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Bombyx mori nucleopolyhedrovirus FP25K is essential for maintaining a steady-state level of v-cath expression

Susumu Katsuma1, Tadashi Nakanishi, Toru Shimada

  • 1Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan. katsuma@ss.ab.a.u-tokyo.ac.jp

Virus Research
|December 23, 2008
PubMed

Insights

Bombyx mori nucleopolyhedrovirus FP25K regulates viral cathepsin (v-cath) expression and secretion. This is crucial for efficient post-mortem host degradation in infected silkworms.

Area of Science:

  • Virology
  • Molecular Biology
  • Insect Pathology

Background:

  • The Bombyx mori nucleopolyhedrovirus (BmNPV) fp25K gene product is known to be essential for post-mortem host degradation.
  • The precise mechanism by which FP25K influences host degradation remains unelucidated.

Purpose of the Study:

  • To investigate the role of BmNPV FP25K in regulating viral cathepsin (v-cath) expression and secretion.
  • To elucidate the mechanism linking FP25K to post-mortem host degradation.

Main Methods:

  • Western blot analysis to assess V-CATH secretion and pro-V-CATH accumulation.
  • Quantitative reverse transcription PCR (qRT-PCR) to measure v-cath mRNA expression levels.
  • Comparison between wild-type BmNPV and a BmNPV mutant lacking functional fp25K (Bm25KD).

Main Results:

  • Disruption of fp25K in Bm25KD significantly attenuated V-CATH secretion and pro-V-CATH accumulation in infected BmN cells and B. mori larvae.
  • v-cath mRNA expression levels were comparable at 3 days postinfection (dpi) but markedly decreased in Bm25KD-infected cells at 4 dpi.
  • FP25K is essential for maintaining v-cath expression after 4 dpi, coinciding with V-CATH secretion.

Conclusions:

  • BmNPV FP25K plays a critical role in the transcriptional regulation of v-cath and the efficient secretion of V-CATH.
  • Sustained v-cath expression post-4 dpi, facilitated by FP25K, is necessary for effective post-mortem host degradation.

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