Question

Why is it not possible to make an icosahedral virus particle with a T (triangulation) number of 147 using a single protein subunit?

Answer 1

In these dsDNA spherical viruses, the capsid consists of 360 copies of the major capsid protein VP1. Such a number cannot be accommodated on a triangulated icosahedral lattice because T = 6 (360/60) is forbidden as it does not adhere H 2 + HK + K 2 rule.