Application of phage display in selecting Tomato spotted wilt virus-specific single-chain antibodies (scFvs) for sensitive diagnosis in ELISA

A panel of recombinant single-chain antibodies (scFvs) against structural p roteins of Tomato spotted wilt virus (TSWV) was retrieved from a human comb inatorial scFv antibody library using the novel phage display technique. Af ter subcloning the encoding DNA sequences in the expression vector pSKAP/S, which allowed the scFvs to be expressed as alkaline phosphatase fusion pro teins, 17 different scFv antibodies were obtained. Of these, 12 scFvs were directed against the nucleoprotein (N) and 5, putatively, against the glyco proteins (G1 and G2). Five of the N-specific antibodies cross-reacted with two other tospoviruses (Tomato chlorotic spot virus and Groundnut ringspot virus), but none recognized the more distantly related tospoviruses Impatie ns necrotic spot virus, Watermelon silverleaf mottle virus, Iris yellow spo t virus, or Physalis severe mottle virus. The successful use of one of the antibodies as coating and detection reagent in a double-antibody sandwich e nzyme-linked immunosorbent assay showed the potential of the phage display system in obtaining antibodies for routine TSWV diagnosis.