Abstract: 【Objective】 The purpose of this test was to screen the single chain antibody fragment (scFv) against the non-structural protein NS1 of Porcine parvovirus (PPV), which laid a foundation for the further study of PPV. 【Method】 The expression of PPV NS1 protein was induced by prokaryotic expression system and purified,and the recombinant NS1 protein was used for animal immunization，and serum titer level was detected.Total RNA was extracted from mouse spleen and reverse-transcribed into cDNA,which was used as template to amplify the sequences of variable domain of heavy chains (VH) and variable domain of light chains (VL).scFv gene was amplified by overlap PCR,and was connected to pSEXRTL2 phage vector and electrotransformed into E.coli XLⅠ-Blue competent cells.A murine scFv antibody library against PPV NS1 was constructed,and its quality and storage capacity were measured.Phage display technology was used to screen scFv specific to NS1 protein,and the affinity between the antigen and the positive phage clone was detected by ELISA and Western blotting. 【Result】 In this experiment,soluble PPV NS1 recombinant protein was successfully expressed and purified.The capacity of the murine anti-NS1 scFv library was 2.7×10⁷ CFU/mL,and the positive rate of the library was 87.5%.After four rounds of "adsorption-elution-enrichment" phage screening,two scFv strains with high affinity for PPV NS1 protein were obtained. 【Conclusion】 In this study,a murine scFv phage library against PPV NS1 protein was successfully constructed by prokaryotic expression and purification of recombinant protein NS1.scFv that could bind specifically to PPV NS1 recombinant protein was obtained by phage display technique.The results provided the basis for further research and development of anti-PPV drugs and diagnostic reagents.

Key words: Porcine parvovirus(PPV); single chain antibody fragment(scFv); NS1 protein; phage library