Epitopes described in "Epitope-distal effects accompany the binding of two distinct antibodies to hepatitis B virus capsids."

Article Authors:Jessica Z Bereszczak; Rebecca J Rose; Esther van Duijn; Norman R Watts; Paul T Wingfield; Alasdair C Steven; Albert J R Heck
Article Title:Epitope-distal effects accompany the binding of two distinct antibodies to hepatitis B virus capsids.
Reference Detail
Reference ID:1025788
Abstract:Infection of humans by hepatitis B virus (HBV) induces the copious production of antibodies directed against the capsid protein (Cp). A large variety of anticapsid antibodies have been identified that differ in their epitopes. These data, and the status of the capsid as a major clinical antigen, motivate studies to achieve a more detailed understanding of their interactions. In this study, we focused on the Fab fragments of two monoclonal antibodies, E1 and 3120. E1 has been shown to bind to the side of outward-protruding spikes whereas 3120 binds to the "floor" region of the capsid, between spikes. We used hydrogen-deuterium exchange coupled to mass spectrometry (HDX-MS) to investigate the effects on HBV capsids of binding these antibodies. Conventionally, capsids loaded with saturating amounts of Fabs would be too massive to be readily amenable to HDX-MS. However, by focusing on the Cp protein, we were able to acquire deuterium uptake profiles covering the entire 149-residue sequence and reveal, in localized detail, changes in H/D exchange rates accompanying antibody binding. We find increased protection of the known E1 and 3120 epitopes on the capsid upon binding and show that regions distant from the epitopes are also affected. In particular, the 2a helix (residues 24-34) and the mobile C-terminus (residues 141-149) become substantially less solvent-exposed. Our data indicate that even at substoichiometric antibody binding an overall increase in the rigidity of the capsid is elicited, as well as a general dampening of its breathing motions.
Affiliations:Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
Reference Type:Literature
PubMed ID:23597076
Journal:J Am Chem Soc
Journal Volume:135
Article Pages:6504-12
Journal ISSN:0002-7863
Article Chemical List:Antibodies, Monoclonal;Capsid Proteins;Epitopes;Hepatitis B Antibodies;Hepatitis B Core Antigens;Immunoglobulin Fab Fragments;Hydrogen;Deuterium
Article MeSH List:Antibodies, Monoclonal(chemistry; immunology); Antigen-Antibody Reactions; Capsid Proteins(immunology); Chromatography, High Pressure Liquid; Crystallography, X-Ray; Deuterium; Epitopes; Hepatitis B Antibodies(immunology); Hepatitis B Core Antigens(immunology); Hepatitis B virus(immunology); Humans; Hydrogen; Immunoglobulin Fab Fragments(immunology); Mass Spectrometry; Models, Molecular; Protein Conformation
Curation Last Updated:2015-06-07 20:25:59