Successful adjuvant-free vaccination of BALB/c mice with mutated amyloid β peptides

Background: A recent human clinical trial of an Alzheimer's disease ( AD) vaccine using amyloid beta (A beta) 1-42 plus QS-21 adjuvant produced some positive results, but was halted due to meningoencephalitis in some participants. The development of a vaccine with mutant A beta peptides that avoids the use of an adjuvant may result in an effective and safer human vaccine. Results: All peptides tested showed high antibody responses, were long-lasting, and demonstrated good memory response. Epitope mapping indicated that peptide mutation did not lead to epitope switching. Mutant peptides induced different inflammation responses as evidenced by cytokine profiles. Ig isotyping indicated that adjuvant-free vaccination with peptides drove an adequate Th2 response. All anti-sera from vaccinated mice cross-reacted with human A beta in APP/PSI transgenic mouse brain tissue. Conclusion: Our study demonstrated that an adjuvant-free vaccine with different A beta peptides can be an effective and safe vaccination approach against AD. This study represents the first report of adjuvant-free vaccines utilizing A beta peptides carrying diverse mutations in the T-cell epitope. These largely positive results provide encouragement for the future of the development of human vaccinations for AD.