State Key Laboratory of Animal Nutrition and Feeding, Frontiers Science Center for Molecular Design Breeding (MOE), China Agricultural University, Beijing 100193, China.
Int J Mol Sci. 2024 Mar 25;25(7):3638. doi: 10.3390/ijms25073638.
Enterotoxigenic (ETEC) strains are significant contributors to postweaning diarrhea in piglets. Of the ETEC causing diarrhea, K88 and F18 accounted for 92.7%. Despite the prevalence of ETEC K88 and F18, there is currently no effective vaccine available due to the diversity of these strains. This study presents an innovative approach by isolating chicken-derived single-chain variable fragment antibodies (scFvs) specific to K88 and F18 fimbrial antigens from chickens immunized against these ETEC virulence factors. These scFvs effectively inhibited adhesion of K88 and F18 to porcine intestinal epithelial cells (IPEC-J2), with the inhibitory effect demonstrating a dose-dependent increase. Furthermore, a bispecific scFv was designed and expressed in . This engineered construct displayed remarkable potency; at a concentration of 25.08 μg, it significantly reduced the adhesion rate of ETEC strains to IPEC-J2 cells by 72.10% and 69.11% when challenged with either K88 or F18 alone. Even in the presence of both antigens, the adhesion rate was notably decreased by 57.92%. By targeting and impeding the initial adhesion step of ETEC pathogenesis, this antibody-based intervention holds promise as a potential alternative to antibiotics, thereby mitigating the risks associated with antibiotic resistance and residual drug contamination in livestock production. Overall, this study lays the groundwork for the development of innovative treatments against ETEC infections in piglets.
肠产毒性（ETEC）菌株是导致仔猪断奶后腹泻的重要因素。在引起腹泻的 ETEC 中，K88 和 F18 占 92.7%。尽管 ETEC K88 和 F18 很普遍，但由于这些菌株的多样性，目前尚无有效的疫苗可用。本研究提出了一种创新的方法，从针对这些 ETEC 毒力因子免疫的鸡中分离出特异性针对 K88 和 F18 菌毛抗原的鸡源性单链可变片段抗体（scFv）。这些 scFv 有效抑制了 K88 和 F18 与猪肠上皮细胞（IPEC-J2）的粘附，抑制作用呈剂量依赖性增加。此外，还设计并在大肠杆菌中表达了双特异性 scFv。这种工程构建体表现出显著的效力；在浓度为 25.08μg 时，它显著降低了 ETEC 菌株与 IPEC-J2 细胞的粘附率，当单独用 K88 或 F18 挑战时，粘附率分别降低了 72.10%和 69.11%。即使存在两种抗原，粘附率也明显降低了 57.92%。通过靶向和阻碍 ETEC 发病机制的初始粘附步骤，这种基于抗体的干预措施有望成为抗生素的替代品，从而降低抗生素耐药性和牲畜生产中残留药物污染的风险。总体而言，本研究为开发针对仔猪 ETEC 感染的创新疗法奠定了基础。
