Identification and mapping of linear antigenic determinants of human amyloid ß(1-42) peptide.

Accumulation of cytotoxic oligomers of amyloid ß (Aß) is one of the major pathological hallmarks of Alzheimer's disease (AD). Several immunological approaches that prevent the conversion of Aß into its toxic form or that accelerate its clearance are being actively pursued worldwide. As part of these attempts, we have carried out sequential epitope analysis of Aß where antibodies raised against native Aß and its homologue Aß-KEK were screened for binding to five overlapping hexadecapeptides encompassing the full length of Aß sequence with 10 amino acid overlap. By this approach, we could identify a neutralizing epitope spanning the region 13-28 in Aß. These results demonstrate the presence of an additional stretch of Aß that can serve as mini-vaccine for AD.

Enhanced Th2 immunity after DNA prime-protein boost immunization with amyloid beta (1-42) plus CpG oligodeoxynucleotides in aged rats.

Generation and accumulation of fibrillar amyloid beta (Abeta) is widely considered as the pathogenic basis of neurodegeneration in Alzheimer's disease (AD). Both active immunization with fibrillar Abeta and passive immunization with anti-Abeta antibodies in transgenic mouse models of AD result in prevention/dissociation of Abeta plaque formation and restoration of cognitive functions. However, similar immunization studies in humans had to be halted because 6% of the AD patients developed acute meningoencephalitis, likely due to anti-Abeta specific autoimmune Th1 cells. Hence, making Abeta immunotherapy successful requires production of strong antibody responses without Th1-type immunity. In an attempt to develop safer vaccines, we examined the influence of oligodeoxynucleotides as adjuvant on the Th1 and Th2 immune response to Abeta in aged rats. We further investigated whether a DNA prime-protein boost strategy could elicit a more robust Th2 response. The results of the present study showed that all the animals injected with either Abeta peptide alone or Abeta encoding plasmid alone or plasmid DNA prime followed by peptide boost have elicited specific anti-Abeta antibodies. When co-administered, synthetic oligodeoxynucleotides (ODN) further enhanced the anti-Abeta titres. More importantly, the IgG subclasses of the antibodies generated by DNA prime-peptide boost regimen with ODN as adjuvant were primarily of IgG2b and IgG1 isotypes, suggesting that heterologous immunization strategy along with ODN would be advantageous in eliciting more beneficial Th2-type humoral immune response.