Detection of antibodies to pre-S2 encoded epitopes of hepatitis B virus by monoclonal antibody-enzyme immunoassay.

An inhibition enzyme immunoassay (IEIA) for the detection of anti-pre-S2 antibody has been developed and used to evaluate anti-pre-S2 responses in the sera of patients recovering from acute type B hepatitis and in the sera of healthy recipients of HBV vaccine. In the assay, we used two monoclonal antibodies recognizing the nonoverlapping epitopes (pre-S2a and pre-S2b) of the pre-S2 protein of HBV envelope which compete with human anti-pre-S2 for the limited antibody-binding sites on recombinant HBsAg particles (pre-S and S gene product). Two variants of the method were assayed employing the reference pre-S2 antigen on the solid (IEIA-sp) or in the liquid phase (IEIA-lp). Two McAbs were used to detect antibodies reacting specifically with pre-S2a and pre-S2b epitopes of the pre-S2 sequence. Both variants gave similar results and were successfully used for the determination of anti-pre-s2 in sera. We demonstrated that during HBV infection as well as after vaccination against HBV both pre-S2 epitopes generate specific immune responses. Anti-pre-S2 were detected in 45.3% patients recovering from HBV infection and in 43.7% of healthy recipients of the HBV vaccine licensed in France. Anti-pre-S2a and anti-pre-S2b were detected in sera in dilutions up to 10(-5). IEIA may provide a specific and highly sensitive screening test for monitoring serum anti-pre-S2 levels during HBV infection and after immunization with HBV vaccine.