Table 1.
Genome and structure, target cell type, and sensitivity to protease/antiprotease balance of respiratory viruses
| Respiratory Virus | Genome; Structure | Target Cell | Require Proteolytic Cleavage by Secreted Respiratory Proteases? | Sensitive to Secreted Respiratory Antiproteases? |
|---|---|---|---|---|
| Adenovirus | dsDNA; Nonenveloped | Epithelial cells using clathrin-dependent entry mechanisms (119) | No | No |
| Rhinoviruses | +ssRNA; Nonenveloped | Epithelial cells of the upper airway expressing ICAM-1 (69) | No | No |
| Enteroviruses | +ssRNA; Nonenveloped | Epithelial cells expressing ICAM-1 or DAF (129) | No | No |
| Coronaviruses | +ssRNA; Enveloped | Epithelial cells expressing ACE2 or DPP4 (107, 139) | Yes- cleave S protein (17, 19, 20, 64, 77, 157, 194) | Yes (96, 142) |
| Measles viruses | -ssRNA; Enveloped | Epithelial cells expressing nectin 4 (132, 133) | No | No |
| Metapneumoviruses | -ssRNA; Enveloped | Upper and lower airway epithelial cells expressing αVβ1 integrin (39) | Yes- cleave F protein (158) | No |
| Respiratory syncytial viruses | -ssRNA; Enveloped | Epithelial cells expressing sulfated glycosamino-glycans (70) | No | No |
| Parainfluenza viruses | -ssRNA; Enveloped | Epithelial cells expressing 2,3 or 2,6 linked sialic acid residues (55) | Yes- cleave F protein (3, 94) | Yes (52, 93, 94) |
| Influenza viruses | -ssRNA; Enveloped | Epithelial cells expressing 2,3 or 2,6 linked sialic acid residues (36) | Yes- cleave HA protein (10, 11, 16, 19, 22, 23, 56, 75, 148, 178, 194) | Yes (14, 91, 93, 95) |