Recombinant B18R protein (Carrier-free)

Inhibition of interferon signaling by B18R

Type I interferon inhibitor - B18R | Carrier-free

InvivoGen offers recombinant B18R, a potent inhibitor of type I interferon (IFN) signaling. Due to its neutralizing feature, it is highly used to study host innate pattern recognition receptor (PRR) and subsequent anti-viral T cell responses upon viral infection [1-2]. B18R is also known to increase cell viability and mRNA transfection efficacy, especially during pluripotent stem cell (iPSC) reprogramming. It is able to maintain RNA-replicons and increase the viability of cells upon transfection with synthetic mRNA [3].

InvivoGen's recombinant B18R protein is produced in Chinese hamster ovary (CHO) cells, which ensures protein glycosylation and bona fide 3D structure. Of note, glycosylation stabilizes proteins against physicochemical instabilities.

It successfully blocks type I IFN-mediated signaling, as verified in HEK-Blue™ IFN-α/β cells stimulated with recombinant human IFN-α. Also, B18R increases RNA-transfection efficacy, as verified by transfecting THP1-Dual™ cells with GFP mRNA ± B18R (see figures). 

Description

B18R, also called the soluble IFN-α/β receptor B18, is naturally encoded by the western reverse (WR) strain of the vaccinia virus. It acts as a decoy receptor with specificity for mouse, human, rabbit, pig, rat, and cow type I interferons (IFNs) which represent the first line of host defenses against viral infection [4.5]. Thus, B18R effectively prevents the establishment of the antiviral state and enables virus replication and pathogenicity in virus-infected cells [6-7]. 

Key features:

• Potent inhibitor of type I interferons (e.g. IFN-α, IFN-β, IFN-κ,...) 
• Recombinant protein produced in CHO cells 
• Hexahistidine (His6) tag
• Provided carrier-free
• InvitroFit™ grade: each lot is highly pure (≥95%) and functionally tested

References:

1. Manel N, et al., 2010. A cryptic sensor for HIV-1 activates antiviral innate immunity in dendritic cells. Nature.;467(7312):214-7. 
2. Waibler Z, et al., 2009. Vaccinia virus-mediated inhibition of type I interferon responses is a multifactorial process involving the soluble type I interferon receptor B18 and intracellular components. J Virol.;83(4):1563-71.
3. Warren L, et al., 2010. Highly efficient reprogramming to pluripotency and directed differentiation of human cells with synthetic modified mRNA. Cell Stem Cell.; 7(5):618-30.
4.Symons JA, et al., 1995. Vaccinia virus encodes a soluble type I interferon receptor of novel structure and broad species specificity. Cell.;81(4):551-60.
5. Colamonici OR, et al., 1995. Vaccinia virus B18R gene encodes a type I interferon-binding protein that blocks interferon alpha transmembrane signaling. J Biol Chem. ;270(27):15974-8.
6. Kim YG, et al., 2017. Recombinant Vaccinia virus-coded interferon inhibitor B18R: Expression, refolding and a use in a mammalian expression system with a RNA-vector. PLoS One. ;12(12):e0189308.
7. Alcamí A, Symons JA, Smith GL, 2000. The vaccinia virus soluble alpha/beta interferon (IFN) receptor binds to the cell surface and protects cells from the antiviral effects of IFN. J Virol.;74(23):11230-9. 

Figures

Recombinant B18R is a potent inhibitor of human IFN-α. Increasing concentrations of recombinant B18R were incubated for 0 min, 15 min, or 1 hour with the recombinant human IFN-α2b (0.1 ng/ml) prior to the addition of HEK-Blue™ IFN-α/β cells. After overnight incubation, SEAP activity in the cell culture supernatant was assessed using QUANTI-Blue™ Solution. Data are shown in percentage (%) of neutralization.

Enhanced mRNA transfection in THP-1 cells using B18R. The transfection efficacy of B18R (1 µg/ml) transfecting THP1-Dual™ cells with 100 ng of GFP mRNA using lipofection technology was assessed using flow cytometry. The percentage (%) of GFP-expressing and viable cells is shown.

Specifications

Class: Recombinant protein

Species:  Vaccinia Virus

Source: Chinese hamster ovary (CHO) cells

Tag: Hexahistidine (His6)

Solubility: 1 mg/ml

Working concentration: 0.1 - 10 ng/ml

Molecular mass: ~38 - 50 kDa, due to glycosylation

Tested application: Inhibition of human type I interferons (IFNs), modulation of mRNA transfection

Quality control: 

•  Purity: ≥95% (SDS-PAGE)
• The biological activity has been validated using cellular assays.
• The absence of bacterial contamination (e.g. lipoproteins and endotoxins) has been confirmed using HEK-Blue™ TLR2 and HEK‑Blue™ TLR4 cells.

Contents

Recombinant B18R protein is provided lyophilized, carrier-free, and provided in three quantities:

• inh-b18r: 25 μg
• inh-b18r-5: 5 x 25 μg
• inh-b18r-20: 500 μg

Note: This product is available in bulk quantities. Please contact us.

 The product is shipped at room temperature.

Upon receipt, store lyophilized B18R at -20°C.