# T=31/pseudo T=31 icosahedral capsid

**Turriviridae** capsid symmetry is a pseudo T=31 structure, because hexamers are formed by 3 subunits instead of 6.

Icosahedric triangulation number is calculated following Caspar and Klug system

**Physical principles in the construction of regular viruses**

D. L. Caspar, A. Klug

Cold Spring Harb. Symp. Quant. Biol. 1962; 27: 1?24