Fig. 2

The replication cycle of SARS-CoV-2 and the targets of various therapeutic drugs. SARS-CoV-2 recognizes the ACE2 receptor on the host cell membrane via the RBD of spike protein, and enters host cell. Once uncoating, the viral genomic RNA will be used to synthesize the genomic RNA (- sense). Next, the genomic RNA is used as a template to form genomic and subgenomic mRNA (+ sense). The viral RNA and nucleocapsid protein are synthesized in the cytoplasm, while the viral spike, envelop, membrane proteins are transcribed and translated in the ER. After that, the SARS-CoV-2 are assembled to form mature virion and encapsulated in the Golgi vesicle. Viruses are released outside the host cell membrane via vesicle-mediated exocytosis, and further activate host immune system. RBD receptor-binding domain, ACE2 angiotensin-converting enzyme 2, Fc immunoglobulin fragment, scFv single-chain variable region fragments against spike protein of SARS-CoV2, ER endoplasmic reticulum