Related Experiment Videos
An electron-microscopic study of the development of virulent and avirulent strains of Semliki forest virus in mouse
Abstract:
Two strains of Semliki Forest Virus (SFV), the avirulent and virulent, were used to study the development of virus in both baby and adult mouse brain. The development of SFV in the brain was similar in baby and adult brain using the virulent strain and in the baby mouse brain using the avirulent strain. Mature virus could not be found in adult mouse brain using the avirulent strain. This paper shows that extracellular virus particles near the cell membrane stimulate the formation of coated vesicles and thus absorption of virus particles by the cell. It is suggested that these coated vesicles with contained virus particles are stimulated to develop nucleoid cores on their membrane forming cytopathic vacuoles, Type II (CPV-II). Excessive membrane growth takes place and the membrane of the CPV-II with the nucleoid cores invaginates to form intravacuolar tubules. It is suggested that these tubules become responsible fro the formation of mature virus particles. Thus the membrane of the CPV-II appears to be responsible for the development of both the inner core and outer coat of the virus.
Insights
Semliki Forest Virus (SFV) develops similarly in baby and adult mouse brains with virulent strains. Mature avirulent SFV was absent in adult mouse brains, suggesting a unique developmental pathway.
Area of Science:
- Virology
- Cell Biology
- Neuroscience
Background:
- Semliki Forest Virus (SFV) infects various hosts.
- Understanding viral development in the central nervous system is crucial.
Purpose of the Study:
- To investigate the development of virulent and avirulent SFV strains in baby and adult mouse brains.
- To elucidate the cellular mechanisms of SFV replication and maturation.
Main Methods:
- Infection of baby and adult mouse brains with two SFV strains.
- Microscopic examination of viral development and cellular interactions.
Main Results:
- SFV development was similar in baby and adult mouse brains with the virulent strain.
- Avirulent SFV replicated in baby mouse brains but not maturely in adult mouse brains.
- Extracellular virus particles induced coated vesicles, leading to cytopathic vacuoles Type II (CPV-II).
- Intravacuolar tubules within CPV-II are suggested to be sites of mature virus formation.
Conclusions:
- The study details a proposed mechanism for SFV replication involving cellular membrane structures.
- CPV-II and its associated tubules are implicated in the assembly of both the viral core and outer coat.
- Differences in avirulent SFV development between young and adult mice highlight age-dependent host-pathogen interactions.