Certainly one of the most intriguing facts about viruses is that the large majority of them display full icosahedral symmetry, arguably the highest and also the most esthetically-pleasing symmetry shown in Nature. The elements of icosahedral symmetry involve 6 five-fold rotation axes, 10 three-fold, and 15 two-fold.

We know from our studies with lambda phage that viral capsids can support internal pressures of 50 - 60 atm. The interactions between the proteins that make up the capsid are held together by hydrophobic and electrostatic forces and hydrogen bonds. How can structures that are joined by relatively weak bonds be so strong? Just how strong are viral capsids?