Moderate Heat-Assisted Gene Electrotransfer for Cutaneous Delivery of a DNA Vaccine Against Hepatitis B Virus

Abstract

An estimated 350 million people are living with chronic Hepatitis B virus (HBV) worldwide. Preventative HBV vaccination in infants has reduced the disease burden; however, insufficient immunization programs and access obstacles leave vulnerable populations at risk for infection in endemic regions. Gene electrotransfer (GET) using a noninvasive multielectrode array (MEA) provides an alternative platform for DNA vaccination in the skin. DNA vaccines are nonlive and nonreplicating and temperature stable unlike their counterparts. In addition, their simple engineering allows them to be manufactured quickly at a low cost. In the current work, we present the combination of GET and moderate heating for delivery of a DNA vaccine against HBV. Our laboratory has previously shown the synergy between moderate tissue preheating at 43°C and GET with the MEA as a means to reduce both the applied voltage and pulse number to achieve similar if not higher gene expression than GET alone. In this study, we expand upon this work, by optimizing the plasmid dose to achieve the highest level of expression. Using the reporter gene luciferase, we found that an intradermal injection of 100 lL at 1 mg/mL induced the highest expression levels across all tested GET conditions. We then evaluated our moderate heat-assisted GET platform for the intradermal delivery of a plasmid encoding Hepatitis B surface antigen (pHBsAg) via a prime and prime plus boost vaccination protocol. At 18 weeks, following the prime plus boost protocol, we observed that a high-voltage low-pulse GET condition with moderate heating (45 V 36 p+heat) generated antibodies against Hepatitis B surface antigen (HBsAb) at peak measuring 230-fold over injection of plasmid DNA alone with moderate heating. HBsAbs remained robust over the 30-week observation period. These data suggest that moderate heatassisted GET has the potential to induce strong immune responses, an attractive feature for development of an alternative vaccine delivery platform.

Moderate Heat-Assisted Gene Electrotransfer as a Potential Delivery Approach for Protein Replacement Therapy through the Skin

“…After 18 weeks following a high-voltage high-pulse GET protocol with moderate heating (45 V 36p + heat), antibody titers were 230-fold higher than a moderately heated injection only control. Antibodies against Hepatitis B surface antigen remained elevated for 30 weeks following a prime pulse boost vaccination protocol with this platform [80]. These results combined with the Factor IX protein replacement therapy presented here, suggest there are a myriad of applications moderate heating could assist in enhancing the utility of current GET protocols.…”

“…Moreover, alternative therapeutic purposes where smaller amounts or weight of product are needed, such as growth hormone delivery, could also be an appropriate application for this technology [78,80,81]. An infrared laser was chosen as the heating source in this case due to its speed and precision at which the target temperature could be reached and specifically applied.…”

Advanced micro/nano-electroporation for gene therapy: recent advances and future outlook

“…This effectively stimulates a stronger immune response, thereby greatly enhancing the vaccine's effectiveness and bringing about a revolutionary breakthrough in the field of vaccines. [121][122][123] Table 2 provides an overview of the current practical applications of GET in vaccines, showcasing its outstanding performance in enhancing vaccine efficacy. Through the application of GET technology, it is expected that more efficient and safe vaccines can be developed, making a significant contribution to the field of human health.…”