CpG-B DNA, Rat

The rat CpG-B DNA belongs to the class of CpG-B oligodeoxynucleotides (ODN), also known as ‘K’-type ODN, with a full phosphorothioate (PS) backbone. It is particularly effective for activating B cells. The vertebrate immune system has evolved innate immune defense pattern recognition receptors (PRRs) that detect unmethylated cytosine-phosphate-guanine (CpG) motifs within bacterial DNA. Cellular activation by CpG motifs occurs via the Toll signal pathway. The Toll-like receptor-9 (TLR9, CD289) appears to be a major component of the CpG-DNA receptor, acting by direct binding to CpG-DNA, which triggers the induction of cell signaling pathways including the mitogen activated protein kinase (MAPKs) and NFκB, leading to stimulation of various cells of the immune system. The human TLR9 is expressed in B cells and plasmacytoid dendritic cells (PDC). Mice also express TLR9 in the myeloid compartment. Optimal sequences for activating TLR9 vary among species. Synthetic ODN contain CpG-DNA motifs mimicking the immunostimulatory effects of bacterial DNA and can, therefore, be used as immunoprotective agents, vaccine adjuvants and anti-allergic agents. CpG ODN also affects immune tolerance and autoimmunity. Different classes of CpG ODN are characterized each with distinct effects on the immune response: CpG-A (‘D’-type), CpG-B (‘K’-type), and CpG-C. CpG-B ODN are characterized by a full phosphorothioate backbone with one or more CpG motifs without poly -G motifs. CpG-B ODN are weak inducers of IFN-alpha but are very potent Th1 adjuvants and strong B cell response stimulators. CpG-B ODN promote survival, activation, and maturation of both monocyte derived dendritic cells and PDC. This CpG-B is a 22-mer that is able to modulate the immune response in rat. It has the following sequence: 5′-tgactgtgaacgttcgagatga-3′. Regular letters represent phosphorothioate linkage and bold letters represent CpG dinucleotides.