  Recent high resolution structures for viral capsids with 12, 32 and 72
subunits ($T1$, $T3$ and $T7$ viruses) have confirmed theoretical predictions
of an icosadeltahedral structure with 12 subunits having five nearest neighbors
(pentamers) and $(10T+2)-12$ subunits having six nearest neighbor subunits
(hexamers). Here we note that theoretical considerations of energy strain for
$T4$, $T9$ $T16$ and $T25$ viruses by aligned pentamers and energy strain along
with the sheer number of possible arrangement of pentamers as the number of
subunits grows, and simulations for such numbers of subunits make an
icosadeltahedral configuration either miraculously unlikely or indicate that
there must be a principle of capsid assembly of unprecedented fidelity in
Nature. We predict, for example, that high resolution data will show $T4$
capsids to have $D_{5h}$ not icosahedral symmetry.
