Novel monoclonal antibody 3B8 specifically recognizes pyroglutamate-modified amyloid β 3-42 peptide in brain of AD patients and 3xTg-AD transgenic mice

In addition to the full-length beta-amyloid peptides (A beta 1-40/42), several A beta variants, truncated at their N- or C-termini and bearing different post-translational modifications, have been detected in the brain of Alzheimer's disease (AD) patients. A beta N3(pE), an A beta peptide bearing an amino-terminal pyroglutamate at position 3, is a significant constituent of intracellular, extracellular and vascular A beta deposits in brain tissue from individuals with AD and Down syndrome. Pioneering immunotherapy studies have primarily focused on the full-length A beta peptide, disregarding the presence of N-truncated/modified species. However, in recent years, increasing attention has been directed towards A beta N3(pE), in both pre-clinical studies and clinical trials. In the present study, we generated and characterized an anti-A beta N3(pE) mouse monoclonal antibody (3B8) that recognizes amyloid aggregates in brain tissue from AD patients and in 3xTg-AD transgenic mice. To identify the epitope recognized by 3B8, a library of random heptapeptides fused to the minor coat protein of M13 phage was screened. Results from screening, along with those from ELISA assays against distinct A beta fragments, suggest recognition of two conformational epitopes present in A beta N3(pE) and A beta 3-42, regardless of the glutamate-pyroglutamate modification. The novel 3B8 antibody may be useful in future therapeutic and diagnostic applications for AD.