| Summary: | <p>Abstract</p> <p>Background</p> <p>Noroviruses cause epidemic outbreaks of gastrointestinal illness in all age-groups. The rapid onset and ease of person-to-person transmission suggest that inhibitors of the initial steps of virus binding to susceptible cells have value in limiting spread and outbreak persistence. We previously generated a monoclonal antibody (mAb) 54.6 that blocks binding of recombinant norovirus-like particles (VLP) to Caco-2 intestinal cells and inhibits VLP-mediated hemagglutination. In this study, we engineered the antigen binding domains of mAb 54.6 into a single chain variable fragment (scFv) and tested whether these scFv could function as cell binding inhibitors, similar to the parent mAb.</p> <p>Results</p> <p>The scFv<sub>54.6 </sub>construct was engineered to encode the light (V<sub>L</sub>) and heavy (V<sub>H</sub>) variable domains of mAb 54.6 separated by a flexible peptide linker, and this recombinant protein was expressed in <it>Pichia pastoris</it>. Purified scFv<sub>54.6 </sub>recognized native VLPs by immunoblot, inhibited VLP-mediated hemagglutination, and blocked VLP binding to H carbohydrate antigen expressed on the surface of a CHO cell line stably transfected to express α 1,2-fucosyltransferase.</p> <p>Conclusion</p> <p>scFv<sub>54.6 </sub>retained the functional properties of the parent mAb with respect to inhibiting norovirus particle interactions with cells. With further engineering into a form deliverable to the gut mucosa, norovirus neutralizing antibodies represent a prophylactic strategy that would be valuable in outbreak settings.</p>
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