Bombyx mori nucleopolyhedrovirus BM5 protein regulates progeny virus production and viral gene expression

Area of Science:

• Virology
• Molecular Biology
• Insect Pathology

Background:

• Bombyx mori nucleopolyhedrovirus (BmNPV) is a significant pathogen affecting silkworms.
• orf5 (Bm5) is a core gene in lepidopteran baculoviruses, encoding a protein with a conserved DUF3627 domain.
• The function of Bm5 in the viral life cycle remains largely uncharacterized.

Purpose of the Study:

• To investigate the role of the Bm5 protein in BmNPV replication and pathogenesis.
• To elucidate the function of the DUF3627 domain within the BM5 protein.

Main Methods:

• Generation and characterization of Bm5 deletion mutants in B. mori.
• Quantification of viral titers and occlusion bodies (OBs) in infected cells and larvae.
• Analysis of viral gene expression using transcriptomic approaches.
• Immunocytochemical localization of the BM5 protein.

Main Results:

• Bm5 disruption significantly reduced budded virus titers and occlusion body formation.
• Viral genome replication was unaffected, but late-stage viral gene expression was aberrant.
• BM5 protein was localized to the nuclear membrane.
• The DUF3627 domain is essential for OB production, viral gene regulation, and BM5 localization.
• Bm5 mutants delayed larval mortality compared to wild-type BmNPV.

Conclusions:

• BM5 plays a critical role in progeny virus production, particularly OB assembly.
• BM5 is involved in regulating viral gene expression during the late stages of infection.
• The BM5 protein, via its DUF3627 domain, influences baculovirus pathogenesis and host-pathogen interactions.