Production and characterization of monoclonal and recombinant antibodies against antimicrobial Sulfamethazine

Division of Applied Life Science, Graduate School of Gyeongsang National University, Jinju 660-701, Korea.
Journal of Microbiology and Biotechnology (Impact Factor: 1.53). 05/2007; 17(4):571-8.
Source: PubMed


A monoclonal antibody (mab) against the antimicrobial sulfamethazine was prepared and characterized by an indirect competitive enzyme-linked immunosorbent assay (IC-ELISA). Sulfamethazine in the range of 0.2 and 45 ng/ml could be determined with the mab by IC-ELISA. cDNAs encoding a variable heavy chain and variable light chain of the mab were cloned to produce recombinant antibodies using phage display technology. Following phage rescue and three rounds of panning, a single-chain variable fragment (scFv) antibody with high sulfamethazine-binding affinity was obtained. ELISA analysis revealed that scFv antibody and parent mab showed similar, but not identical, characteristics. The IC50 value by IC-ELISA with scFv antibody was 4.8 ng/ml, compared with 1.6 ng/ml with the parent mab. Performances of the assays in the presence of milk matrix were compared; the mab-based assay was less affected than the scFv-based assay. Sixty milk samples were analyzed by mab-based IC-ELISA, and four samples were sulfamethazine positive; these results were favorably correlated with those obtained by HPLC.

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Available from: Sang-Do Ha, Apr 19, 2015
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    • "ScFv is a protein sequence that is generated through the fusion of the heavy chain variable domain (V H ) and the light chain variable domain (V L ) of an antibody. A scFv is more economically produced in Escherichia coli than intact immunoglobulins, which require a high-cost mammalian cell culture system (Fernandez, 2004; Yang et al., 2007). The expression of scFv in E. coli has generally been executed in an oxidizing compartment such as the periplasmic space instead of the reducing cytoplasm of wild-type E. coli because the typical scFvs require the formation of two conserved disulfide bridges for proper folding to occur (Glockshuber et al., 1992). "
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    ABSTRACT: Typically, single chain Fv antibodies are unable to fold properly under a reducing cytoplasm because of the reduction of disulfide bonds. The inability to fold limits both the production of the functional scFvs and their targeting against antigens, which are generally executed in a reducing cytoplasm. In this study, the target scFv CDR was grafted with stable human consensus framework sequences, which enabled the generation of a foldable scFv in a reducing cytoplasm of Escherichia coli. Additionally, the structural features affecting the folding efficiency of the engineered scFv were identified by analyzing the predicted structure. An anti-c-Met scFv, which was a cytoplasmic non-foldable protein, was redesigned as the model system. This study confirmed that the engineered anti-c-Met scFv was folded into its native form in the cytoplasm of E. coli BL21(DE3) without a significant loss in the specific binding activity against c-Met antigen. The structures of the wild-type anti-c-Met scFv and the engineered scFv were predicted using homology modeling. A comparative analysis based on the sequence and structure showed that the hydrophobicity of 12 solvent exposed residues decreased, and two newly formed salt bridges might have improved the folding efficiency of the engineered scFv under the reducing condition.
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    ABSTRACT: Single-chain Fv (scFv) antibody against c-Met is expected to be employed in clinical treatment or imaging of cancer cells owing to the important biological roles of c-Met in the proliferation of malignancies. Here, we show that the productivity of scFv against c-Met in Escherichia coli is significantly influenced by the orientation of its variable domains. We generated anti-c-Met scFv antibodies with two different domain orders (i.e., VL-linker-VH and VH-linker-VL), expressed them in the cytoplasm of E. coli trx/ gor deleted mutant, and compared their specific activities as well as their productivities. Productivity of total and functional anti-c-Met scFv with VH/VL orientation was more than five times higher than that with VL/VH format. Coexpression of DsbC enhanced the yield of soluble amounts of anti-c-Met scFv protein for both constructs. The purified scFv antibodies of the two different formats exhibited almost the same antigen-binding activities. We also compared the productivities and specific activities of anti-c-Met diabodies with VH/VL or VL/VH formats and obtained similar results to the case of scFv antibodies.
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