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Characterization of the reactivity pattern of murine monoclonal antibodies against wild‐type hepatitis B surface antigen to g145r and other naturally occurring “a” loop escape mutations
Author(s) -
Cooreman Michel P.,
van Roosmalen Mark H.,
te Morsche René,
Sünnen Cécile M. G.,
Schoondermarkvan de Ven Esther M. E.,
Jansen Jan B. M. J.,
Tytgat Guido N. J.,
de Wit Pauline L. M.,
Paulij Wilma P.
Publication year - 1999
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1002/hep.510300508
Subject(s) - virology , monoclonal antibody , antigen , antibody , reactivity (psychology) , loop (graph theory) , chemistry , biology , microbiology and biotechnology , immunology , medicine , pathology , alternative medicine , mathematics , combinatorics
The hepatitis B surface antigen (HBsAg) “a” domain harbors major B‐cell epitopes. Viruses with mutations in this region emerge after vaccination or during hepatitis B immune globulin (HBIg) prophylaxis. A strain with G145R replacement has been almost invariably isolated as a major escape mutant. We investigated mutant antigen‐antibody interactions with direct binding assays. G145R and 16 other naturally occurring recombinant HBsAg mutants were expressed in mammalian Cos‐1 cells. The reactivity of a panel of 28 murine anti‐hepatitis B surface antigen (anti‐HBs) monoclonal antibodies to mutant antigens was measured with enzyme immunoassay and expressed as percentage compared with the wild‐type (wt) HBsAg signal for each antibody. All point‐mutated proteins displayed diffuse intracellular immunofluorescent labeling corresponding to a secretory pathway. Monoclonal antibodies (mAbs) were classified according to different binding patterns. The effect of mutations on antibody binding differs depending on the amino acid involved and on the location within the “a” loop. As expected, most antibodies had absent or negligible binding (<40%), notably with residue 145 replacements. However, we identified antibodies that reacted with conformational epitopes but nevertheless had adequate reactivity (>40%) with all mutant antigens, including G145R. The effect of G145R was more pronounced than that of G145A. A subgroup of antibodies had substantially increased recognition (>120%) of antigens with mutations in the first loop. We demonstrated that antibodies can be selected or combined that react with all mutants investigated, including G145R. These data offer perspectives for improving anti‐HBs–based protection against hepatitis B.