Table 3.
Viral fusion proteins and factors that regulate their activation.
| Virus | Protein containing fusion peptide | Priming proteolytic cleavage (site) | Triggering | References |
|---|---|---|---|---|
| SARS-CoV-2 | S protein (S2 subunit) | Cleavage of S1 and S2 subunits that remain non-covalently bound (surface or endosome) | Proteolytic cleavage at the S2' site, immediately upstream of the fusion peptide | (35) |
| Nipah and Hendra henipavirus | F protein | Cleavage of F0 by cathepsin into F1 and F2 (endosome) | G protein receptor binding that mediates dissociation of the F protein | (157, 158, 163, 207) |
| New world hantavirus | Gc protein | Incompletely understood | Low pH, membrane cholesterol composition | (172) |
| Influenza A, H5N1, H7N1 (HPAIV) | HA, subunit H1 | HA0 cleaved to HA1 (receptor binding) and HA2 (fusion), subunits remain non-covalently bound. (cell surface, endosome, Golgi) | Low pH | |
| Infectious salmon anaemia virus (HPR-deleted) | F protein | Cleavage of F0 by unknown protease into F1 and F2 (location not known) | Low pH, not fully characterised | (164, 208) |