Approach Example
Modification of plasmid design Promoter/enhancer elements
  Polyadenylation sequence
  Kozak sequence
  Secretory leader sequence
  Consensus sequence
  Codon optimization
Delivery methods Electroporation
  DNA tattoo
  Gene Gun
  Polyethylenimine (PEI) and Vaxfectin®
Adjuvants Plasmid unmethylatedCpG motifs
  TLR agonists
  Genetic adjuvants (e.g. cytokines/chemokines)
  Glycoprotein D of Herpes Simplex Virus (HSV)
  Chemical Compounds (e.g. bupivacaine)
Targeting to dendritic cells DEC205 receptor
  CD11c receptor
Heterologous prime-boost DNA prime followed by boost with recombinant attenuated viruses (e.g. MVA)
  DNA prime followed by boost with recombinant proteins
TLR: Toll Like Receptor
PD1: Programmed Cell Death 1
MVA: Modified Vaccinia Virus Ankara
Table 2: Strategies to enhance the potency of DNA vaccines.