Toll-like receptor 3 (TLR3) recognizes double-stranded RNA (dsRNA), a PAMP associated with viral infection.
The ligand of choice for TLR3 is a synthetic analog of dsRNA known as polyinosinic-polycytidylic acid (poly(I:C) or poly(rI):poly(rC)). Poly(I:C) comprises a strand of inosine poly(I) homopolymer annealed to a strand of cytidine poly(C) homopolymer. Poly(I) and poly(C) are prepared by enzymatic synthesis of IDP or CDP with polynucleotide phosphorylase (PNPase). Since each strand is synthesized enzymatically the size of each, and of the annealed product, can vary significantly.
InvivoGen is the only company to provide poly(I:C) in two different sizes:
- Poly(I:C) high molecular weight (HMW): average size of 1.5-8 kb.
- Poly(I:C) low molecular weight (LMW): average size of 0.2-1 kb
InvivoGen also provides poly(I:C) in biotin and fluorescently-labeled forms, in VacciGrade™ form (certified sterile and endotoxin-free per LAL validation), as well as a synthetic dsRNA analog, polyadenylic–polyuridylic acid (poly(A:U)), which signals exclusively through TLR3.
InvivoGen synthetic dsRNA analogs are functionally validated for TLR3 potency using HEK-Blue™ TLR3 Cells and are certified to be free of microbial contaminants (e.g. endotoxin or bacterial-membrane components) that can activate other TLR receptors, such as TLR2 or TLR4.