CpG Oligodeoxynucleotides

CpG oligodeoxynucleotides (ODN) are short, single-stranded DNA molecules containing a high percentage of CpG motifs. Their backbone is partially or completely phosphothioated. ODNs whose CpG motifs are unmethylated are recognized by pattern recognition receptors (PRRs) like Toll-like receptor 9 (TLR9) and therefore act as immunostimulants. CpG oligodeoxynucleotides induce cytokine and interferon production as well as maturation and activation of B-cells, monocytes, NK-cells and plasmocytoid dendritic cells. Hence, CpG oligodeoxynucleotides are used as adjuvants and in cancer therapy. In contrast, ODNs containing a TTAGGG-motif are TLR9 antagonists and have immunosuppressive effects.