REGULATION OF CORONAVIRUS PROTEIN STOICHIOMETRIC RATIOS

Viruses have developed diverse strategies to ensure the optimal expression ratio of each viral protein.  In the case of coronaviruses, replicase proteins are expressed from a full-length gRNA by translation of two polyproteins that are proteolytically  cleaved. In contrast, structural and  accessory proteins are expressed from a nested set of sgmRNAs. Therefore, the abundance of each sgmRNA must be tightly regulated during the discontinuous transcription process to ensure appropriate viral protein ratios.