4LU5: Structure Of Murine Igg2a A20g2-fab In Complex With Vaccinia Antigen A33r At The Resolution Of 2.9 Angstroms

Citation:
Abstract
Vaccinia virus A33 is an extracellular enveloped virus (EEV)-specific type II membrane glycoprotein that is essential for efficient EEV formation and long-range viral spread within the host. A33 is a target for neutralizing antibody responses against EEV. In this study, we produced seven murine anti-A33 monoclonal antibodies (MAbs) by immunizing mice with live VACV, followed by boosting with the soluble A33 homodimeric ectodomain. Five A33 specific MAbs were capable of neutralizing EEV in the presence of complement. All MAbs bind to conformational epitopes on A33 but not to linear peptides. To identify the epitopes, we have adetermined the crystal structures of three representative neutralizing MAbs in complex with A33. We have further determined the binding kinetics for each of the three antibodies to wild-type A33, as well as to engineered A33 that contained single alanine substitutions within the epitopes of the three crystallized antibodies. While the Fab of both MAbs A2C7 and A20G2 binds to a single A33 subunit, the Fab from MAb A27D7 binds to both A33 subunits simultaneously. A27D7 binding is resistant to single alanine substitutions within the A33 epitope. A27D7 also demonstrated high-affinity binding with recombinant A33 protein that mimics other orthopoxvirus strains in the A27D7 epitope, such as ectromelia, monkeypox, and cowpox virus, suggesting that A27D7 is a potent cross-neutralizer. Finally, we confirmed that A27D7 protects mice against a lethal challenge with ectromelia virus.
PDB ID: 4LU5Download
MMDB ID: 121882
PDB Deposition Date: 2013/7/24
Updated in MMDB: 2015/09
Experimental Method:
x-ray diffraction
Resolution: 2.9  Å
Source Organism:
Vaccinia virus
Similar Structures:
Biological Unit for 4LU5: hexameric; determined by author
Molecular Components in 4LU5
Label Count Molecule
Proteins (6 molecules)
2
A33r
Molecule annotation
2
Murine Igg2a A20g2 Heavy Chain FAB Domain
Molecule annotation
2
Murine Igg2a A20g2 Light Chain FAB Domain
Molecule annotation
* Click molecule labels to explore molecular sequence information.

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