# Antibody Screening and Binding Prediction Analysis Targeting Stx2

## TL;DR

Researchers identified two antibodies that target a dangerous toxin from E. coli, finding that one has stronger binding while the other shows better protection in mice.

## Contribution

The study introduces two human monoclonal antibodies against Stx2 and reveals a non-linear relationship between binding affinity and protective efficacy.

## Key findings

- YG12-2 has stronger binding energy and higher affinity based on structural modeling and experimental validation.
- YG12-1 demonstrates better protective activity in a mouse model despite lower binding affinity.
- The results highlight the importance of epitope accessibility and pharmacokinetics in neutralization outcomes.

## Abstract

Background: Shiga toxin (Stx), produced by enterohemorrhagic Escherichia coli (EHEC), is a highly potent exotoxin responsible for severe complications such as hemolytic uremic syndrome (HUS). Among its isoforms, Stx2 exhibits stronger cytotoxicity and poses greater clinical risk, yet no effective therapy currently exists. Methods: In this study, two human monoclonal antibodies, YG12-1 and YG12-2, were identified from a phage display library and systematically characterized using an integrated modeling–validation workflow. Results: Structural modeling with ImmuneBuilder and Rosetta revealed that YG12-2 possessed a longer CDRH3 topology, more short-range hydrogen bonds, and stronger electrostatic complementarity, corresponding to lower binding energy and higher apparent affinity in ELISA and SPR. Although YG12-2 had a better affinity, YG12-1 shows better protective activity in a murine model of acute peritoneal infection. This paradox highlights a non-linear relationship between structural affinity and biological efficacy, emphasizing the importance of functional epitope accessibility and pharmacokinetic behavior in determining neutralization outcomes. Conclusions: Overall, these results indicated that targeting Stx2 with YG12-1 and YG12-2 could serve as a promising protective strategy against E. coli O157:H7 infection.