Induction of an immune response toβ-amyloid protein (Aβ) was reported to be effective in treating animal models of Alzheimer’s disease. Human clinical trials of vaccination with synthetic Aβ(AN1792), however, were halted due to brain inflammation, presumably induced by T cell-mediated immune responses.Therefore, to reduce the risk of an adverse T cell-mediated immune response to Aβimmunotherapy, we have designed a prototype epitope vaccines composed of 16 copies of Aβ1–9 fused with the immunoenhancement sequence (I) containing PADRE (pan-DR epitope) and TT (tetanus toxin epitope) sequences, which completely eliminates the autoreactive T cell responses and induces humoral immune responses againstβ-amyloid protein.The N terminal repeat sequence encoding the first nine amino acids of Aβ42 was obtained through PCR amplification and also the gene encoding the immunoenhancing sequence was synthesized by chemical methods, respectively. Then these genes were constructed into expression vectors to producepET-41b-(Aβ9)16, pGEX-4T-1-(Aβ9)16 and pGEX-4T-1-I-(Aβ9)16; Each expression vectors was transformed into E.coli.BL21(DE3), then was induced with IPTG to express the target recombinant protein. After affinity purification, the recombinant antigens GST-I-(Aβ9)16, GST-(Aβ9)16 and (His)6-(Aβ9)16 with over 95% purity were obtained;BALB/c mice were immunized with the three recombinant antigen proteins, respectively and the antisera were collected.ELISA results showed that much higher titers (1:6400 and 1:12800) against Aβ42 oligomers were observed in GST-(Aβ9)16 and GST-I-(Aβ9)16-induced antibodies. By comparing the process of changes in antibody titer, we found that GST-I-(Aβ9)16-induced[0] antibody quickly reached a satisfactory antibody titer. This result demonstrated that the immunoenhancing sequence (I) has a more remarkable capacity to enhance the immunoresponse ; the GST-I-(Aβ9)16, GST-(Aβ9)16, (His)6-(Aβ9)16 -induced antibodies showed a high specificity to Aβ42 monomers and oligomers, low to protofabrils but no specificity to mature fabrils. The cytotoxicity-neutralizing or cytotoxicity-inhibiting activities of antisera were assessed by MTT in PC12 cells. The results showed that all GST-I-(Aβ9)16, GST-(Aβ9)16 and (His)6-(Aβ9)16–induced antibodies have the abilities to inhibit or neutralize the cytotoxicity of Aβ42 oligomers and profibrils and the inhibiting effect is persistent during 30d. To confirm the results above, the inhibiting or inducing effect of antisera on Aβ42 aggregation or on the disassembly of Aβ42 fibrils in vitro were analyzed through electron microscopy observation. The results demonstrated that the three antibodies could not only stabilize Aβ42 in monomers but also completely prevent Aβ42 aggregation and fibrillogenesis.Taken together, the vaccines based on (Aβ9)16 generated a robust immune response and the antibodies exhibited the ability to inhibit and neutralize the cytotoxicity of Aβ42 both on the molecular level and the cellular level in this study. The (Aβ9)16 vaccine-based therapy might be potentially reliable and effective. These results will help lay the foundation for designing and developing the recombinant subunit vaccine to prevent and treat Alzheimer\'s disease.