Table 1.
Types of interferons, antiviral functions, and their cellular receptors.
| IFN type | Subtype | Chomosomal locus | Celluar source | Antiviral function | IFN receptor | Receptor distribution |
|---|---|---|---|---|---|---|
| Type I IFN | IFN-α (17 for pig, and 13 for human), IFN-β (1), IFN-ε (1), IFN-κ (1), IFN-ω (1) |
1 for pig, 9 for human, 4 for mouse |
Nearly all nucleated cells produce IFN-β. IFN-α subtypes are primarily produced by leukocytes. pDCs are the most potent type I IFN producers. IFN-κ and IFN-ε produced in a tissue-specific manner. |
Potent antiviral activities. | IFNAR1 and IFNAR2 | Nearly all nucleated cells, except intestinal epithelial cells (IECs). |
| Type II IFN | IFN-γ (1) | 5 for pig, 12 for human, 10 for mouse |
Made primarily by immune cells such as CD4 and CD8 T cells, NK and NKT cells, DCs, and macrophages. | More of an interleukin than an interferon. Modest antiviral activity. |
IFNGR1 and IFNGR2 | Broad tissue distribution. |
| Type III IFN | IFN-λ (4) | 14 for pig, 19 for human, 7 for mouse |
A variety of human primary cell types of hematopoietic lineage. Epithelial cells are the potent producers for type III IFNs among the nonhematopoietic cells. |
Largelyrestricted to epithelium. lung epithelium responds to both type I and III IFNs. IECs respond exclusively to type III IFNs. |
IFNLR1 and IL-10R2 |
IL-10R2 is widely distributed across cell types. IFNLR1 is mainly restricted to epithelial cells. |