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Applying Distinct CDMS Strategies to Observe Nonclassical Virus Capsid Assembly
Lars Thiede1,2, Anisha Haris3, Tomislav Damjanović1,2
1CSSB Centre for Structural Systems Biology, Deutsches Elektronen-Synchrotron DESY & Leibniz Institute of Virology (LIV) & University of Luebeck, Hamburg, Germany.
Journal of Mass Spectrometry : JMS
|May 28, 2026
Summary
Charge detection mass spectrometry (CDMS) accurately measured masses of human norovirus capsids. This study highlights CDMS capabilities for analyzing complex viral structures and reveals novel capsid assemblies.
Area of Science:
- Structural biology
- Mass spectrometry
- Virology
Background:
- Conventional native mass spectrometry (MS) struggles with heterogeneous, high-mass samples like viral capsids, limiting accurate mass determination.
- Charge detection mass spectrometry (CDMS) simultaneously measures mass-to-charge ratio (m/z) and charge (z), enabling analysis of complex biomolecules.
- Human noroviruses form heterogeneous T=3 and T=4 capsids, posing challenges for precise structural characterization.
Purpose of the Study:
- To compare the performance of two commercial CDMS systems (Orbitrap-based DMT and ELIT-based Xevo) for analyzing human norovirus capsids.
- To investigate the structural heterogeneity and mass distribution of GI.1 Norwalk and GII.17 Kawasaki norovirus strains.
- To identify potential nonclassical capsid assemblies and interactions affecting viral structure.
Main Methods:
- Analysis of human norovirus capsids (GI.1 Norwalk and GII.17 Kawasaki) using Orbitrap-based Direct Mass Technology (DMT) and Xevo CDMS.
- Comparison of experimental mass data with theoretical masses for T=3 and T=4 capsid structures.
- Confirmation of structural findings using cryogenic electron microscopy (cryo-EM) and proteomics.
Main Results:
- Both CDMS systems successfully determined similar masses for both norovirus strains.
- GII.17 Kawasaki exhibited both T=3 and T=4 particles, with Xevo CDMS providing measurements closer to theoretical mass.
- GII.17 Kawasaki displayed nonclassical mass distributions and an oval capsid shape, confirmed by cryo-EM. GI.1 Norwalk showed mass exceeding theoretical T=3 by 8-10%, potentially due to expression system protein interactions.
Conclusions:
- CDMS is a powerful technique for characterizing heterogeneous viral capsids, with distinct instruments offering complementary data.
- The study identified the first nonclassical capsid assembly in a GII.17 noroviral capsid, revealing an oval shape.
- GI.1 Norwalk capsids may engage in interactions with expression system proteins, contributing to observed mass heterogeneity.
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