Electroporation-based DNA transfer enhances gene expression and immune responses to DNA vaccines in cattle

Despite the potential of DNA vaccines to induce strong, balanced immune responses in small experimental species, the immune responses to DNA immunization in larger species have generally been moderate and inconsistent. In this study, the TriGridtrade mark Delivery System (TDS), an electroporation-based DNA delivery platform, was evaluated for administration of DNA vaccines to calves. When compared to conventional intramuscular delivery, TDS-based delivery markedly and consistently enhanced gene expression from a plasmid encoding a reporter gene, secreted alkaline phosphatase, and improved cell-mediated and humoral immune responses to a plasmid encoding a model antigen, hepatitis B surface antigen. Importantly, the TDS-based procedure was well tolerated by the calves, which did not need to be anesthetized or sedated. These results suggest that the TDS is a useful delivery method for DNA vaccines in cattle.