几十年来，猫传染性疾病一直是最常见的健康问题和导致猫死亡的主要原因之一。这些疾病包括弓形虫病、猫白血病病毒（FeLV）和尤其是猫免疫缺陷病毒（FIV）疾病。早期诊断对增加治疗成功的机会至关重要。通常，测量IgG水平被认为是指示某个病原体的个体免疫状态的指标。与猫IgG特异性的抗体是检测试剂的关键组分。在本研究中，采用噬菌体展示技术选择了与猫IgG结合的单链抗体（scFv）。对纯化的猫IgG进行了三轮生物富集筛选。通过间接酶联免疫吸附试验（ELISA），选择了两个具有最佳与猫IgG结合能力的scFv克隆进行生化特性分析。此外，表达和纯化了选定的scFv（N14）在细菌系统中。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳显示纯化的N14的大小为29 kDa。采用夹心ELISA评估纯化的scFv与猫IgG的结合能力。如预期，纯化的N14具有与猫IgG结合的能力。此外，通过修饰N14，创建了一个含有碱性磷酸酶（AP）的scFv-AP融合平台。表面等离子共振（SPR）结果显示，N14-AP与猫IgG的亲和结合值为0.3 ± 0.496 μM。此外，直接ELISA表明N14-AP对细胞裂解物和纯化蛋白中的猫IgG具有结合能力。此外，N14-AP可应用于基于电感应的猫IgG检测，检测限为10.42 nM。总之，本研究成功选择了与猫IgG结合的scFv，并开发了一个可进一步改良并应用于猫传染性疾病检测试剂盒的scFv-AP平台。© 2023 The Authors. Published by American Chemical Society.

For many decades, feline infectious disease has been among the most common health problems and a leading cause of death in cats. These diseases include toxoplasmosis, feline leukemia virus (FeLV), and particularly feline immunodeficiency virus (FIV) disease. Early diagnosis is essential to increase the chance of successful treatment. Generally, measurement of the IgG level is considered to be indicative of an individual's immune status for a particular pathogen. The antibodies specific to feline IgG are crucial components for the development of a detection kit. In this study, feline IgG-bound scFv was selected using phage display technology. Three rounds of biopanning were conducted against purified feline IgG. Through an indirect enzyme-linked immunosorbent assay (ELISA), two scFv clones demonstrating the best binding ability to feline IgG were chosen for biochemical characterization. In addition, the selected scFv (N14) was expressed and purified in a bacterial system. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the size of the purified N14 was 29 kDa. A sandwich ELISA was used to evaluate the binding capacity of the purified scFv to feline IgG. As expected, the purified N14 had the capacity to bind feline IgG. Furthermore, N14 was modified to create a scFv-alkaline phosphatase (scFv-AP) fusion platform. The surface plasmon resonance (SPR) results revealed that N14-AP bound to feline IgG with an affinity binding value of 0.3 ± 0.496 μM. Additionally, the direct ELISA demonstrated the binding capacity of N14-AP to feline IgG in both cell lysate and purified protein. Moreover, N14-AP could be applied to detect feline IgG based on electrosensing with a detection limit of 10.42 nM. Overall, this study successfully selected a feline IgG-bound scFv and developed a scFv-AP platform that could be further engineered and applied in a feline infectious disease detection kit.© 2023 The Authors. Published by American Chemical Society.