The success of naked DNA vaccines hinges on their ability to generate a potent immune response against a specified antigen. Although most companies, including Vical Inc. and PowderJect Pharmaceuticals plc, deliver their DNA vaccines intramuscularly or intradermally, a study in mice suggests plasmid DNA injected into the lymphoid tissue was more efficient in inducing cytotoxic T lymphocyte (CTL) responses.

Researchers at University Hospital in Zurich last week published data in the Proceedings of the National Academy of Sciences showing that plasmid DNA directly injected into the peripheral lymph node in mice is 100- to 1000-fold more efficient in producing specific CTL responses than intramuscular or intradermal administration. The plasmid DNA in the study encoded an epitope from the lymphocytic choriomeningitis virus (LCMV) glycoprotein, but the