TY - JOUR
T1 - Cryo-EM study of Hepatitis B virus core antigen capsids decorated with antibodies from a human patient
AU - Kandiah, Eaazhisai
AU - Watts, Norman R.
AU - Cheng, Naiqian
AU - Cardone, Giovanni
AU - Stahl, Stephen J.
AU - Heller, Theo
AU - Liang, T. Jake
AU - Wingfield, Paul T.
AU - Steven, Alasdair C.
PY - 2012/1
Y1 - 2012/1
N2 - The capsid (core antigen, HBcAg) is one of three major antigens present in patients infected with Hepatitis B virus. The capsids are icosahedral particles, whose most prominent features are spikes that extend 25. å out from the contiguous "floor". At the spike tip are two copies of the "immunodominant loop". Previously, the epitopes of seven murine monoclonal antibodies have been identified by cryo-EM analysis of Fab-labeled capsids. All but one are conformational and all but one map around the spike tip. The exception, which is also the tightest-binder, straddles an inter-molecular interface on the floor. Seeking to relate these observations to the immunological response of infected humans, we isolated anti-cAg antibodies from a patient, prepared Fabs, and analyzed their binding to capsids.. A priori, one possibility was that many different Fabs would give an undifferentiated continuum of Fab-related density. In fact, the density observed was highly differentiated and could be reproduced by modeling with just five Fabs, three binding to the spike and two to the floor. These results show that epitopes on the floor, far (∼30. å) from the immunodominant loop, are clinically relevant and that murine anti-cAg antibodies afford a good model for the human system.
AB - The capsid (core antigen, HBcAg) is one of three major antigens present in patients infected with Hepatitis B virus. The capsids are icosahedral particles, whose most prominent features are spikes that extend 25. å out from the contiguous "floor". At the spike tip are two copies of the "immunodominant loop". Previously, the epitopes of seven murine monoclonal antibodies have been identified by cryo-EM analysis of Fab-labeled capsids. All but one are conformational and all but one map around the spike tip. The exception, which is also the tightest-binder, straddles an inter-molecular interface on the floor. Seeking to relate these observations to the immunological response of infected humans, we isolated anti-cAg antibodies from a patient, prepared Fabs, and analyzed their binding to capsids.. A priori, one possibility was that many different Fabs would give an undifferentiated continuum of Fab-related density. In fact, the density observed was highly differentiated and could be reproduced by modeling with just five Fabs, three binding to the spike and two to the floor. These results show that epitopes on the floor, far (∼30. å) from the immunodominant loop, are clinically relevant and that murine anti-cAg antibodies afford a good model for the human system.
KW - Antibody labeling
KW - Conformational epitopes
KW - Immunodominant epitopes
KW - Molecular modeling
KW - Polyclonal antibodies
UR - http://www.scopus.com/inward/record.url?scp=84855854230&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84855854230&partnerID=8YFLogxK
U2 - 10.1016/j.jsb.2011.10.003
DO - 10.1016/j.jsb.2011.10.003
M3 - Article
C2 - 22056468
AN - SCOPUS:84855854230
SN - 1047-8477
VL - 177
SP - 145
EP - 151
JO - Journal of Structural Biology
JF - Journal of Structural Biology
IS - 1
ER -