Fig. 2.

The process of coronavirus (CoV) VLP assembly in eukaryotic cells. The structural genes of CoV are introduced into mammalian cell systems or baculovirus-insect cell systems. N proteins are translated on free polysomes. S, E and M proteins are translated on membrane-bound polysomes, inserted into the endoplasmic reticulum (ER), and transported into the ER–Golgi intermediate compartment (ERGIC). M protein directs the assembly process by interacting with every constituent of the VLP. The number in the dashed box indicates the order of interaction of each protein with M protein in the ERGIC. VLPs are transported to the cell surface in vesicles and exocytotically released.