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Virus Research

The publication of the 2003 PNAS paper initiated a change within Gelbart’s research career because it was a blow from the past, since his past research was in chemical physics and general physical chemistry. But, he had a coordinated endeavor to learn the techniques, concepts, language, and challenges of a completely new field, biology and viruses. Gelbart was able to participate in an extremely comprehensive summer molecular biology boot camp. Colleagues, postdocs, and students were so interested in helping by providing materials and using their expertise to help. With several colleagues, he was able to comprehend that a bulk of viral capsids have icosahedral symmetry. Next, he published another paper with Mr. Mason by actually joining viral capsid proteins with water/oil nano-emulsion droplets and showing the reliance of capsid stability on curvature. Further theoretical work was covered by more postdocs on models of viral budding and capsid elasticity. On 2004, Gelbart and Mr. Knobler had begun experiments on simple RNA viruses. They worked with CCMV, a spherical plant virus, reconstructed from its constituents. Work on a simple enveloped virus, where the capsid is surrounded by a lipid bilayer membrane, as is the case with most mammalian viruses, was begun in 2005.[1]

The shape transition of icosahedral viral capsids from spherical to buckled/faceted as their radius rises through a critical value determined by the competition between stretching and bending energies of a closed 2D elastic network. The fact that there is nonzero spontaneous curvature plays a huge role in this. However, another idea is correlated with the unique method where the energy of the 12 fivefold sites depends on the background local curvature of the shell in which they are embedded. They discover that the transition from icosahedral to spherocylindrical symmetry is continuous or weakly first order near the dawning of buckling, leading to extensive shape degeneracy. The results of various experimentally observed variations in the shapes of a variety of viral capsids.[2]

These viruses can be made from purified components and they can even be made by two items: a single molecule of nucleic acid plus bountiful numbers of the same protein. By making the interactions between proteins sufficiently weak, they are able to stall the assembly process and interrogate the structure and composition of particular on-pathway intermediates. Additionally, they find that the strength of the lateral attractions between RNA-bound proteins plays a key role in addressing several outstanding questions about assembly.[3]

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[1] "Biography of William M. Gelbart." Biography of William M. Gelbart - The Journal of Physical Chemistry B (ACS Publications). Ed. Avinoam Ben-Shaul, Charles M. Knobler, and Andrea J. Liu. American Chemical Society, 7 July 2016. Web. 8 Nov. 2016.

[2] Nguyen, T. T., Robijn F. Bruinsma, and William M. Gelbart. "Elasticity Theory and Shape Transitions of Viral Shells." Physical Review E. American Physical Society, 21 Nov. 2005. Web. 16 Nov. 2016.

[3] Garmann, Rees F., Mauricio Comos-Garcia, Charles M. Knobler, and William M. Gelbart. "Physical Principles in the Self-Assembly of a Simple Spherical Virus." Physical Principles in the Self-Assembly of a Simple Spherical Virus - Accounts of Chemical Research (ACS Publications). American Chemical Society, 10 Dec. 2015. Web. 16 Nov. 2016.