ODN 1668 sodium is a B class CpG ODN (oligodeoxynucleotide) recognized as a TLR-9 agonist. It demonstrates potent immunomodulatory effects by enhancing the level of IgG2 subtype antibodies and stimulating both T cell and B cell immune responses, making it useful for vaccine adjuvant research. Additionally, CpG ODN 1668 sodium induces antibacterial immune responses in orange-spotted grouper through a CaTLR9-dependent pathway. Sequence: 5’-tccatgacgttcctgatgct-3’.