Recombinant Viral B18R Protein, CF

Type I IFN Inhibitor
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Datasheet / CoA / SDS
Product Details
Supplemental Products
  • Purity
    >90%, by SDS-PAGE under reducing conditions and visualized by silver stain.
  • Endotoxin Level
    <0.10 EU per 1 μg of the protein by the LAL method.
  • Activity
    Measured by its ability to inhibit Type-I IFN-mediated anti-viral activity. Symons, J.A. et al. (1995) Cell 81:551. The ED50 for this effect, as measured by inhibition of Recombinant Human IFN‑ alpha 2 (Catalog # 11105-1) , is 0.3-1.8 ng/mL.
  • Source
    Human embryonic kidney cell, HEK293-derived viral B18R protein
    MD Human IgG1
    IEGR Viral B18R
    Accession # P25213
    N-terminus C-terminus
  • Accession #
  • N-terminal Sequence
  • Structure / Form
    Disulfide-linked homodimer
  • Predicted Molecular Mass
    65 kDa (monomer)
    80-95 kDa, reducing conditions
Product Datasheets

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Formulation Lyophilized from a 0.2 μm filtered solution in PBS.
Reconstitution Reconstitute at 500 μg/mL in PBS.
Shipping The product is shipped at ambient temperature. Upon receipt, store it immediately at the temperature recommended below.
Stability & Storage: Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
  • 12 months from date of receipt, -20 to -70 °C as supplied.
  • 1 month, 2 to 8 °C under sterile conditions after reconstitution.
  • 3 months, -20 to -70 °C under sterile conditions after reconstitution.
Data Image
The viral type I IFN receptor, B18R, inhibits the anti-viral activity of Recombinant Human IFN-alpha 2. The ED50 for this effect is 0.3-1.8 ng/mL.
Background: B18R
B18R (Soluble interferon alpha/beta receptor B18) is a 60-65 kDa protein encoded by the Vaccinia virus genome and by the genomes of other orthopoxviruses. Its function represents one of several mechanisms used by these viruses to evade the host immune response (1, 2). It is known as B18R in the Western Reserve (WR) strain of Vaccinia but as B19R in the Copenhagen strain (3). There is a structurally-unrelated, larger Vaccinia protein that is also known as B18R (or B16R) that contains multiple ankyrin-like repeats (4). The soluble interferon receptor B18R, however, contains three immunoglobulin-like domains and shows homology to human, mouse, and bovine type I interferon receptors (5). The Wyeth strain of Vaccinia virus encodes a truncated protein that lacks the C-terminal Ig-like domain, and B18R is functionally absent in the Lister strain (6, 7). B18R functions as a decoy receptor for type I interferons (IFN alpha, beta, omega). It binds to type I interferons from multiple species and prevents IFN signaling through its receptors (6-8). B18R binds to the surface of virus infected and uninfected cells where it retains its capacity to bind and neutralize IFN (6, 8). It shields those cells from the antiviral effects of type I interferons, thereby enabling virus replication and pathogenicity (6-8). B18R also limits the effectiveness of IFN alpha produced following TLR activation (9), and it limits adaptive T cell responses (3). B18R is a common factor used for increasing the efficiency of RNA reprogramming in induced pluripotent stem cells (IPS cells) (10).

  • References:
    1. Smith, G.L. et al. (2013) J. Gen. Virol. 94:2367.
    2. Perdiguero, B. and M. Esteban (2009) J. Interferon Cytokine Res. 29:581.
    3. Gomez, C.E. et al. (2012) J. Virol. 86:5026.
    4. Goebel, S.J. et al. (1990) Virology 179:247.
    5. Smith, G.L. and Y.S. Chan (1991) J. Gen. Virol. 72:511.
    6. Alcami, A. et al. (2000) J. Virol. 74:11230.
    7. Symons, J.A. et al. (1995) Cell 81:551.
    8. Colamonici, O.R. et al. (1995) J. Biol. Chem. 270:15974.
    9. Waibler, Z. et al. (2009) J. Virol. 83:1563.
    10. Warren, L. et al. (2010) Cell Stem Cell. 7:618.
  • Long Name:
    Soluble Interferon alpha/beta Receptor B18
  • Entrez Gene IDs:
    3707577 (Viral)
  • Alternate Names:
    B18R; B19R
Related Research Areas


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