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In Vitro Disassembly of Influenza A Virus Capsids by Gradient Centrifugation
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Molecular jenga: the percolation phase transition (collapse) in virus capsids
Nicholas E Brunk1,2, Lye Siang Lee1, James A Glazier2,3
1Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, United States of America.
Physical Biology
|May 2, 2018
Summary
Graph theory and percolation models reveal critical insights into virus capsid stability. Removing over 25% of subunits triggers abrupt fragmentation, near the experimentally observed percolation threshold for hepatitis B virus capsids.
Area of Science:
- Virology
- Biophysics
- Computational Biology
Background:
- Virus capsids are protein shells protecting viral genetic material.
- Icosahedral capsids, common in viruses, self-assemble from numerous subunits.
- Capsid disassembly is vital for viral lifecycles but remains poorly understood.
Purpose of the Study:
- To investigate the impact of subunit removal on icosahedral capsid stability and fragmentation using graph and percolation theory.
- To quantitatively predict capsid dissociation behavior based on structural properties.
Main Methods:
- Constructed a graph model of the hepatitis B virus (HBV) capsid using rhombic subunits with icosahedral symmetry.
- Applied graph and percolation theory to simulate subunit removal and assess capsid fragmentation.
- Compared theoretical predictions with experimental data on HBV capsid dissociation.
Main Results:
- The capsid graph exhibited a gradual quadratic decay in stability as subunits were removed.
- Abrupt fragmentation of the capsid structure occurred when approximately 25% of subunits were removed, aligning with the percolation threshold.
- The findings are consistent with experimental observations of HBV capsid dissociation and may explain the prevalence of 90-mer intermediates during assembly.
Conclusions:
- Percolation theory provides a quantitative framework for understanding virus capsid stability and dissociation.
- The identified percolation threshold offers insights into the mechanisms governing capsid assembly and disassembly.
- This approach can generalize to other icosahedral viruses, linking viral biology to particle biophysics.
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