Electric pulses increase the immunogenicity of an influenza DNA vaccine injected intramuscularly in the mouse

Vaccination by intramuscular injection of naked DNA is very efficient in th e mouse, but immunogenicity of DNA vaccines needs to be improved in man. Th e aim of our study was to determine in BALB/c mice if suitable electric pul ses delivered to the muscle after DNA injection - a procedure called electr otransfer - could improve the immunogenicity of suboptimal doses of a DNA v accine expressing the influenza hemagglutinin protein. The results show a s ignificant enhancement of the cellular and antibody responses following ele ctrotransfer for the 1- and 10-mug DNA doses, respectively, but no effect o n a lower dose. At the 10-mug dose, the IgG and hemagglutination inhibition mean titres were increased 25-fold and the inter-individual variability wa s markedly reduced. (C) 2001 Elsevier Science Ltd. All rights reserved.