DNA-mediated vaccines consist of plasmid DNA that contains an inserted sequence encoding an immunogenic protein of a target pathogen. In this study, the humoral immune response to DNA-mediated vaccines was evaluated by vaccination with a - galactosidase reporter DNA vaccine in both tilapia (Oreochromis niloticus) and Atlantic bottlenose dolphins (Tursiops truncatus). Neither aquatic species elicited a measurable humoral immune response to the experimental vaccine using test procedures. Studies for alternative reporter genes and methods of optimized vaccination are currently underway. Finally, a specific DNA-mediated vaccine was engineered and tested for expression of dolphin morbillivirus (DMV) genes. The hemagglutinin and fusion proteins of DMV were amplified and cloned into a eukaryotic expression vector that was shown to transcribe mRNA specific to each gene. Documenting that the transfected cells are secreting proteins will require further research.