DUOX-Generated Intestinal ROS Restrict Spore Adhesion and Invasion of Nosema bombycis in Silkworm Bombyx mori

The intestinal immune system is essential for insects to defend against pathogenic infections, while the dual oxidase-reactive oxygen species (DUOX-ROS) pathway is a key component. However, the role of the DUOX-ROS pathway in Bombyx mori against Nosema bombycis, a significant pathogen of this species, remains poorly characterized. In this study, four core components of the DUOX-ROS pathway in B. mori (BmGαq, BmPLCβ1, BmPLCβ4, and BmDUOX) were identified using bioinformatics. Pathogen induction experiments showed significant upregulation of BmDUOX and increased ROS production following N. bombycis infection. Immunofluorescence and antibody-blocking assays demonstrated that BmDUOX localizes to the plasma membrane and is essential for inhibiting spore adhesion and invasion. This study provides the first systematic evidence of DUOX-ROS-mediated anti-microsporidian immunity in B. mori, which may provide a theoretical basis for the future development of ROS-based disease control strategies in sericulture.