Abstract: 【Objective】To investigate the inhibitory effects of the different corresponding dsRNAs of gene gp64 on the replication and multiplication of Bombyx mori nuclear polyhedrosis virus(BmNPV).【Method】DsRNA are synthesized in vitro .Using the methods of measuring virus titer and real-time fluorescent quantitative RT-PCR, we test the interference effect of the different target domain, or length of gp64 gene.【Result】The maximum inhibitory effect of the three dsRNAs fragments (about 400bp) show no obvious difference (the maximum distinction of virus titer TCID50 is about 3.50).The inhibitory effect of dsRNA with about 100bp length is equal to those of with about 400bp length. At different period of RNA interference, the expression level of gp64 mRNA are downregulated (P<0.01). At 48 hpt, the expression amount of gp64 mRNA is about 1/300 of the control .【Conclusion】The six dsRNAs studied can inhibit the expression of viral gene and the multiplication of BmNPV. The best target site of RNAi is located at 1390~1499 in gp64 ORF.

Key words: dsRNA, Bombyx mori nuclear polyhedrosis virus(BmNPV), gp64 gene, viral titer, Real-time quantitative RT-PCR