Poly(I:C) (HMW) VacciGrade™ - TLR3-based Adjuvant

Polyinosinic-polycytidylic acid (poly(I:C)) is a synthetic analog of double-stranded RNA (dsRNA), a molecular pattern associated with viral infections.

Poly(I:C) can activate the immune response through two distinct pathogen recognition receptors (PRRs)  [1]. Endosomal poly(I:C) activates TLR3 while cytosolic poly(I:C) activates RIG-I/MDA-5.

Triggering the TLR3 pathway induces IL-12 and type I IFNs production, and improves MHC class II expression and cross-presentation of antigen  [1].

Stimulation of MDA-5 enhances the production of type I IFNs that play a critical role in enhancing T and B cell immunity  [1]. Poly(I:C) promotes Th1 (cellular) biased immunity through its induction of IL-12 and type I IFNs [1].

Poly(I:C) has been tested as an adjuvant in numerous animal models  [2-9]. Promising results have been obtained using poly(I:C) as an adjuvant in flu vaccine delivered intranasally to mice [2].

Poly(I:C) has also been shown to enhance the efficacy of peptide-based cancer vaccines by promoting tumor-specific T-cell responses in mice  [3-6].

Immunization of mice with poly(I:C) resulted in a strong Th1 response  [7] and high levels of serum type I IFN [8]. 

1. Coffman R.L. et al., 2010. Vaccine adjuvants: Putting innate immunity to work. Immunity 33(4):492-503.
2. Ichinohe T. et al., 2005. Synthetic double-stranded RNA poly(I:C) combined with mucosal vaccine protects against influenza virus infection. J Virol. 79(5):2910–2919.
3. Pulko V. et al., 2009. TLR3-stimulated dendritic cells upregulate B7-H1expression and influence the magnitude of CD8 T cell responses to tumor vaccination. J Immunol 183(6):3634–3641.
4. Currie A.J. et al., 2008. Targeting the effector site with IFN-alpha beta-inducing TLR ligands reactivates tumor-resident CD8 T cell responses to eradicate established solid tumors. J Immunol 180(3):1535–1544.
5. Salem M.L. et al., 2005. Defining the antigen-specific T-cell response to vaccination and poly(I:C)/TLR3 signaling: evidence of enhanced primary and memory CD8 T-cell responses and antitumor immunity. J Immunother 28(3):220–228.
6. Celis E. 2007. Toll-like receptor ligands energize peptide vaccines through multiple paths. Cancer Res. 67(17):7945–7947.
7. Fransen F. et al., 2007. Agonists of Toll-like receptors 3, 4, 7, and 9 are candidates for use as adjuvants in an outer membrane vaccine against Neisseria meningitidis serogroup B. Infect Immun 75: 5939-46.
8. Longhi M.P. et al., 2009. Dendritic cells require a systemic type I interferon response to mature and induce CD4+ Th1 immunity with poly IC as adjuvant. J Exp Med 206: 1589-602.
9. Stahl-Hennig C. et al., 2009. Synthetic double-stranded RNAs are adjuvants for the induction of T helper 1 and humoral immune responses to human papillomavirus in rhesus macaques. PLoS Pathog 5:e1000373.