I think that you have identified it correctly. Virtue standing left, holding spear in left hand, right hand resting on shield.
There are several minor variations of the VIRTVS reverse issued from a few mints, all with different RIC numbers.
Antoninianii were issued in huge numbers during the reign of Gallienus to pay the troops, due to a big uprise in unrest both on the frontiers of the Empire, and within.
Because of this, it is possible to occasionally find silvered antoninianii of this Emperor in almost 'as struck' condition.