Developing Pébrine-Resistant silkworms through targeting the transmembrane protein NbTMP1 in Nosema bombycis

Pébrine disease, caused by the microsporidium Nosema bombycis, represents a significant challenge to the sericulture industry. To enhance the resistance of silkworm, we developed a transgenic strain (designated N-F12) expressing a single-chain fragment variable antibody F12 (scFvF12), targeting the critical transmembrane protein NbTMP1 of N. bombycis. The antibody was fused with the ubiquitination tag, the F-box domain at the N-terminal of Slmb protein (NSlmb), facilitating the degradation of NbTMP1 via the host's ubiquitin-proteasome system (UPS). Western blot analysis confirmed that the recombinant NSlmb::scFvF12 antibody can specifically recognize and label NbTMP1, leading to its degradation. Additionally, the proliferation of N. bombycis was significantly suppressed in N-F12 transgenic cells. Transgenic silkworms expressing N-F12 exhibited obvious resistance to N. bombycis, achieving higher survival rates without compromising key economic traits. This study demonstrates a novel strategy for pathogen resistance by utilizing the host's UPS to degrade pathogen proteins, with potential applications in sericulture and broader host-pathogen systems.