a recombinant gene encoding a single - chain variable fragment antibody against venezuelan equine encephalitis virus being cloned into a prokaryotic t7 rna polymerase - regulated expression vector was disclosed . a streptavidin - binding peptide sequence fused to a 6his tag is then attached downstream to the scfv gene . the recombinant fusion protein is expressed in bacteria and then purified by immobilized metal affinity chromatography . elisa and western blotting results revealed that the fusion protein not only retained vee antigen binding and specificity properties similar to those of its parent native monoclonal antibody , but also possessed streptavidin - binding activity . this discovery obviates the need for chemical biotinylation of antibodies and the risk associated with antibody denaturation and provides a stable and reproducible reagent for rapid and efficient immunoassay of vee .