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Virus and host cell-dependent variation in transcription of the mumps virus genome
M A Afzal1, G D Elliott, B K Rima
1Northern Ireland Centre for Genetic Engineering, Queen's University of Belfast.
Abstract:
Evidence has been presented that generation of polycistronic readthrough RNAs in mumps virus-infected cells is not a simple stochastic process with strain-dependent variations in the generation of certain readthrough products, but that this process is affected by host as well as viral factors. RNAs extracted from infected Vero cells or chicken embryo fibroblast (CEF) cells have been analysed by Northern blotting with virus-specific probes for the nucleocapsid (N), phosphoprotein (P), matrix (M), fusion (F), small hydrophobic (SH) and haemagglutinin-neuraminidase (HN) genes. Vero cells infected with tissue culture cell-adapted virus strains generate monocistronic as well as polycistronic RNAs. Transcription analysis of Vero cells infected with an egg-adapted strain reveal the absence of monocistronic M and F transcripts, with a concomitant increase in readthrough transcripts involving these genes. When the same virus infects CEF cells monocistronic RNAs accumulate. The presence of viral proteins in the various virus/host cell combinations assessed by immunofluorescence with mumps virus-specific monoclonal antibodies for the N, P, M, F and HN proteins correlates well with the patterns of transcription.
Insights
Mumps virus RNA transcription is influenced by both host and viral factors, not just random chance. Different cell types and virus strains alter the production of viral transcripts.
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Mumps virus gene expression involves transcription of monocistronic and polycistronic RNAs.
- The generation of polycistronic readthrough RNAs is a key aspect of paramyxovirus replication.
Purpose of the Study:
- To investigate the factors influencing polycistronic readthrough RNA generation in mumps virus infections.
- To determine the role of host cell type and viral strain in mumps virus transcription patterns.
Main Methods:
- Northern blotting analysis of viral RNAs extracted from infected Vero cells and chicken embryo fibroblast (CEF) cells.
- Analysis of viral protein expression using immunofluorescence with virus-specific monoclonal antibodies.
Main Results:
- Vero cells infected with adapted strains produced both monocistronic and polycistronic RNAs.
- An egg-adapted strain in Vero cells showed reduced monocistronic M and F transcripts, with increased readthrough transcripts.
- In CEF cells, the same virus strain led to the accumulation of monocistronic RNAs.
- Viral protein expression patterns correlated with observed transcription profiles across different host cells and virus strains.
Conclusions:
- Polycistronic readthrough RNA generation in mumps virus is a regulated process influenced by host-specific factors and viral strain adaptations.
- Host cell environment and viral adaptation significantly impact mumps virus transcription, affecting gene expression and protein synthesis.