Figure 1: The life cycle of SARS-CoV in host cells.
From: The spike protein of SARS-CoV — a target for vaccine and therapeutic development
Severe acute respiratory syndrome-coronavirus (SARS-CoV) enters target cells through an endosomal pathway113,121,125,126,127. S protein first binds to the cellular receptor angiotensin-converting enzyme 2 (ACE2)129, and the ACE2–virus complex is then translocated to endosomes, where S protein is cleaved by the endosomal acid proteases (cathepsin L)105 to activate its fusion activity. The viral genome is released and translated into viral replicase polyproteins pp1a and 1ab, which are then cleaved into small products by viral proteinases. Subgenomic negative-strand templates are synthesized from discontinuous transcription on the plus-strand genome and serve as templates for mRNA synthesis. The full-length negative-strand template is made as a template for genomic RNA. Viral nucleocapsids are assembled from genomic RNA and N protein in the cytoplasm, followed by budding into the lumen of the ERGIC (endoplasmic reticulum (ER)–Golgi intermediate compartment)128. Virions are then released from the cell through exocytosis.
