Figure 2.

Amyloid-β₄₂ (Aβ₄₂)–specific immune responses in BALB/c wild-type mice immunized with mouse Aβ₄₂ dimer gene vaccine. A, Western blot shows that all 3 mice in the vaccinated group produced specific anti-Aβ₄₂ antibodies that detected mouse recombinant glutathione S-transferase–Aβ₄₂ (GST-Aβ₄₂) dimers (lower arrow in lane P) and tetramers (upper arrow in lane P) (lanes m1, m2, m3). Mice in the control group (vector lacking Aβ gene) were negative (lane C). Recombinant GST-Aβ₄₂ protein in Escherichia coli extracts was shown in lane P stained with Coomassie blue. Serum samples were obtained 14 days after a third vaccination at 10-day intervals with dilution of 1:2000. kDa indicates kilodalton. B, Same serum samples as in A were tested by enzyme-linked immunosorbent assay for Aβ₄₂ peptide and show that all 3 mice (m1, m2, m3) vaccinated with Aβ₄₂ dimer gene showed specific antibody against human Aβ₄₂ peptide with 1:2000 dilution. C, Enzyme-linked immunospot assay demonstrated that no detectable cellular immune response was observed in Aβ₄₂ dimer gene–vaccinated mice. Concanavalin A (Con A) was added as a positive control. P–indicates no peptide added in peripheral blood T-cell culture; P+, a mixture of Aβ_9–18 and Aβ_1–42 peptide was added to the culture for 36 hours for specific antigen stimulation for T cells to release interferon-γ (INF-γ).