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Persistent baculovirus infection results from deletion of the apoptotic suppressor gene p35
1Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 115, Taiwan, Republic of China.
Abstract:
Infection with the wild-type baculovirus Autographa californica multiple nuclear polyhedrosis virus (AcMNPV) results in complete death of Spodoptera frugiperda (Sf) cells. However, infection of Sf cells with AcMNPV carrying a mutation or deletion of the apoptotic suppressor gene p35 allowed the cloning of surviving Sf cells that harbored persistent viral genomes. Persistent infection established with the virus with p35 mutated or deleted was blocked by stable transfection of p35 in the host genome or by insertion of the inhibitor of apoptosis (iap) gene into the viral genome. These artificially established persistently virus-infected cells became resistant to subsequent viral challenge, and some of the cell lines carried large quantities of viral DNA capable of early gene expression. Continuous release of viral progenies was evident in some of the persistently virus-infected cells, and transfection of p35 further stimulated viral activation of the persistent cells, including the reactivation of viruses in those cell lines without original continuous virus release. These results have demonstrated the successful establishment of persistent baculovirus infections under laboratory conditions and that their establishment may provide a novel continuous, nonlytic baculovirus expression system in the future.
Insights
Scientists created persistent baculovirus infections in Spodoptera frugiperda cells by mutating the p35 gene. These cells resist viral challenges, offering a potential new expression system.
Area of Science:
- * Virology
- * Molecular Biology
- * Cell Biology
Background:
- * Wild-type Autographa californica multiple nuclear polyhedrosis virus (AcMNPV) causes lethal infections in Spodoptera frugiperda (Sf) cells.
- * Viral apoptotic suppressor genes, like p35, are crucial for lytic infection cycles.
Purpose of the Study:
- * To establish and characterize persistent baculovirus infections in Sf cells.
- * To investigate the role of the p35 gene in viral persistence.
- * To explore the potential of persistently infected cells as a novel expression system.
Main Methods:
- * Infection of Sf cells with AcMNPV mutated or deleted for the p35 gene.
- * Cloning of surviving Sf cells harboring persistent viral genomes.
- * Stable transfection of p35 into host cells or insertion of the inhibitor of apoptosis (iap) gene into the viral genome to block persistence.
- * Assessment of resistance to subsequent viral challenge and viral DNA/progeny production.
Main Results:
- * AcMNPV with mutated or deleted p35 allowed the establishment of persistent infections in Sf cells.
- * Stable expression of p35 or viral iap genes blocked the establishment of persistent infections.
- * Persistently infected cells exhibited resistance to superinfection and some showed continuous viral progeny release.
- * Transfection of p35 reactivated viral gene expression and progeny release in non-releasing persistent cell lines.
Conclusions:
- * Persistent baculovirus infections can be successfully established in Sf cells under laboratory conditions.
- * The p35 gene plays a critical role in preventing baculovirus persistence.
- * Artificially established persistent baculovirus infections represent a promising novel system for continuous, nonlytic viral expression.