Humoral and cellular immunity in guinea pigs to polypeptides derived from HBsAg-containing particles

Abstract

Recent studies in this laboratory have shown that purified HBsAg contains at least 7-9 polypeptide subunits ranging in molecular weight (MW) from 18,000 to 120,000; at least three of these are associated with carbohydrates. In addition, two glycosphingolipids have been extracted which are structurally similar to the blood group antigenic substance. The glycoproteins and glycolipids are of particular interest since it has been reported that carbohydrate is associated with the antigenic activity of HBsAg. Antisera to these subunits have been produced in guinea pigs. These results stimulated further 'in vivo' investigations into the possible development of a subunit vaccine which would exclude genes of a viral or cellular nature and would not be infectious. Guinea pigs were immunized with HBsAg, subtypes adw and ayw, and with two polypeptides (40,000 MW and 24,000 MW) in complete Freund's adjuvant. Control animals were inoculated with normal human serum or with polyacrylamide gel. Animals were boostered on day 14 and tested on day 30 for the development of cell-mediated immunity (CMI) by the macrophage inhibition assay, and for humoral immunity by PHA and RIA. Migration of peritoneal exudate (PE) cells was inhibited 30-88% in guinea pigs immunized with the 40,000-MW polypeptide when challenged with purified HGsAg, subtype adw or ayw, or with the 40,000-MW preparation, but the results were inconclusive with the 24,000-MW subunit. Similar evidence of CMI was observed with PE cells derived from guinea pigs inoculated with purified subtype-specific HBsAg or with the 24,000-MW polypeptide. Humoral responses were predictable, and showed a reasonable degree of correlation with the CMI response. Control animals failed to respond to challenge with purified preparations of HBsAg or the 40,000-MW polypeptide, but did show CMI with their respective immunogens and - in the case of guinea pigs inoculated with normal human serum - with the 24,000-MW subunit, suggesting that the latter may contain an antigenic determinant related to a human serum protein.