Functional analysis of BmTsp.C in modulating infection of BmNPV through apoptosis pathways in domestic silkworm (Bombyx mori).

The silkworm, Bombyx mori, is a crucial model insect in agriculture and biological research. Tetraspanins, known for their effects in regulating cellular functions like cell signalling, adhesion, migration and diffusion, take on a crucial role in viral dynamics, influencing both viral spread and entry into host cells. In this study, a tetraspanin gene called BmTsp.C from the silkworm genome was identified and investigated. Tissue profiles showed that BmTsp.C has the highest transcription level in midgut, with a marked increase following viral infection. The immunofluorescence localization suggested that BmTsp.C is primarily distributed on the cell membrane. Additionally, overexpression of BmTsp.C in BmN cells facilitated the proliferation of BmNPV. Meanwhile, siRNA-mediated knockdown of BmTsp.C could inhibit viral proliferation. In addition, knockdown of BmTsp.C at the individual level further validated the remarkable effect of BmTsp.C during viral infestation. Furthermore, overexpression of BmTsp.C could regulate the expression of apoptosis-related genes. Results from flow cytometry indicated a decrease in the number of apoptotic cells after overexpression of BmTsp.C. Taken together, our results demonstrated that BmTsp.C, as an important factor in the Tetraspanin-enriched microdomains, exerts a significant influence on the proliferation of BmNPV, most likely through the cellular apoptosis pathway.