IC31

**IC31** is a fully synthetic, two-component vaccine adjuvant originally developed by Intercell and subsequently managed by Valneva. It combines the cationic antimicrobial peptide KLKL5KLK with ODN1a, a phosphodiester oligodeoxynucleotide containing repeating deoxyinosine-deoxycytosine motifs rather than CpG motifs. ODN1a activates endosomal Toll-like receptor 9 signaling through the MyD88 pathway, while KLKL5KLK promotes cellular uptake, intracellular delivery, and local antigen-adjuvant depot effects. IC31 enhances type 1 T-cell immunity, cytotoxic T-cell responses, antigen-specific antibody production, and type I interferon signaling when formulated with vaccine antigens. It has been evaluated clinically as the adjuvant component of tuberculosis subunit vaccines including H1:IC31, H4:IC31, and H56:IC31, with phase 2 tuberculosis studies and generally acceptable safety and reactogenicity reported.

Other names

IC31 adjuvantIC-31 adjuvantIC 31 adjuvant