Recombinant Viral B18R Protein, CF

Type I IFN Inhibitor
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B18R Inhibits Type-I IFN-mediated anti-viral activity.
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Product Details
Citations (3)
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Recombinant Viral B18R Protein, CF Summary

Product Specifications

>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.
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.
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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Carrier Free

What does CF mean?

CF stands for Carrier Free (CF). We typically add Bovine Serum Albumin (BSA) as a carrier protein to our recombinant proteins. Adding a carrier protein enhances protein stability, increases shelf-life, and allows the recombinant protein to be stored at a more dilute concentration. The carrier free version does not contain BSA.

What formulation is right for me?

In general, we advise purchasing the recombinant protein with BSA for use in cell or tissue culture, or as an ELISA standard. In contrast, the carrier free protein is recommended for applications, in which the presence of BSA could interfere.


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.

Scientific Data

Bioactivity B18R Inhibits Type-I IFN-mediated anti-viral activity. View Larger

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.

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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)
Alternate Names

Citations for Recombinant Viral B18R Protein, CF

R&D Systems personnel manually curate a database that contains references using R&D Systems products. The data collected includes not only links to publications in PubMed, but also provides information about sample types, species, and experimental conditions.

3 Citations: Showing 1 - 3
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  1. Interferon lambda 4 impairs hepatitis C viral antigen presentation and attenuates T cell responses
    Authors: Q Chen, M Coto-Llere, A Suslov, RD Teixeira, I Fofana, S Nuciforo, M Hofmann, R Thimme, N Hensel, V Lohmann, CKY Ng, G Rosenberge, S Wieland, MH Heim
    Nature Communications, 2021-08-12;12(1):4882.
    Species: Human
    Sample Types: Whole Cells
    Applications: Bioassay
  2. MicroRNA Profiles in Monocyte-Derived Macrophages Generated by Interleukin-27 and Human Serum: Identification of a Novel HIV-Inhibiting and Autophagy-Inducing MicroRNA
    Authors: T Imamichi, S Goswami, X Hu, S Laverdure, J Yang, J Qiu, Q Chen, BT Sherman, W Chang
    International Journal of Molecular Sciences, 2021-01-28;22(3):.
    Species: Human
    Sample Types: Whole Cells
    Applications: Neutralization
  3. Modulation of Extracellular ISG15 Signaling by Pathogens and Viral Effector Proteins
    Authors: CD Swaim, LA Canadeo, KJ Monte, S Khanna, DJ Lenschow, JM Huibregtse
    Cell Rep, 2020-06-16;31(11):107772.
    Species: Human, Mouse
    Sample Types: Whole Cells
    Applications: Bioassay


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