Fig. 2

Depicts the SARS-CoV-2 life cycle. When the SARS-CoV-2 spike protein binds to the target cell receptor ACE2, the S protein is cleaved by host cell proteases, such as TMPRSS2, triggering fusion of the virus with the plasma membrane. In addition, SARS-CoV-2 can enter cells through endocytosis. The N protein is the dissociated from the positive strand (+) RNA genome of SARS-CoV-2 and translated into polyproteins pp1a and pp1ab. These polyproteins are translated and processed into nonstructural proteins nsp1-16, which build viral replication and transcription complexes (RTCs) and reshape the cell membrane to form replicating organelles (DMVs). These organelles form a continuum with the endoplasmic reticulum, and viral RNA replication mainly occurs in DMVs. The newborn virus RNA exits DMVs through transmembrane pores to reach the location for translation or virion assembly. The translated structural proteins are transported to the endoplasmic reticulum (ER) membrane and transit through the ER-to-Golgi intermediate compartment (ERGIC). The positive strand RNA of the genome wrapped by the N protein undergoes assembly with structural proteins S, M, and E, and new virions are formed by budding into the lumen at ERGIC. Finally, the progeny virions are released from the host cell