Sometimes in life science, simple research strategies often provide the basis for new therapeutic approaches. For HIV, the development of safe and effective vaccines has proven to be challenging. However now, investigators from The Wistar Institute are drawing inspiration from a commonly used laboratory technique called electroporation to aid in constructing complex therapeutics for infectious agents, as well as for diverse implications in therapeutic delivery. In a new study, the scientists applied synthetic DNA technology to engineer a novel eCD4-Ig anti-HIV agent and to enhance its potency in vivo. Findings from the new study were published recently in EBio Medicine through an article titled “Synthetic DNA delivery by electroporation promotes robust in vivo sulfation of broadly neutralizing anti-HIV immunoadhesin eCD4-Ig.”
The Wistar team are exploring passive immunization of laboratory-produced immunoadhesins as well as traditional gene therapy methods for delivery of these complex therapeutic molecules. Immunoadhesins are designed antibody-like molecules specifically engineered to efficiently neutralize diverse forms of HIV by binding with high affinity to the virus envelope.
“These complex therapeutics are difficult to deliver through traditional strategies and achieving full activity in vivo using DNA technology is also challenging,” explains senior study investigator David Weiner, Ph.D., executive vice president, director of the Vaccine and Immunotherapy Center and W.W. Smith Charitable Trust Professor in Cancer Research at The Wistar Institute. “We demonstrated that a combination of plasmids could be designed to produce a novel protein as well as its modifying enzyme, allowing them to collocate with each other and create a highly functional immunoadhesin.”
Electroporation of synthetic DNA (DNA/EP) consists of the application of small, controlled directional electric currents into the skin or muscle to facilitate optimal uptake of DNA molecules and local production of the DNA-encoded proteins. Using this technology, Dr. Weiner and his colleagues were able to achieve robust and long-term in vivo expression. A single injection of the synthetic DNA formulation produced functional eCD4-Ig for several months in a mouse model.
“With a single round of DNA injection, a peak expression level of 80-100 μg/mL was observed in mice 14 days post injection,” the authors wrote. “The engineered IgE-TPST2 enzyme trafficked efficiently to the Trans-Golgi Network (TGN). Co-administrating low dose of plasmid IgE-TPST2 with plasmid eCD4-Ig enhanced the potency of eCD4-Ig by three-fold in the ex vivo neutralization assay against the global panel of HIV-1 pseudoviruses.”
Previous studies have shown that a modification of immunoadhesins, called sulfation, favors their binding to the HIV envelope—therefore, co-expression of the TPST2 enzyme that operates this modification is necessary to enhance the anti-HIV potency of the produced eCD4-Ig. The Wistar team proved the ability of synthetic DNA to encode the TPST2 enzyme as well as the instructions to direct the produced TPST2 to the cell compartment where the eCD4-Ig molecule is manufactured. The combined delivery resulted in the production of sulfated eCD4-Ig immunoadhesins that exhibited enhanced potency.
Collectively, these study results provide an important advancement for the field of HIV immunization and open the path to further applications for in vivo delivery of biologics.
“This is the first report on the use of synthetic DNA to encode an enzyme that can effectively carry out its activity and modulate biological functions of a target protein with high efficiency in vivo,” Dr. Weiner concludes.