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Temperature-sensitive mutants of measles virus produced from persistently infected HeLa cells
Abstract:
A persistent infection with the Edmonston strain of measles virus was established in HeLa cells in the absence of measles virus antibody (HeLaPI cells). By hemadsorption or immunofluoresnce virtually 100 per cent of the cells possessed measles virus components. HeLaPI cells produced no interferon and were not resistant to superinfection with Newcastle disease virus. HeLaPI cells contained both smooth (15--18 nm) and rought (20--35 nm) nucleocapsids as detected by electron microscopy. The virus produced from the HeLaPI cells (MVPI) varied in titer between 1.5 X 10(2) and 5.5 X10(4) PFU/ml, had a smaller plque size and was more heat resistant than wild-type measles virus. MVPI was also found to be temperature-sensitive. The temperature-sensitivity of MVPI was determined by the efficiency of plaquing at 33 degrees and 39 degrees C in Vero cell monolayers. When HeLaPI cells were incubated at 33 degrees C, there was a 50-fold increase in virus production as well as a slight increase in the percentage of cells forming infectious centers compared to HeLaPI cells grown at 37 degrees C. MVPI readily established a persistent infection in HeLa cells which also rleased temperature-sensitive virus.
Insights
This study establishes a persistent measles virus infection in HeLa cells, creating a novel cell line (HeLaPI) that produces temperature-sensitive measles virus (MVPI). This MVPI exhibits unique characteristics, including increased heat resistance and altered plaque formation, offering new avenues for measles virus research.
Area of Science:
- Virology
- Cell Biology
- Immunology
Background:
- Persistent viral infections are crucial for understanding viral pathogenesis and developing antiviral strategies.
- Measles virus (Edmonston strain) typically establishes acute infections, making persistent models valuable for study.
Purpose of the Study:
- To establish and characterize a persistent measles virus infection in HeLa cells.
- To investigate the properties of the measles virus produced from this persistent infection.
Main Methods:
- Establishing persistent infection in HeLa cells without antibody.
- Hemadsorption and immunofluorescence assays to confirm viral presence.
- Electron microscopy to analyze viral nucleocapsids.
- Plaque assays and temperature-sensitivity testing in Vero cells.
Main Results:
- HeLaPI cells showed near-complete infection with measles virus components and produced no interferon.
- Electron microscopy revealed both smooth and rough nucleocapsids in HeLaPI cells.
- The produced measles virus (MVPI) was temperature-sensitive, heat-resistant, and had smaller plaque sizes compared to wild-type measles virus.
- Incubation at 33°C increased MVPI production and infectious center formation in HeLaPI cells.
Conclusions:
- A stable persistent measles virus infection was established in HeLa cells (HeLaPI).
- The resulting measles virus (MVPI) exhibits distinct temperature-sensitive and physical properties.
- HeLaPI cells and MVPI provide a valuable model for studying measles virus persistence and temperature sensitivity.