The simian virus 40 minor structural protein Vp3, but not Vp2, is essential for infectious virion formation.

The SV40 capsid is composed of pentameric capsomeres of the major structural protein Vp1. The two minor structural proteins, Vp2 and Vp3, interact with the capsid. Here, the roles of Vp2 and Vp3 were explored during the course of SV40 infection.