In Support of Simian Polyomavirus 40 VP4 as a Later Expressed Viroporin

Simian virus 40 VP4 was discovered in 2007 as a later expressed viral protein initiated from a downstream Met on the VP2/VP3 transcript. VP4's role as a viroporin involved in viral release was supported in a series of additional articles that characterized the ability of VP4 to associate with and permeabilize biological membranes. This commentary is our response to the perspective from Henriksen and Rinaldo (mSphere 5:e00019-20, 2020, https://doi.org/10.1128/mSphere.00019-20) that challenges the existence of SV40 VP4.