Structural characterization of viral neutralizing monoclonal antibodies tohepatitis B surface antigen

In this study we describe the viral neutralizing activity of murine monoclo nal antibodies (MAb) specific for hepatitis B surface antigen (HBsAg). This viral neutralizing activity was assessed in vitro by employing Hepatitis D elta Virus (HDV) and human hepatocytes as target cells. To further characte rize these viral neutralizing antibodies we generated a panel of anti-idiot ypic (anti-Id) reagents and serologically characterized these antibodies fo r epitope specificity, Id specificity, and Id heterogeneity. Direct binding and competitive inhibition solid phase enzyme immunoassay have demonstrate d that two murine MAb specific for HBsAg (anti-HBs), designated A1.2 and A3 .1, recognize similar or overlapping epitopes on HBsAg, while monoclonal an ti-HBs, designated A2.1 recognizes a unique HBsAg epitope. Further, Id anal ysis using monoclonal and polyclonal anti-Id reagents have identified both a private and a cross-reactive Id, respectively, on the anti-HBs, A1.2 prep aration. The source of the idiotypic cross-reactivity between A1.2 and A3.1 has been identified, using Western blot analysis, to conformational determ inants expressed by the heavy (H) and light (L) chains of these monoclonal anti-HBs. Lastly, the intrastrain antibody repertoire induced following HBs Ag immunization was found to be relatively restricted in heterogeneity by c lonotype analysis using isoelectric focusing and affinity irnmunoblot analy sis. Interspecies variability in the anti-HBs response was observed based o n epitope recognition using purified anti-HBs from a variety of species. (C ) 1999 Elsevier Science Ltd. All rights reserved.