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Recombinant Viral B18R Protein, CF

Bio-Techne includes R&D Systems | Catalog # 8185-BR

Type I IFN Inhibitor
Catalog #
Size / Price

Key Product Details



Accession #

Structure / Form

Disulfide-linked homodimer





Product Specifications


Human embryonic kidney cell, HEK293-derived viral B18R protein
MD Human IgG1
IEGR Viral B18R
Accession # P25213
N-terminus C-terminus


>90%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.

Endotoxin Level

<0.10 EU per 1 μg of the protein by the LAL method.

N-terminal Sequence Analysis


Predicted Molecular Mass

65 kDa (monomer)


80-95 kDa, reducing conditions


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.

Scientific Data Images for Recombinant Viral B18R Protein, CF

B18R Inhibits Type-I IFN-mediated anti-viral activity.

B18R Inhibits Type-I IFN-mediated anti-viral activity.

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.

Formulation, Preparation and Storage

Formulation Lyophilized from a 0.2 μm filtered solution in PBS.
Reconstitute at 500 μg/mL in PBS.

Reconstitution Buffer Available:
Size / Price
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.

Background: B18R

B18R (Soluble IFN 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 IFN receptor B18R, however, contains three immunoglobulin-like domains and shows homology to human, mouse, and bovine type I IFN 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 IFNs (IFN alpha, beta, omega). It binds to type I IFNs 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 IFNs, 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). The B18R viral protein also acts to protect cells during mRNA transfection to produce induced pluripotent stem cells (iPSCs) from somatic cells (10). The addition of B18R results in increased cell viability of iPSCs in the presence of modified synthetic mRNAs such as OCT4, SOX2, KLF4, MYC, NANOG, and LIN28A. Using mRNAs in combination with B18R allows for integration-free reprogramming of somatic cells to iPSCs without the use of viral vectors or genomic modification.


  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)

Gene Symbol



Additional B18R Products

Product Documents for Recombinant Viral B18R Protein, CF

Certificate of Analysis

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Note: Certificate of Analysis not available for kit components.

Product Specific Notices for Recombinant Viral B18R Protein, CF

For research use only