A peptide prime-DNA boost immunization protocol provides significant benefits as a new generation Aβ42 DNA vaccine for Alzheimer disease

Immunotherapy has the potential to provide a possible treatment therapy to prevent or delay Alzheimer Disease. In a clinical trial (AN1792) in which patients received this immunotherapy and received active Aβ1–42 peptide immunizations, treatment was stopped when 6% of patients showed signs of meningoencephalitis. Follow up on these patients led to the conclusion that the antibody response was beneficial in removing Aβ1–42 from brain but an accompanying inflammatory Th1 T cell response was harmful. As a safe alternative treatment targeting the same self protein, Aβ1–42, in brain, we and others are working on a DNA Aβ1–42 immunization protocol as the immune response to DNA immunizations differs in many aspects from immunizations with peptide antigens. Because the immune response to DNA vaccination has different kinetics and has a significantly lower antibody production, we evaluated two different prime boost regimens, Aβ1–42 DNA prime/ Aβ1–42 peptide boost and Aβ1–42 peptide prime/ Aβ1–42 DNA boost for their effectiveness in antibody production and possible side effects due to inflammatory T cell responses. While both boost regimes significantly enhanced the specific antibody production with comparable antibody concentrations, the absence of the Aβ1–42 T cell response (no proliferation and no cytokine production) is consistent with our previous findings using this DNA Aβ1–42 trimer immunization and greatly enhances the safety aspect for possible clinical use.