The potential of CpG oligodeoxynucleotides as mucosal adjuvants

The development of mucosal vaccines for humans has been hindered by the lac k of safe yet effective mucosal adjuvants. Bacterial toxins are commonly us ed as adjuvants in animal models, but they are too toxic for use in humans. A novel class of adjuvant is CpG DNA, which contains unmethylated CpG dinu cleotides in particular base contexts (CpG motifs). CpG DNA is most often c oadministered with antigen in the form of synthetic oligodeoxynucleotides ( CpG ODN), which are made with a nuclease-resistant phosphorothioate backbon e. The vast majority of studies using CpG DNA as adjuvant have been with pa renteral delivery; recently, however, mucosal immunization with CpG DNA as adjuvant has also been shown to induce both systemic (humoral and cellular) and mucosal antigen-specific immune responses. This review will highlight the recent uses of CpG DNA as an adjuvant at mucosal surfaces.