Background: Recombinant antibodies are new versions of monoclonal antibodies that are produced by recent molecular biology techniques. These antibodies can be isolated by phage display technology from immune or non-immune libraries. Recombinant antibodies are applied to treatment of some diseases and also are increasingly used for diagnosis and detection of many antigens. In the latter case, the presence of antigen-antibody complexes has to be detected by further approaches. The aim of current research was to stain an anti-K99 phage antibody with two different protein dyes and to apply them directly for detection of E. coli K99 fimbriae.
Methods: In order to stain above antibody, a phagmid vector carrying the anti-K99 single-chain Fv (scFv) antibody was isolated, purified and transformed into TG1 strain of E. coli. Afterward, the antibody was expressed in this cell as phage-scFv antibody. Phage antibodies were subsequently eluted, purified and stained with Disperse Red dye 60 and Coomassie Brilliant Blue. Finally, the binding activity of coloured phage antibodies towards the purified K99 fimbriae was verified by immunoblotting.
Results: The results showed that anti-K99 phage antibody was stained with both dyes and the coloured phages were able to recognize the corresponding antigen.
Conclusions: These protein stains that they usually do not alter the protein structure can be used for staining phage antibodies. The coloured phage antibodies retain their binding affinity for the antigens, and therefore can be applied to detection of relevant antigens.