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Differential susceptibilities to BmNPV infection of two cell lines derived from the same silkworm ovarian tissues
Jun Zhang1, Xue-Mei Chen2, Chun-Dong Zhang3
1State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China; Institute of Life Sciences, Chongqing Medical University, Chongqing, China.
Abstract:
We previously established and characterized two insect cell lines (BmN-SWU1 and BmN-SWU2) from Bombyx mori ovaries. Here, we examined their differential susceptibilities to Bombyx mori nucleopolyhedrovirus (BmNPV) despite having originated from the same tissue source. BmN-SWU1 cells were susceptible and supported high titers of BmNPV replication, while BmN-SWU2 cells were resistant to BmNPV infection. Subcellular localization analysis demonstrated that very few BmNPV particles could be imported into BmN-SWU2 cells. However, initiation of BmNPV DNA replication but not amplification was detected in BmN-SWU2 cells after transfection with vA4prm-VP39-EGFP bacmid DNA. BmNPV transcription assays showed that late and very late but not early viral genes apparently were blocked in BmNSWU2 cells by unknown mechanisms. Further syncytium formation assays demonstrated that the BmNPV envelope fusion protein GP64 could not mediate BmN-SWU2 host cell-cell membrane fusion. Taken together, these results indicate that these two cell lines represent optimal tools for investigating host-virus interactions and insect antiviral mechanisms.
Insights
Two Bombyx mori cell lines show differential susceptibility to Bombyx mori nucleopolyhedrovirus (BmNPV). BmN-SWU1 cells are susceptible, while BmN-SWU2 cells are resistant, offering tools for studying insect antiviral defenses.
Area of Science:
- Insect cell line development
- Virology
- Molecular biology
Background:
- Two insect cell lines, BmN-SWU1 and BmN-SWU2, were previously established from Bombyx mori ovaries.
- Understanding differential virus susceptibility in cell lines is crucial for studying host-pathogen interactions.
Purpose of the Study:
- To investigate the differential susceptibility of BmN-SWU1 and BmN-SWU2 cell lines to Bombyx mori nucleopolyhedrovirus (BmNPV).
- To elucidate the mechanisms underlying BmNPV resistance in BmN-SWU2 cells.
Main Methods:
- Comparative analysis of BmNPV infection and replication in BmN-SWU1 and BmN-SWU2 cells.
- Subcellular localization studies of BmNPV particles.
- Viral DNA replication and transcription assays.
- Syncytium formation assays to assess viral fusion protein activity.
Main Results:
- BmN-SWU1 cells supported high titers of BmNPV replication, while BmN-SWU2 cells exhibited resistance.
- Limited BmNPV particle import and blocked late/very late gene transcription were observed in BmN-SWU2 cells.
- BmNPV DNA replication initiation occurred in BmN-SWU2 cells, but amplification was not detected.
- The BmNPV envelope fusion protein GP64 could not mediate membrane fusion in BmN-SWU2 cells.
Conclusions:
- BmN-SWU1 and BmN-SWU2 cell lines display distinct responses to BmNPV infection.
- BmN-SWU2 cells possess intrinsic antiviral mechanisms hindering BmNPV replication at multiple stages.
- These cell lines are valuable tools for dissecting insect antiviral responses and host-virus interactions.
