TLR agonists as vaccine adjuvants

Abstract

Despite the development of numerous successful vaccines, there are many pathogens for which a vaccine does not exist. In addition, it is clear that cancer vaccines will require novel adjuvants. Currently a number of non-live vaccines are being evaluated in order to address adverse events associated with live vaccines, however many of these have been proven to be ineffective. The major problem with most protein, peptide, and DNA vaccines is that they are poorly immunogenic or elicit an inappropriate immune response, and don't provide protection against the infectious agent or cancers. Therefore novel adjuvants that boost the immune responses will be required to make these vaccines effective. Many of the effects induced through activation of toll-like receptors (TLRs) can have significant effects on adaptive immune responses. Since ligands have been identified for many TLRs, and activation of TLRs results in stimulation of antigen presenting cells and enhanced B cell and T cell activation, TLR agonists are considered promising vaccine adjuvant candidates. This chapter will focus on TLR agonists that are in development for use as vaccine adjuvants.