Poly(I:C) HMW - TLR3 Agonist

High molecular weight polyinosine-polycytidylic acid – TLR3 agonist

Polyinosinic-polycytidylic acid (i.e. poly(I:C)) is a synthetic analog of double-stranded RNA (dsRNA), a molecular pattern associated with viral infections. InvivoGen’s Poly(I:C) HMW (High Molecular Weight) is comprised of long strands of inosine poly(I) homopolymer annealed to strands of cytidine poly(C) homopolymer. The average size of Poly(I:C) HMW is from 1.5 kb to 8 kb. Poly(I:C) HMW is functionally validated for TLR3 potency using HEK-Blue™ TLR3 Cells and the absence of contaminants (e.g. lipoproteins and endotoxin) is confirmed using TLR2 and TLR4 cellular assays, respectively.

Poly(I:C) recognition and signaling

Poly(I:C) is structurally similar to dsRNA, present in some viruses, and is therefore commonly used to model the actions of extracellular dsRNA.

Upon binding to its receptors, poly(I:C) is able to selectively activate numerous signaling pathways depending on the conditions. Poly(I:C) is recognized by endosomal Toll-like receptor 3 (TLR3) [1, 2]. Upon recognition, TLR3 activates the transcription factor interferon regulatory factor 3 (IRF3), through the adapter protein Toll-IL-1 receptor (TIR) domain-containing adapter (TRIF, also known as TICAM-1) [3]. Activation of IRF3 leads to the production of type I IFNs (e.g. IFN-β). Additionally, recognition of poly(I:C) can lead to the recruitment of TNF receptor-associated factor 6 (TRAF6) or receptor-interacting protein 1 (RIP1), with the subsequent activation of the transcription factors NF-κB and AP-1 [4]. Activation of these pathways triggers the production of inflammatory cytokines and chemokines such as TNF-α, IL-6, and CXCL10. Furthermore, poly(I:C) may activate the cytosolic RNA helicases retinoic acid-inducible protein I (RIG-I) and melanoma differentiation-associate gene 5 (MDA-5) [5].

Due to its ability to induce signaling via multiple inflammatory pathways, poly(I:C) is known to increase vaccine immunogenicity, especially in formulations that target dendritic cells. It has been shown that the superior qualities of poly(I:C) as a vaccine adjuvant may be due to synergy between TLR3 and MDA-5 activation [6]. 

Key features of Poly(I:C) HMW:

• Potent activator of TLR3
• Functionally validated
• Highly cited in the literature for both in vitro and in vivo assays
• Pre-labeled and guaranteed sterile VacciGrade™ Poly(I:C) HMW forms are also available

References:

1. Alexopoulou L. et al., 2001. Recognition of double-stranded RNA and activation of NFkappaB by Toll-like receptor 3. Nature 413(6857):732-8.
2. Matsumoto M. et al., 2002. Establishment of a monoclonal antibody against human Toll-like receptor 3 that blocks double-stranded RNA-mediated signaling. BBRC. 293(5):1364-9.
3. Yamamoto M. et al., 2003. Role of Adaptor TRIF in the MyD88-Independent Toll-Like Receptor Signaling Pathway. Science. 301:640.
4. Kawai T & Akira S., 2008. Toll-like receptor and RIG-I-like receptor signaling. Ann N Y Acad Sci. 1143:1-20. Review.
5. Kato H. et al., 2006. Differential roles of MDA5 and RIG-I helicases in the recognition of RNA viruses. Nature 441(7089):101-5.
6. van den Boorn, J.G. et al. 2012. Nucleic acid adjuvants: toward an educated vaccine. Adv Immunol. 114:1-32.