Immunostimulatory effects of DNA and CpG motifs

More than a decade has passed since the first report claimed the immunostimulatory activity of microbial DNA. This property is not only restricted to microbial DNA since DNAs from a variety invertebrate organisms including nematodes, molluscs, yeasts and insects cause a mitogenic polyclonal activation of murine B cells and stimulate macrophages and NK cells. These impressive immunostimulatory properties result from six base motifs called CpG motifs or Immunostimulatory Sequences (ISS). In contrast to mammalian DNA, the CpG commonly found in invertebrate organisms are non-methylated. Recent developments have focused on the mechanisms responsible for CpG immunomodulatory activities and ways of using them as adjuvants for prophylactic or therapeutic vaccination against diseases and in cancer immune therapy.