Fig. 13: Schematic representation of the design of proteolysis-targeting (PROTAR) attenuated viruses.
From: Synthetic biology-inspired development of live attenuated influenza vaccines

Proteasome-targeting degrons (PTDs) are incorporated into viral proteins. In conventional cells, the PTDs are recognized by their respective E3 ubiquitin ligases, which polyubiquitinate the viral proteins, targeting them for degradation by the proteasome, leading to proteasomal viral protein degradation.