Augmented humoral and cellular immune response of hepatitis B virus DNA vaccine by micro-needle vaccination using Flt3L as an adjuvant

The purpose of this work was to assess the immune response against plasmid DNA encoding hepatitis B virus (HBV) HBsAg in C57BL/6 mice inoculated by micro-needle. Fms-like tyrosine kinase 3 ligand (Flt3L), a hematopoietic growth factor, was used as an adjuvant. Immune response was determined by analysis of cytokine production. In addition, cytotoxic lymphocyte (CTL) activity was measured 7 days after in vitro addition of tumor cells (CT26/S) stabling expressing HBsAg. The efficacy of immunoprotection against CT26/S was determined by antibody response to this challenge. A strong antibody response was induced by inoculation with the DNA vaccine via micro-needles assisted with Flt3L, Administration of the vaccine to splenocytes induced significantly higher levels of interleukin-12 and gamma interferon. CTL response to the vaccine was stronger than that stimulated by intramuscular or micro-needle injections alone. Our study suggests useful strategies for improving the efficacy of vaccines against HBV and other pathogens.