Functional characterization of a novel protein-coding circular RNA, circRNA_1193, from the <i>mAAP</i> gene in silkworm and its role in antiviral defense against BmCPV

This study identified a novel circular RNA, circRNA_1193, in the silkworm <i>Bombyx mori</i>, and revealed its critical role in antiviral defense against <i>Bombyx mori</i> cytoplasmic polyhedrosis virus (BmCPV). We demonstrated that circRNA_1193 exhibits tissue-specific expression, is upregulated in response to BmCPV infection, and possesses antiviral activity. Importantly, we show that circRNA_1193 encodes the viral protein VSP35, which is essential for its antiviral function. These findings provide new insights into the complex regulatory mechanisms of circular RNAs in antiviral immunity and underscore the potential of circular RNAs as therapeutic targets in viral diseases. The identification of a protein-coding circular RNA with antiviral activity in <i>B. mori</i> has broader implications for understanding the evolution and diversity of host defense mechanisms against viruses.