IDENTIFICATION OF HEPATITIS-B VIRUS CORE PROTEIN REGIONS EXPOSED OR INTERNALIZED AT THE SURFACE OF HBCAG PARTICLES BY SCANNING WITH MONOCLONAL-ANTIBODIES

Hepatitis B virus (HBV) core antigen (HBcAg) particles purified from E scherichia coli were probed in a competition enzyme immunoassay (EIA) with a panel of 16 murine monoclonal antibodies (MAbs) directed to dif ferent forms of core protein. The linear binding sites of the MAbs wer e mapped by combination of solid-phase and competition EIA using synth etic peptides covering the complete sequence of HBV core protein. Rela tive accessibilities of the linear binding sites at the HBcAg surface were investigated by comparing reactivities in solution of the MAbs to (i) two genetic variants of particulate HBcAg, (ii) denatured core pr otein, and (iii) synthetic peptides mimicking the appropriate linear b inding sites. Further, accessibilities of HBV preS1 and preS2 epitopes (introduced into core protein at positions 77 or 144) at the surface of chimeric HBcAg particles were investigated. The previously describe d surface localization of core protein region 78-83 at the core partic le surface was confirmed. In addition, another region, encompassing re sidues 127-133, was found to occupy a surface position at particulate HBcAg, whereas regions 9-20 and 133-145 were exposed after denaturatio n of the core protein and at synthetic peptides but not at particulate HBcAg. (C) 1994 Academic Press, Inc.