A construction of scFv. (A): Schematic representation of scFv gene construction using overlapping PCR. The variable regions of heavy chain (VH) and light chain (VL) were amplified separately by the 1st PCR. The VH and VL segments were assembled by the second overlap PCR to generate the scFv fragment. (B): Agarose gel analysis of PCR product of scFv. Lane M, DNA marker (100 bp ladder); lane 1, the scFv PCR products; lane 2, negative control (without templates).