752. Delivery of Non-Microparticle Naked DNA Vaccine Using Supersonic Flow by a Low-Pressure Gene Gun

Abstract

DNA vaccines are a new and powerful approach to generation of immunological responses against infectious disease and cancer. DNA can be delivered either into muscle by simple injection or into epidermal by gene gun. Intramuscular injection requires large amount of DNA (100microgram/per mouse) to elicit the immune response; in contrast, microparticlulate bombardment system can induce immune response using very low amount of DNA (1 microgram/per mouse). One disadvantage of gene gun bombardment is that non-biodegradable gold or tungsten may skew the immune response or cause adverse side effect when accumulated. In this report, we have demonstrated the direct delivery of naked DNA without any microparticle using a modified gene gun. The modified gene gun is based on the aerodynamic theory that a supersonic flow is generated when the pressure difference between the inside and the outside pressure of the nozzle is greater than 1.9atm. This high speed airflow can carry the particle from stationary state to accelerate to an extreme high speed (200m/sec). In this way, the naked DNA may be directly transformed into the mammalian cells. Previous study indicated that this modified gene gun achieve similar deliver efficacy as the gene gun commercially available using gold-coated DNA. In this report, we showed that the modified gene gun can achieve 10–40% delivery efficacy as the gold particle coated with DNA in Balb/C mice, C57BL/6 mice, and C3H mice using luciferase gene reporter driven by CMV promoter. Then, we examined the immune responses elicited by inoculation of DNA encoding HBV large surface protein expressed by its own promoter. The non-microparticle DNA and gold-coated DNA elicited similar humoral immunity as shown by antibody titer. Similar overall cytokine profile was induced by either type of DNA vaccine. Furthermore, we examined the therapeutic responses with the DNA vaccine against the extracellular domain of neu on the mouse tumor (MBT-2) naturally overexpressing neu in C3H mice. The results indicated that non-microparticle naked neu DNA vaccine can achieve similar anti-tumor effect as the gold-coated neu DNA vaccine in C3H mice at the dose of 1 microgram/per mouse. Ying-Chang Wang is an employee of BioWare Technologies Co., Ltd, Taipei, Taiwan.