ISDA

Entry Detail

PDB ID:

9J66

EMDB ID:

EMD-61167

Keywords:

VIRAL PROTEIN

Title:

Cryo-EM structure of the SARS-CoV-2 S 6P trimer in complex with the human neutralizing antibody Fab fragment CAV-C65 (local refinement)

Biological Source:

Source Organism:

Homo sapiens, Severe acute respiratory syndrome coronavirus 2

Host Organism:

Homo sapiens

PDB Version:

Deposition Date:

2024-08-15

Release Date:

2025-03-12

Method Details:

Experimental Method:

ELECTRON MICROSCOPY

Resolution:

3.55 Å

Aggregation State:

PARTICLE

Reconstruction Method:

SINGLE PARTICLE

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Macromolecular Entities

Protein Blast

Polymer Type:polypeptide(L)
Description:Spike protein S1
Chain IDs:C (auth: A), D
Chain Length:195
Number of Molecules:2
Biological Source:Severe acute respiratory syndrome coronavirus 2

UniProt ID:P0DTC2 Pfam ID:PF09408

Polymer Type:polypeptide(L)
Description:CAV-C65 Heavy chain
Chain IDs:A (auth: B)
Chain Length:231
Number of Molecules:1
Biological Source:Homo sapiens

Polymer Type:polypeptide(L)
Description:CAV-C65 Light chain
Chain IDs:B (auth: C)
Chain Length:214
Number of Molecules:1
Biological Source:Homo sapiens

Ligand Molecules

Primary Citation

IgA class switching enhances neutralizing potency against SARS-CoV-2 by increased antibody hinge flexibility.

Xu, M, Zhang, Z, Sun, Y, Mai, H, Liu, S, Liu, S, Lv, K, Yu, F, Wang, Y, Yue, X, Zhang, J, Cai, X, Zhao, R, Lu, H, Liu, L, Luo, H, Zhao, H, Wang, Y, Gong, P, Chen, S, Jing, X, Zhao, J, Chen, Y.Q.Show

Antiviral Res. 235 106082 106082 (2025)

PMID: 39828085 DOI: 10.1016/j.antiviral.2025.106082

Abstact

IgA antibodies are critical components of the mucosal immune barrier, providing essential first-line defense against viral infections. In this study, we investigated the impact of antibody class switching on neutralization efficacy by engineering recombinant antibodies of different isotypes (IgA1, IgG1) with identical variable regions from SARS-CoV-2 convalescent patients. A potent, broad-spectrum neutralizing monoclonal antibody CAV-C65 exhibited a ten-fold increase in neutralization potency upon switching from IgG1 to IgA1 monomer. Structural analysis revealed that this antibody binds to two adjacent receptor binding domains on the spike protein. Enhanced neutralization by IgA1 was attributed to the combined effects of increased affinity, unique hinge region properties, and potential cross-linking of viral particles. Inhaled CAV-C65 IgA1 demonstrated prophylactic efficacy against lethal SARS-CoV-2 infection in hACE2 mice. These findings highlight the pivotal role of IgA in antiviral immunity and inform the development of IgA-based therapeutics.

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Primary Citation of related structures