Expression and purification of single-chain anti-HBx antibody in Escherichia coli

Monoclonal antibodies have been widely used in tumor targeting studies with promising results. However, their clinical application has been limited by heterogeneity and macro-molecular movement of murine antibody. In this study, the variable-region (heavy- and light-chain) fragments of anti-HBx monoclonal antibody were enriched by the polymerase chain reaction. The expression vector, which included a 6x histidine sequence in the 3' terminus of the HBx single-chain antibody (sFv) was recombined with a linker sequence (KLGGGGFSGA) between the variable regions. The expression product from Escherichia coli fused with 6xHis was purified by nickel (Ni2+) nitrilotriacetate chelating resin. The results of enzyme-linked immunosorbent assay and Western blotting showed that sFv had binding affinity with HBxAg, suggesting that it could become a novel targeting carrier in clinical trials.