Endogenous RNA virus–derived elements exhibit functional divergence in modulating development and virus susceptibility in <i>Bombyx mori</i>

Yeast two-hybrid screening and transcriptomic analyses further implicated both nrEVEs with cuticle-associated and reproductive processes. Importantly, BmChuEVE3 knockdown broadly suppressed metabolic and immune responses, accompanied by increased <i>B.mori nucleopolyhedrovirus</i> (BmNPV) and <i>cypovirus</i> (BmCPV). By contrast, BmToEVE silencing markedly reduced BmNPV accumulation and enhanced host defense-related transcriptional responses.

Its effect on BmCPV was comparatively modest and emerged only at the later infection stage. Overall, our findings reveal functional diversification of silkworm nrEVEs and highlight the contribution of virus-derived sequences to developmental regulation and antiviral physiology in a lepidopteran host.</p>