Abstract: CpG motifs containing cytosine-guanosine dinucleotides are prevalent in the genomes of most bacteria and DNA viruses. As one of the pathogen-associated molecular patterns (PAMPs), CpG oligodeoxynucleotides (CpG ODN) contained CpG motifs are able to activate many kinds of immune cells, and trigger immune responses that are in favor of Th1 cell immunity. In mammalian cells, the recognition of CpG motifs is mediated by Toll-like receptor 9, which belongs to the Toll-like family of receptors (TLRs). TLR9-mediated immune activation has great potential use in the prevention of infectious diseases, and the development of novel vaccine adjuvants and the treatment of allergic diseases and cancer.

Key words: CpG motif; pathogen-associated molecular pattern (PAMP); Toll-like receptor