Unraveling the antiviral potential of multiprotein bridging factor 2 in silkworm immunity

The silk industry is facing serious threats from various pathogens, with Bombyx mori Nucleopolyhedrovirus (BmNPV) and Cytoplasmic polyhedrosis virus (BmCPV) causing considerable annual losses. Unfortunately, conventional control measures are insufficient to deal with the problem of viral diseases. Hence, substitute control strategies are immediately needed, and to achieve that, a deeper understanding of the immune mechanisms of the silkworm against viral pathogenesis is crucial. The current study focuses on evaluating the antiviral potential of BmMBF2 in limiting BmNPV and BmCPV infections. The tissue expression profile of silkworms revealed that BmMBF2 was predominantly expressed in the midgut, and infections with BmNPV/BmCPV resulted in the upregulation of this gene. RNAi-mediated downregulation of BmMBF2 significantly promoted the proliferation of the viruses, while overexpression of BmMBF2 significantly suppressed the replication of BmNPV and BmCPV. Additionally, the 20-hydroxyecdysone (20E) treatment leads to the upregulation of the BmMBF2 and a reduction in virus proliferation. Furthermore, the expression of the BmMBF2 gene through recombinant baculovirus system inhibited viral replication and reduced the DNA load of BmNPV in the silkworms. These results provide valuable insights into the antiviral potential of BmMBF2 in the silkworm, which could aid in the development of novel approaches to counter viral infections.