Title
Epitope-distal effects accompany the binding of two distinct antibodies to hepatitis B virus capsids
Author
Bereszczak, J.Z.
Rose, R.J.
van Duijn, E.
Watts, N.R.
Wingfield, P.T.
Steven, A.C.
Heck, A.J.R.
Publication year
2013
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 α2a 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. © 2013 American Chemical Society.
Subject
Life
QS - Quality & Safety PHS - Pharmacokinetics & Human Studies
EELS - Earth, Environmental and Life Sciences
Biomedical Innovation
Biology
Healthy Living
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DOI
https://doi.org/10.1021/ja402023x
TNO identifier
472005
ISSN
0002-7863
Source
Journal of the American Chemical Society, 135 (17), 6504-6512
Document type
article