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DNA vaccines have failed so far in human trials because we have been
injecting them in the wrong place, say Swiss researchers. The vaccines contain
DNA that codes for proteins from viruses or tumours. Cells take up the DNA and
make the protein, hopefully triggering effective immunity, but results in people
have been disappointing. Now scientists working on mice at the University
Hospital in Zurich report in a future edition of Proceedings of the National
Academy of Sciences that putting DNA from a meningitis virus directly into
the spleen or lymph nodes—organs which help organise immunity—is a
thousand times more effective than injecting into skin or muscle.