Functional analysis of Dicer-2 gene in Bombyx mori resistance to BmNPV virus

Area of Science:

• Molecular Biology
• Entomology
• Virology
• Immunology

Background:

• Bombyx mori nucleopolyhedrovirus (BmNPV) is a significant pathogen affecting silkworm production.
• The molecular mechanisms underlying silkworm antiviral defense, particularly RNA interference (RNAi), require further elucidation.
• RNA interference is a conserved cellular defense mechanism involving the processing of double-stranded RNA (dsRNA) into small interfering RNAs (siRNAs) that target viral RNA.

Purpose of the Study:

• To identify and characterize the Dicer-2 (Dcr2) gene in Bombyx mori.
• To investigate the role of the B. mori Dcr2 gene in antiviral defense against BmNPV infection.

Main Methods:

• Identification and expression analysis of the Dicer-2 (Dcr2) gene in Bombyx mori.
• Quantitative analysis of Dcr2 mRNA expression in different tissues and developmental stages.
• Assessment of Dcr2 expression levels following BmNPV infection and dsRNA injection.
• RNA interference-mediated knockdown of Dcr2 expression to evaluate its impact on viral replication.

Main Results:

• The Dicer-2 (Dcr2) gene was identified in Bombyx mori, with highest mRNA expression observed in hemocytes.
• Dcr2 mRNA expression significantly increased in the midgut and hemocytes after BmNPV infection.
• Injection of dsRNA targeting a viral gene (dsBmSPH-1) upregulated Dcr2 expression.
• Knockdown of Dcr2 expression using specific dsRNA led to a modest increase in viral genomic DNA production, indicating enhanced viral replication.

Conclusions:

• The Dicer-2 (Dcr2) gene plays a significant role in the Bombyx mori antiviral defense pathway against BmNPV.
• Dcr2 is involved in the RNA interference-mediated response to viral infection in silkworms.
• These findings contribute to understanding silkworm immunity and developing strategies for BmNPV control.