(A) SARS-CoV-2 binds with host cell ACE2 receptor resulting in
fusion, either (B1) endocytosis or (B2) priming
cleavage by TMPRSS2; shedded ACE2 also augments viral entry by either
activated ADAM17 or TMPRSS2. (B1a) Endocytosed virus S protein
is also cleaved by cathepsin L; (C) Virus RNA genome is
liberated into cytoplasm and (D) translation into polypeptides
takes place into endoplasmic reticulum derived double membrane vesicles;
(E) Polyproteins are cleaved into NSPs; (F)
Translation of structural proteins and RNA replication; (G)
Trafficking of newly synthesized proteins and RNA from endoplasmic
reticulum to Golgi body; (H) Packaging of virion in the budding vesicle;
(I) Mature virus releases via exocytosis; (J)
SARS-CoV-2 antigens presentation to antigen presenting cells via MHCs /
HLAs; (K) Stimulated antigen presenting cells releases
cytokines to enhance proinflammatory response. [In both pathways,
furin / heparan sulphate could cleave S2’ site for successful viral
entry and replication]. (Adapted and modified from
https://www.genetex.com/Research/Overview/infectious_diseases/SARS-CoV-2?fbclid=IwAR0T8T8J75gdjt1z6Uuvh6KEdsJNDO6Ja8xuhso5Q0SDlkdkwATY077cMxo)