453. Protection Against Lethal Dengue Challenge By IM Delivery of Synthetic, EP-Delivered DNA Encoding Designed Anti-Dengue Neutralizing Antibodies

Dengue virus (DENV) is the most important mosquito-borne viral infection in humans, with nearly 400 million infections occurring each year and a continually expanding geographic reach. While vaccines are being developed, none are currently available that provide balanced protection against all DENV serotypes. Advances in human antibody isolation have uncovered DENV neutralizing antibodies (nAbs) that are capable of preventing infection from multiple serotypes. Yet delivering monoclonal antibodies using conventional methods is impractical due to high costs. Engineering nucleic acid-based strategies for delivering monoclonal antibodies could tip the scale in the fight against DENV, as well as other emerging infectious diseases.Here, we describe an approach to delivering cross-reactive neutralizing antibodies against DENV into the host circulation using DNA plasmid-mediated antibody gene transfer. This approach, which we term DNA mAb (DMAB) delivery, generates biologically relevant levels of mAbs after a single intramuscular injection of antibody-encoding DNA followed by in vivo electroporation (EP). Since this approach allows for genetic tailoring of the exact features of the desired antibody, we incorporated Fc region modifications to a naturally occurring human anti-DENV neutralizing antibody to enhance antibody function in vivo. We demonstrate that intramuscular delivery in mice of pDVSF-3 LALA, which encodes a human anti-DENV1-3 IgG1 neutralizing antibody modified with a mutation that abrogates FcgR binding, produces anti-DENV antisera capable of binding and neutralizing DENV1-3. Importantly, mice receiving pDVSF-3 LALA, but not the unmodified pDVSF-3 WT, were protected from both virus-only disease and antibody-enhanced lethal disease. These data establish this novel platform as a safe, effective means of delivering protective monoclonal antibodies to a host.This work was supported by grants funded to DBW through the National Institutes of Health, the DARPA-PROTECT award, and Inovio Pharmaceuticals Inc.