scholarly journals A Cryo-Electron Microscopy Study Identifies the Complete H16.V5 Epitope and Reveals Global Conformational Changes Initiated by Binding of the Neutralizing Antibody Fragment

2014 ◽  
Vol 89 (2) ◽  
pp. 1428-1438 ◽  
Author(s):  
Hyunwook Lee ◽  
Sarah A. Brendle ◽  
Stephanie M. Bywaters ◽  
Jian Guan ◽  
Robert E. Ashley ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Conformational Changes ◽  
Antibody Fragment ◽  
Neutralizing Antibody ◽  
Conformational Epitope ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Etiologic Agent ◽  
Cryo Electron Microscopy ◽  
Antigenic Properties

ABSTRACTHuman papillomavirus 16 (HPV16) is a worldwide health threat and an etiologic agent of cervical cancer. To understand the antigenic properties of HPV16, we pursued a structural study to elucidate HPV capsids and antibody interactions. The cryo-electron microscopy (cryo-EM) structures of a mature HPV16 particle and an altered capsid particle were solved individually and as complexes with fragment of antibody (Fab) from the neutralizing antibody H16.V5. Fitted crystal structures provided a pseudoatomic model of the virus-Fab complex, which identified a precise footprint of H16.V5, including previously unrecognized residues. The altered-capsid–Fab complex map showed that binding of the Fab induced significant conformational changes that were not seen in the altered-capsid structure alone. These changes included more ordered surface loops, consolidated so-called “invading-arm” structures, and tighter intercapsomeric connections at the capsid floor. The H16.V5 Fab preferentially bound hexavalent capsomers likely with a stabilizing effect that directly correlated with the number of bound Fabs. Additional cryo-EM reconstructions of the virus-Fab complex for different incubation times and structural analysis provide a model for a hyperstabilization of the capsomer by H16.V5 Fab and showed that the Fab distinguishes subtle differences between antigenic sites.IMPORTANCEOur analysis of the cryo-EM reconstructions of the HPV16 capsids and virus-Fab complexes has identified the entire HPV.V5 conformational epitope and demonstrated a detailed neutralization mechanism of this clinically important monoclonal antibody against HPV16. The Fab bound and ordered the apical loops of HPV16. This conformational change was transmitted to the lower region of the capsomer, resulting in enhanced intercapsomeric interactions evidenced by the more ordered capsid floor and “invading-arm” structures. This study advances the understanding of the neutralization mechanism used by H16.V5.

scholarly journals Cryo-electron microscopy study of bacteriophage T4 displaying anthrax toxin proteins

Virology ◽  
2007 ◽  
Vol 367 (2) ◽  
pp. 422-427 ◽  
Author(s):  
Andrei Fokine ◽  
Valorie D. Bowman ◽  
Anthony J. Battisti ◽  
Qin Li ◽  
Paul R. Chipman ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Bacteriophage T4 ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Anthrax Toxin ◽  
Cryo Electron Microscopy

scholarly journals Structural basis of actin filament capping at the barbed-end: a cryo-electron microscopy study

2006 ◽  
Vol 25 (23) ◽  
pp. 5626-5633 ◽  
Author(s):  
Akihiro Narita ◽  
Shuichi Takeda ◽  
Atsuko Yamashita ◽  
Yuichiro Maéda
Keyword(s):  
Electron Microscopy ◽  
Actin Filament ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Structural Basis ◽  
Cryo Electron Microscopy

scholarly journals Near-Atomic Resolution Structure of a Highly Neutralizing Fab Bound to Canine Parvovirus

2016 ◽  
Vol 90 (21) ◽  
pp. 9733-9742 ◽  
Author(s):  
Lindsey J. Organtini ◽  
Hyunwook Lee ◽  
Sho Iketani ◽  
Kai Huang ◽  
Robert E. Ashley ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Receptor Binding ◽  
Conformational Changes ◽  
De Novo ◽  
Mutational Analysis ◽  
Antibody Fragment ◽  
Canine Parvovirus ◽  
Single Chain ◽  
Cryo Electron Microscopy ◽  
Resolution Structure

ABSTRACT Canine parvovirus (CPV) is a highly contagious pathogen that causes severe disease in dogs and wildlife. Previously, a panel of neutralizing monoclonal antibodies (MAb) raised against CPV was characterized. An antibody fragment (Fab) of MAb E was found to neutralize the virus at low molar ratios. Using recent advances in cryo-electron microscopy (cryo-EM), we determined the structure of CPV in complex with Fab E to 4.1 Å resolution, which allowed de novo building of the Fab structure. The footprint identified was significantly different from the footprint obtained previously from models fitted into lower-resolution maps. Using single-chain variable fragments, we tested antibody residues that control capsid binding. The near-atomic structure also revealed that Fab binding had caused capsid destabilization in regions containing key residues conferring receptor binding and tropism, which suggests a mechanism for efficient virus neutralization by antibody. Furthermore, a general technical approach to solving the structures of small molecules is demonstrated, as binding the Fab to the capsid allowed us to determine the 50-kDa Fab structure by cryo-EM. IMPORTANCE Using cryo-electron microscopy and new direct electron detector technology, we have solved the 4 Å resolution structure of a Fab molecule bound to a picornavirus capsid. The Fab induced conformational changes in regions of the virus capsid that control receptor binding. The antibody footprint is markedly different from the previous one identified by using a 12 Å structure. This work emphasizes the need for a high-resolution structure to guide mutational analysis and cautions against relying on older low-resolution structures even though they were interpreted with the best methodology available at the time.

scholarly journals Antibody-induced uncoating of human rhinovirus B14

2017 ◽  
Vol 114 (30) ◽  
pp. 8017-8022 ◽  
Author(s):  
Yangchao Dong ◽  
Yue Liu ◽  
Wen Jiang ◽  
Thomas J. Smith ◽  
Zhikai Xu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Virus Infection ◽  
Conformational Changes ◽  
Neutralizing Antibody ◽  
Antigen Binding ◽  
Fab Fragment ◽  
Cryo Electron Microscopy ◽  
Virus Complex ◽  
Positive Strand Rna ◽  
Icosahedral Capsid

Rhinoviruses (RVs) are the major causes of common colds in humans. They have a nonenveloped, icosahedral capsid surrounding a positive-strand RNA genome. Here we report that the antigen-binding (Fab) fragment of a neutralizing antibody (C5) can trigger genome release from RV-B14 to form emptied particles and neutralize virus infection. Using cryo-electron microscopy, structures of the C5 Fab in complex with the full and emptied particles have been determined at 2.3 Å and 3.0 Å resolution, respectively. Each of the 60 Fab molecules binds primarily to a region on viral protein 3 (VP3). Binding of the C5 Fabs to RV-B14 results in significant conformational changes around holes in the capsid through which the viral RNA might exit. These results are so far the highest resolution view of an antibody–virus complex and elucidate a mechanism whereby antibodies neutralize RVs and related viruses by inducing virus uncoating.

Sign in / Sign up

Export Citation Format

Share Document