Characteristics and Antiadhesion Activity of Chicken Single-Chain Fragment Variable Antibodies Against <i>Helicobacter pylori</i> Adhesin A

Helicobacter pylori adheres to gastric epithelial cells via adhesins like H. pylori adhesin A (HpaA), causing persistent colonization and inflammation. In this study, we isolated chicken single-chain fragment variable (scFv) antibodies targeting HpaA from a chicken immune scFv antibody library. Four antibodies (H2-D1, H1-B11, H2-D9, and H2-A3) were analyzed, evaluating characteristics as well as antiadhesion effects. These antibodies maintained binding activity under simulated gastrointestinal pH conditions and demonstrated high thermal stability. They exhibited specific binding and high affinity to the recombinant HpaA protein as well as HpaA proteins present in clinical H. pylori strains. Flow cytometric analysis revealed that these scFv antibodies significantly inhibited the adhesion of HpaA protein and various H. pylori strains to AGS cells. Our findings suggested that they hold potential for diagnostic and therapeutic use against H. pylori infection, providing a foundation for the development of antiadhesion reagents and antibody drugs for H. pylori infection.