Enzyme-linked immunoassay of pre-S gene-coded sequences in hepatitis B vaccines

Pre-S gene coded domains of the hepatitis B virus (HBV) envelope protein are highly immunogenic in experimental animals and humans. Their presence in HBV and hepatitis B surface antigen (HBsAg) particles leads to production of anti-pre-S-specific antibodies during the course of HBV infection. Since antibodies specific for pre-S domains are capable of preventing the attachment of HBV to hepatocytes and are virus neutralizing, it would seem desirable to produce HBV vaccines with a standardized level of pre-S determinants to ensure their potential for eliciting the same repertoire of protective antibodies as found after recovery from natural infection. However, a test with appropriate sensitivity for detecting pre-S determinants to ensure their potential for eliciting the same repertoire of protective antibodies as found after (ELISA) for detecting pre-S determinants in vaccines containing ≤ 20 μg of HBsAg. The components of this assay are (1) antibodies to a synthetic peptide pre-S (120-145) adsorbed to polystyrene beads, and (2) β-lactamase-labelled antibodies purified from anti-HBV serum on the basis of their affinity for a pre-S (120-174) β-galactosidase fusion protein produced in Escherichia coli. Results of an evaluation of the pre-S content of HBV vaccines from two different commercial sources are discussed.