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Establishment of persistent infection in mouse cells by Sindbis virus and its temperature-sensitive mutants
Abstract:
The ability of wild-type (wt) Sindbis virus and six temperature-sensitive (ts) mutants to establish persistent infection in mouse L cells and a line of mouse embryo (ME) cells was determined. The wt established persistent infection in both ME cells and L cells at 39 degrees C. At 30 degrees C the wt established persistent infection in L cells but not ME cells, which did not recover from the initial infection. For the ts mutants, both cell lines survived the initial infection at 39 degrees C (the restrictive temperature) but the virus was eventually eliminated. At 30 degrees C (the permissive temperature) in L cells all mutants established persistent infection. In ME cells at 30 degrees C, RNA- mutants (unable to synthesize virus-specified RNA at 39 degrees C) established persistent infection whereas the cells did not recover from infection with RNA+ mutants (able to synthesize virus-specified RNA at 39 degrees C). The wt virus was less cytopathic in L cells than in BHK or ME cells. Interferon was produced by both L and ME cells at 30 degrees C and 39 degrees C, but its activity could not be detected in either cell line at 30 degrees C. It is proposed that establishment of persistent infection is dependent on reduced cytopathogenicity in the early stage of infection, and that further evolution of the virus then occurs to a less cytopathic form. Elimination of the virus at 39 degrees C is probably due to the action of interferon.
Insights
Wild-type Sindbis virus establishes persistent infections in mouse cells, with temperature and cell type influencing outcomes. Mutant viruses show varied persistence, suggesting reduced early cytopathogenicity is key for establishing long-term infections.
Area of Science:
- Virology
- Cell Biology
- Immunology
Background:
- Sindbis virus can cause persistent infections in mammalian cells.
- Temperature-sensitive mutants offer insights into viral replication and host-pathogen interactions.
- Cellular responses, including interferon production, play a role in viral clearance.
Purpose of the Study:
- To determine the ability of wild-type (wt) Sindbis virus and its temperature-sensitive (ts) mutants to establish persistent infections in mouse L cells and mouse embryo (ME) cells.
- To investigate the influence of temperature and viral genetic makeup on persistent infection establishment and viral elimination.
- To explore the role of cytopathogenicity and interferon in Sindbis virus persistence.
Main Methods:
- Infection of mouse L cells and ME cells with wt Sindbis virus and six ts mutants at permissive (30°C) and restrictive (39°C) temperatures.
- Monitoring of cell survival and viral elimination/persistence.
- Assessment of viral RNA synthesis capabilities (RNA- vs. RNA+ mutants).
- Detection of interferon production and activity.
Main Results:
- Wt Sindbis virus established persistent infections in both cell types at 39°C, and in L cells but not ME cells at 30°C.
- At 39°C, ts mutants were eliminated, while at 30°C, all mutants persisted in L cells.
- In ME cells at 30°C, RNA- mutants persisted, but RNA+ mutants did not.
- Wt virus exhibited lower cytopathogenicity in L cells compared to ME or BHK cells.
- Interferon was produced but not detected as active at 30°C in either cell line.
Conclusions:
- Persistent Sindbis virus infection establishment depends on reduced early-stage cytopathogenicity.
- Further viral evolution towards a less cytopathic form may facilitate persistence.
- Virus elimination at higher temperatures is likely mediated by interferon activity.