Calculation of Average Diameter: The average diameter of a capsid was estimated as follows:

Minimum and maximum radii of the capsid were estimated

The number of atoms that fall within 1 Angstrom radial shells between the minimum and maximum radii were counted.

The average diameter was calculated to be twice the largest possible radius at which the number of atoms in the corresponding shell is at least 25% of the maximum number of atoms found in any shell ( Shepherd and Reddy, 2005 ).

Chimera Surface Renderings: These renderings were created by overlaying a 3D grid of varying sizes on the atomic model. The low resolution surface utilized a grid spaced at 8 Angstroms, medium resolution used 5 Angstroms, and high resolution used 3 Angstroms. Atoms were counted in each bin of the grid, and a contour surface calculated based on these values.

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