Human single chain Fv antibodies and a complementarity determining region-derived peptide binding to amyloid-beta 1-42.

A library of phage-displayed human single-chain Fv (scFv) antibodies was selected against the human amyloid-beta peptide (Abeta42). Two new anti-Abeta42 phage-displayed scFvs antibodies were obtained, and the sequences of their V(H) and Vkappa genes were analyzed. A synthetic peptide based on the sequence of Ig heavy chain (V(H)) complementarity-determining region (HCDR3) of the clone with the highest recognition signal was generated and determined to bind to Abeta42 in ELISA. Furthermore, we showed for the first time that an HCDR3-based peptide had neuroprotective potential against Abeta42 neurotoxicity in rat cultured hippocampal neurons. Our results suggest that not only scFvs recognizing Abeta42 but also synthetic peptides based on the V(H) CDR3 sequences of these antibodies may be novel potential candidates for small molecule-based Alzheimer's disease (AD) therapy.

Amyloid-beta peptide-specific single chain Fv antibodies isolated from an immune phage display library.

A single-chain fragment variable (scFv) antibody library displayed on phage was constructed using spleen cells from mice immunized with human amyloid-beta peptide (Abeta42). This first anti-Abeta42 scFv immune antibody library was selected against human Abeta42. A number of positive clones were obtained, and sequences of VH and Vkappa genes were analyzed using ExPASy and BLAST computer tools. This analysis revealed that only two unique clones with identical VH and Vkappa complementarity determining region (CDR) (except HCDR2) and identical germline genes were selected, indicating that oligoclonal immune response was occurring in Abeta42-immunized mice. Abeta42-specific scFv antibodies selected from this first immune anti-Abeta42 phage antibody library may be an important tool for the development of therapeutic molecules for Alzheimer's disease (AD).