Downregulation of BmSTAT transcription factor promoted nucleopolyhedrovirus replication in Bombyx mori

The Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway plays a crucial role in the viral immune processes of organisms, with STAT being a key transcription factor downstream in this pathway. The <i>STAT</i> gene of <i>Bombyx mori</i> has two splicing forms, named <i>BmSTAT-S</i> and <i>BmSTAT-L</i>. This study compared the effects of the two splicing forms on <i>Bombyx mori</i> nucleopolyhedrovirus (BmNPV) infection through cell-level interference and further explored whether <i>BmSTAT</i> participates in the immune response to BmNPV infection via transgenic intervention at the individual level. Our research results indicated that BmNPV upregulates the expression of <i>BmSTAT-S</i> and <i>BmSTAT-L</i> in <i>Bombyx mori</i> BmE cells and larvae. Furthermore, BmE cells with interference of <i>BmSTAT-S</i> or <i>BmSTAT-L</i> displayed significantly higher expression levels of the viral gene <i>GP41</i> and increased viral fluorescence compared to the control group after 48 h of infection with BmNPV. Then, we constructed transgenic silkworms with genetic interference, and the results showed that both the transgenic silkworms with systemic interference and midgut-specific interference of the two splice forms of <i>BmSTAT</i> exhibited significantly reduced survival rates and increased viral replication numbers after infection with BmNPV. The above results indicated that the <i>BmSTAT</i> gene is involved in the immune response of <i>Bombyx mori</i> to BmNPV and these findings lay the foundation for further research on the mechanism of JAK/STAT signaling pathway involvement in BmNPV infection.