SARS-CoV-1 mRNA is translated according to the ribosomal scanning model. Virus mRNA is capped and polyadenylated, with regions of nontranslated sequences on both the 5' and 3' ends. Structural proteins are encoded after the polymerase/replicase genes by mRNAs 2 (Spike protein), 3, 4 (Envelope protein), 5 (Membrane protein), and 9. mRNA 3 and 9 are bicistronic, the proteins 3a and 9a (Nucleocapsid protein) having functions in virus assembly and structure. Translation happens in the ER with the exception of 9a which is translated by cytosolic free ribosomes (Fung and Liu, 2019).