Transcriptome profiling reveals infection strategy of an insect maculavirus

Area of Science:

• Virology
• Molecular Biology
• Insect Pathology

Background:

• Bombyx mori macula-like virus (BmMLV) is an unclassified insect RNA virus related to plant maculaviruses.
• BmMLV establishes persistent, non-lethal infections in silkworm cells, but its replication and persistence mechanisms are unknown.
• A unique BmMLV protein, p15, is highly expressed in infected cells.

Purpose of the Study:

• To investigate the role of BmMLV p15 protein in viral infection.
• To elucidate the small RNA-mediated pathways involved in maintaining BmMLV levels and persistent infections.
• To understand how this plant virus-like insect virus establishes long-term infections in insect cells.

Main Methods:

• Analysis of p15 protein expression in BmMLV-infected silkworm cells.
• Knockdown experiments targeting RNA interference (RNAi) and piRNA pathways.
• Quantification of virus-derived small RNAs (siRNAs and piRNAs) during infection progression.

Main Results:

• The BmMLV p15 protein is essential for establishing BmMLV infections in silkworm cells.
• Two distinct small RNA pathways, RNAi and piRNA, are activated during BmMLV infection.
• Cooperative function of RNAi and piRNA pathways is crucial for silencing BmMLV RNA and supporting normal cell growth.

Conclusions:

• BmMLV utilizes a unique p15 protein and dual small RNA pathways for persistent infection.
• The interplay between RNAi and piRNA pathways regulates viral load and host-insect cell interactions.
• This study proposes a novel mechanism for persistent infection by plant virus-like insect viruses.