Avian influenza virus transmission is suppressed in chickens fedexpressing the 3D8 single-chain variable fragment protein.
Acta Vet Hung. 2019 Dec ;67(4):610-618. PMID: 31842597
The 3D8 single-chain variable fragment (scFv) is a mini-antibody sequence with independent nuclease activity that shows antiviral effects against all types of viruses in chickens and mice. In this study, chickens were treated daily with an oral dose of 10CFUexpressing either a secreted or anchored 3D8 scFv for three weeks. Afteradministration, the chickens were challenged with avian influenza virus (AIV). From each experimental group, three chickens were directly infected with 100µL of 10EID/mL H9N2 AIV and seven chickens were indirectly challenged through contact transmission. oropharyngeal and cloacal swab samples were collected at 3, 5, 7, and 9 days post-inoculation (dpi) from AIV-challenged chickens, AIV Shedding titres were measured by quantitative real-time PCR. Contact transmission in the chickens that were fed 3D8 scFv-secretingshowed a significant reduction in viral shedding when compared with other groups. These results suggest thatsecreting 3D8 provides a basis for the development of ingestible antiviral probiotics with activity against AIV.