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Persistent infection of BHK21/WI-2 cells with rubella virus and characterization of rubella variants
Abstract:
Persistently infected cell lines of BHK21/WI-2 cells have been established by infection with the wild type rubella virus strain M-33. These cell lines, BHK-MP1 and BHK-MP2, showed immunity-like resistance to superinfection with M-33 virus at both 34 degrees and 39.5 degrees C. They also showed intrinsic interference with the replication of Newcastle Disease Virus at 34 degrees C but not at 39.5 degrees C. They released a small number of infectious virus particles which were temperature sensitive variants, being able to form plaques at 34 degrees C, but not at 39.5 degrees C on BHK21/WI-2 and on its derivative, BSR. When BHK-MP1 cells were cultured at 34 degrees C in growth medium containing 10--20 microgram/ml of 5-bromodeoxyuridine (BudR) there was a 5- to 10-fold increase in infectious virus in the medium as compared with the untreated controls. Mitomycin C (0.5 microgram/ml) treatment for 7 hours likewise stimulated the release of virus from these cells. The enhancement of viral release by BudR was completely blocked by pretreatment with actinomycin D (5 microgram/ml) for 3 hours prior to BudR treatment. Since the variant can be induced by these prophage inducers and inhibited by actinomycin D it is suggested that the viral genome is converted to a DNA provirus which is analogous to the lysogenic state of bacteriophage.
Insights
Persistently infected cells resist superinfection and release temperature-sensitive rubella virus variants. Viral release is enhanced by 5-bromodeoxyuridine (BudR) and mitomycin C, suggesting a provirus state.
Area of Science:
- Virology
- Cell Biology
- Molecular Biology
Background:
- Persistent viral infections can alter host cell behavior and viral replication dynamics.
- Understanding viral interference mechanisms is crucial for developing antiviral strategies.
- Rubella virus (M-33 strain) infection can establish persistent cell lines.
Purpose of the Study:
- To establish and characterize persistently infected BHK21/WI-2 cell lines with rubella virus.
- To investigate the resistance of these cell lines to superinfection and interference with other viruses.
- To explore the induction of viral release using specific chemical agents.
Main Methods:
- Establishment of persistently infected BHK21/WI-2 cell lines (BHK-MP1, BHK-MP2) with rubella virus M-33.
- Superinfection assays with rubella virus and Newcastle Disease Virus at different temperatures.
- Treatment of infected cells with 5-bromodeoxyuridine (BudR), mitomycin C, and actinomycin D to assess viral release.
- Characterization of released viral particles for temperature sensitivity.
Main Results:
- Persistently infected cell lines (BHK-MP1, BHK-MP2) exhibited resistance to rubella virus superinfection.
- These cell lines showed interference with Newcastle Disease Virus replication, dependent on temperature.
- Infectious, temperature-sensitive rubella virus variants were released.
- Viral release was significantly enhanced by 5-bromodeoxyuridine (BudR) and mitomycin C.
- BudR-induced viral release was inhibited by actinomycin D.
Conclusions:
- Persistently infected cells demonstrate altered responses to viral challenge and replication.
- The induction of viral release by agents like BudR and mitomycin C suggests a provirus state analogous to bacteriophage lysogeny.
- The findings provide insights into rubella virus persistence and potential mechanisms for viral genome integration.