Project summary/Abstract Alzheimer?s disease (AD) is the most common form of dementia found in the elderly and disease progression has been strongly associated with accumulation of Amyloid beta 1-42 (A?42) in brain. An immune-mediated approach as a preventive intervention to reduce amyloid plaques without causing brain inflammation is highly desirable for future clinical use. Genetic immunization, in which the immunizing agent is DNA encoding A?42, has great potential because the immune response to DNA is generally non-inflammatory, and differs quantitatively and qualitatively from the immune response elicited by peptides, which is mainly inflammatory. DNA immunization has historically been proven difficult to apply to larger mammals. A potential barrier to use DNA immunization in large mammals is the method for delivery of the DNA antigen. Over the last decade, substantial progress has been made to increase the effectiveness of DNA delivery and immune responses, respectively. Electroporation had been shown to greatly enhance DNA immunogenicity in clinical trials, and DNA electroporation has been reported as highly tolerable by the patients with few side effects. This proposal is aimed at translating our established gene gun DNA A?42 delivery immunization approach in mice into the clinically more feasible method of needle-free intradermal DNA delivery via jet injection possibly in combination with electroporation to trigger DNA uptake and immune responses. We will use wild-type mice and New Zealand White rabbits as a large mammal model to test our DNA A?42 delivery methods, and to demonstrate antibody production and safe immune responses. We will use the 3xTg-AD mouse model to demonstrate that DNA A?42 immunization using jet injection and/or electroporation is effective to break tolerance against self-antigens, leading to the production of sufficient anti-A?42 antibody levels to clear A?42 and prevent amyloid accumulation in the brain without causing inflammatory side effects. This study is designed to optimize the DNA delivery for possible testing in human trials.