Endogenous RNA virus-derived elements exhibit functional divergence in modulating development and virus susceptibility in Bombyx mori.

Endogenous RNA virus-derived elements in Bombyx mori exhibit distinct roles in development and virus susceptibility, with BmChuEVE3 and BmToEVE showing contrasting effects.

• Why it matters: Understanding how viral elements influence host biology can reveal mechanisms of development and antiviral defense, addressing gaps in Lepidoptera functional genomics.
• What they did: Seven transcriptionally active nrEVEs from four RNA virus families were identified and analyzed through small-RNA profiling, functional knockdowns, yeast two-hybrid screening, and transcriptomics.
• The result: Depleting BmChuEVE3 increased susceptibility to BmNPV and BmCPV, while BmToEVE silencing reduced BmNPV levels and boosted immune responses, demonstrating functional diversification in virus-host interactions.