I am looking to establish a stable cell line expressing flavivirus structural proteins as a trans-packaging system to observe single-round infectious cycles with a replicon.

Looking at the literature, I mostly see non cytopathic VEEV or KUNV based systems to produce the structural CprME protein for the flavivirus of interest. Can someone walk me through the thinking behind this?

Why not having a simple plasmid with let say a CMV promoter expressing CprME stably in the cell, instead of a viral-like system more likely to trigger an immune response?

Especially that the viral protease is not essential here and, to my understanding, its cleavage site on C can easily be replaced by a FMDV 2A auto-cleavage site...