The original antibody was generated by immunizing female white leghorn chickens with 50 µg of recombinant B7-H4 protein (Phe29 to Ala258) through intramuscular injection. The spleens of the chickens were harvested 7 days after the final immunization to construct an scFv antibody library. The antibody was isolated by panning against B7-H4 protein.