Methods for rapid identification of a functional single-chain variable fragment using alkaline phosphatase fusion

Generation of scFv specific to human VEGFR-3 from the neutralizing mAb BDD073

In our previous study, we have produced a neutralizing mAb of vascular endothelial growth factor receptor 3 (VEGFR-3), specifically BDD073, which could inhibit angiogenesis in the CAM model. However, the clinical application of BDD073 is restricted due to its mouse origin, which might cause human anti-mouse antibody reactions. Herein, we generated functional recombinant single-chain variable fragments (scFv) from mAb BDD073 producing mouse hybridoma cells. The scFv gene containing variable regions of heavy and light chains of BDD073 was cloned into an expression vector with trx tag and expressed in Escherichia coli BL21 (DE3). The recombinant scFv was purified and refolded with Ni-NTA agarose metal affinity column. The bacterially expressed scFv showed moderate potency and specificity to the human VEGFR-3. It may serve as a potential candidate of anti-VEGFR3 treatment for biotechnological and therapeutic applications.

Identification of two aberrant transcripts derived from a hybridoma with amplification of functional immunoglobulin variable genes

Murine monoclonal antibodies (mAbs) are widely used but have limitations if administered in humans. The use of chimeric or humanized mAbs can reduce immunogenicity. The first step in producing such mAbs is to clone murine variable genes from a hybridoma, but it is possible to amplify both functional and aberrant variable genes, as they coexist in the hybridoma. During the development of a murine-human chimeric antibody, we have cloned from a hybridoma the functional heavy chain variable region (V(H)) and light chain variable region (V(L)) genes of a mAb that blocks the binding of anthrax lethal factor to protective antigen. In this study, we report the detection of two aberrant transcripts from a hybridoma produced using myeloma cell line OUR-1, the development of a method to distinguish between the functional and abundant aberrant V(L) transcripts, and the origins of these aberrant genes. The aberrant V(L) gene is derived from OUR-1 cells, while the aberrant V(H) gene might derive from antibody repertoires in B cells or from gene rearrangement in the hybridoma cells. The aberrant V(H) and V(L) genes in this study may facilitate discrimination between the functional and aberrant variable genes from hybridoma cells.