BACKGROUNDAlzheimer's disease (AD) is a neurodegenerative disorder characterized by overproduction of beta-amyloid (Abeta), with the subsequent pathologic deposition of Abeta which is important for memory and cognition. Recent studies showed murine models of AD and AD patients inoculated with Abeta(1-42) peptide vaccine had a halted or delayed pathological progression of AD. Unfortunately, the clinical phase IIa trial of Abeta(1-42) peptide vaccine (AN1792) was halted prematurely because of episodes of menigoencephalitis in 18 of the vaccinated patients. The vaccination of BALB/c or Tg2576 transgenic mouse with Abeta(1-15) peptide vaccine is safe and the immune effects are satisfactory. This study further characterizes the specific humoral immune responses in adult rhesus monkeys induced by Abeta(1-15) peptide vaccine.

METHODSFive male adult rhesus monkeys were injected intramuscularly with Abeta(1-15) peptide vaccine at baseline and at weeks 2, 6, 10, 14, 18 and 22. The titers and IgG isotypes of the antibody against Abeta(1-42) in serum was measured by Enzyme-linked Immunosorbent Assay (ELISA). The specificity of the antibody against Abeta(1-42) was determined by Western blot. The Abeta plaques in Tg2576 transgenic mouse brain were stained with the antiserum using immunohistochemistry method.

RESULTSAt the eighth week after the vaccination, antibody against Abeta(1-42) began to develop significantly in serum. The titers of the antibody increased following vaccine boosted and reached 1:3840 at the twenty-fourth week, then decreased after the termination of inoculation. The IgG1 was accounted for the highest level in the antiserum pool. The antibody against Abeta(1-42) showed high specificity. The Abeta plaques in Tg2576 transgenic mouse brain were labeled with the antiserum.

CONCLUSIONAbeta(1-15) vaccine can induce vigorously specific humoral immune responses in adult rhesus monkey.