twice yielded over 650 mg of partially purified HBsAg. A pooled preparation of purified HBsAg was separated by zone-convection electrofocusing into five peaks of antigenic activity within the pH range of 4.7 to 5.7.