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Recovery of a Sendai virus variant with temperature-sensitive hemolytic activity from persistently infected cells
Abstract:
A persistently infected cell line designated MB/Senas was established by cultivation of mouse brain cells from four-day-old C3H mice infected intracerebrally at birth with 10(6) PFU of Sendai virus, strain 52. After 5 passages, 0.16 per cent of Sendai52 antiserum (containing two 50 per cent plaque reducing doses/ml of serum) was introduced into the culture medium. The addition of antiserum was accompanied by a rise in cell-associated viral antigen from a level of 5 per cent antigen positive cells to 100 per cent demonstrable by both intracellular and membrane immunofluorescence. A variant of Sendai52 virus, designated Sendaias, was recovered from MB/Senas by inoculation of supernatant medium into chick embryos. Infection of chick embryos at 37 degrees C was abortive. Fifty per cent or less of chick embryos infected at dilutions 10(-1) to 10(-9) yielded detectable virus. Hemagglutination (HA) was weak but could be improved by trypsinization of allantoic fluids. Neuraminidase (NA) activity was barely detectable. Hemolysis (HE) was absent. Propagation of Sendaias virus at 33 degrees C showed no change from weak HA and NA activities but HE activity was now apparent which was temperature sensitive. Mortality of infected chick embryos increased to 100 per cent. HE activity and lethality for chick embryos was thermolabile at 45 degrees C.
Insights
Researchers established a persistently infected cell line using Sendai virus (strain 52) in mouse brain cells. Addition of antiserum induced a variant, Sendaias, with temperature-sensitive hemolysis and increased chick embryo lethality.
Area of Science:
- Virology
- Cell Biology
- Immunology
Background:
- Persistent viral infections can alter viral properties.
- Sendai virus is a paramyxovirus known to cause respiratory and neurological disease.
- Studying viral variants can reveal insights into viral pathogenesis and host-virus interactions.
Purpose of the Study:
- To establish a persistently infected cell line with Sendai virus.
- To characterize a variant virus recovered from this cell line.
- To investigate the properties of the variant virus, including its hemagglutination, neuraminidase, hemolysis activity, and pathogenicity.
Main Methods:
- Establishment of a persistently infected mouse brain cell line (MB/Senas) with Sendai virus (strain 52).
- Introduction of Sendai virus antiserum to induce viral variant selection.
- Recovery and characterization of the variant virus (Sendaias) in chick embryos.
- Assays for hemagglutination (HA), neuraminidase (NA), and hemolysis (HE) activity.
- Determination of temperature sensitivity and chick embryo lethality.
Main Results:
- A persistently infected cell line (MB/Senas) was established, showing 100% cell-associated viral antigen after antiserum addition.
- A variant virus, Sendaias, was recovered and showed weak HA and NA activity, absent HE activity at 37°C.
- Propagation at 33°C revealed temperature-sensitive HE activity and 100% chick embryo mortality.
- HE activity and lethality were thermolabile at 45°C.
Conclusions:
- Persistent infection with Sendai virus can lead to the emergence of variants with altered biological properties.
- The Sendaias variant exhibits temperature-sensitive hemolysis and increased pathogenicity for chick embryos.
- These findings highlight the adaptability of Sendai virus and the potential for altered virulence in persistently infected hosts.