Recombinant B18R protein (Vaccinia Virus-Encoded Neutralizing Type I Interferon Receptor)

The B18R protein is a vaccinia virus-encoded receptor with specificity for mouse, human rabbit, pig, rat, and cow type I interferons and which has potent neutralizing activity. The B18R protein is a type I interferon receptor encoded by the B18R gene of the Western Reserve vaccinia virus strain. The 60-65 kD a glycoprotein is related to the interleukin-1 receptors and is a member of the immunoglobulin superfamily, unlike other type I IFN-receptors, which belong to the class II cytokine receptor family. The B18R protein has a high affinity (KD, 174 pM) for human IFN alpha and, unlike other type I IFN receptors, has broad species specificity, binding to type I interferons of human, mouse, rat, rabbit, pig, and cow. Among viral host response modifiers, the B18R protein is unique in that it exists as a soluble extracellular, as well as a cell surface protein, enabling blockage of both autocrine and paracrine IFN functions. The B18R protein has been shown to inhibit the antiviral potency of IFN-alpha1, IFN-alpha2 , IFN-alpha-8/1/8, and IFN-omega on human cells. The soluble B18R protein is highly potent for neutralizing type I interferons, which include IFN-alpha, beta, delta, kappa.

Figure 1: B18R Protein Neutralization of Exogenous Human IFN-alpha2a Induced Downregulation of IL-12 p40 Expression. Human PBMCs were treated with irradiated CD40L-transfected L cells in the presence or absence of IFN-alpha2a (1 ng/ml; cell pre-treatment) and B18R protein (0.1 ug/ml, 0.01 ug/ml, 0.001 ug/ml). IL-12 p40 protein levels were determined by ELISA. CD40L-induced IL-12 p40 is downregulated by pretreatment of PBMCs with IFN-alpha2a (Column 2 vs 1). Inclusion of B18R protein abrogates the effect of IFN-alpha2a (Columns 3-5). Similar effects of B18R were seen with exogenous human IFN-beta and CpG induced endogenous type I interferon (data not shown). (Nagai, T., et al. 2003. J. Immunol. 171: 5233-43.)

Product Information

Contents: Recombinant B18R protein (Vaccinia Virus-Encoded Neutralizing Type I Interferon Receptor)
Catalog Number: 14-8185
Concentration: 100 ug/ml
Formulation: Sterile liquid; phosphate buffered saline, pH 7.2, 150 mM NaCl, 1% BSA, 0.22 uM filtered.
Storage Conditions: For greatest stability, keep concentration of primary stock at or above 10 ug/ml. For long term storage, aliquot and store at or below -20°C. Avoid repeated freeze/thaw cycles.
Handling Conditions: For best recovery, always quick-spin vial prior to opening. For dilution of current stock (100 ug/ml), always include carrier protein (1% BSA or 10% FBS) in the buffered saline diluent.
Source: Insect cells infected with baculovirus: amino acids 22-353 of Vaccinia Virus B18R (accession # D01019).
Molecular Mass: The intact protein has a predicted molecular mass of 38,389. The DTT-reduced protein migrates as a 48 kDa polypeptide on SDS-PAGE due to glycosylation. The non-reduced protein migrates as a 46 kDa polypeptide on SDS-PAGE due to internal cystines.
Purity: Greater than 98%, as determined by SDS-PAGE.
Endotoxin Level: Less than 0.1 ng / ug B18R protein, as determined by the LAL assay.
Bioactivity: Measured by neutralization of exogenous or CpG-induced endogenous IFN-alpha or beta effects in an assay of IL-12 p40 production from CD40L-activated monocytes.

Prices for This Product*
Cat. No.	Size	Price	Qty	Action
14-8185-61	2 ug	$80
14-8185-62	5 ug	$250

*International customers: Please contact your distributor for region specific pricing.

Available Formats of This Product
Cat. No.	Format	Excite (nm)	Emit (nm)	Reported Applications
14-8185	Recombinant B18R protein (Vaccinia Virus-Encoded Neutralizing Type I Interferon Receptor; Type I IFN inhibitor)	N/A	N/A	BA
34-8185	Carrier-Free Recombinant B18R protein (Vaccinia Virus-Encoded Neutralizing Type I Interferon Receptor; Type I IFN inhibitor)	N/A	N/A	BA

Questions? Please consult our answers to frequently asked questions at http://www.ebioscience.com/faq.

Usage

For research use only, not for diagnostic or therapeutic use. Recombinant B18R is fully biologically active.

Applications Tested

This recombinant B18R protein (type I IFN receptor) has been tested in bioassay for neutralization of mouse and human interferons (alpha and beta).

References

Symons, J., et al. 1995. Vaccinia virus encodes a soluble type I interferon receptor of novel structure and broad species specificity. Cell. 81: 551-560.
Colamonici, O., et al. 1995. Vaccinia virus B18R gene encodes a type I interferon-binding protein that blocks interferon alpha transmembrane signaling. 270: 15974 – 15978.
Symons, J.A., et al. 1995. Vaccinia virus encodes a soluble type I interferon receptor of novel structure and broad species specificity. Cell 81: 551-560.
Vancova, I., et al. 1998. Vaccinia virus protein B18R inhibits the activity and cellular binding of the novel type interferon-delta. J. General Virol. 79: 1647-169.
Nagai, T., et al. 2003. Timing of IFN-beta exposure during human dendritic cell maturation and naive Th cell stimulation has contrasting effects on Th1 subset generation: a role for IFN-beta-mediated regulation of IL-12 family cytokines and IL-18 in naive Th cell differentiation. J. Immunol. 171: 5233-43. [Bioassay]