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Mutations in the VP1 coding region of polyomavirus determine differentiating stage specificity
L Ricci1, R Maione, C Passananti
1Istituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Biopathologia Umana, Università di Roma La Sapienza, Italy.
Journal of Virology
|December 1, 1992
Summary
Polyomavirus mutants were engineered to replicate in C2 myoblasts. Mutations in the regulatory region or VP1 gene dictate replication ability in these specific mouse cells.
Area of Science:
- Virology
- Molecular Biology
- Cell Biology
Background:
- Murine polyomavirus (Py) typically replicates in differentiated cells.
- Undifferentiated C2 myoblasts are a model for studying viral replication.
- Understanding viral adaptation mechanisms is crucial for virology research.
Purpose of the Study:
- To isolate and characterize polyomavirus mutants capable of replicating in undifferentiated murine C2 myoblasts.
- To investigate the genetic basis for altered host cell tropism in polyomavirus.
Main Methods:
- Selection and characterization of polyomavirus mutants.
- Growth assays in C2 myoblasts and 3T6 fibroblasts.
- Analysis of regulatory region structure, including enhancer duplications.
- Genetic recombination experiments to assess phenotype.
- Identification of mutations in the VP1 coding region.
Main Results:
- Ten out of twelve selected polyomavirus mutants exhibited duplications in the regulatory region, specifically the enhancer A domain.
- One mutant class (PyMB3) showed a 91 bp enhancer duplication, creating a novel NF-1 transcription factor recognition motif.
- This regulatory region mutation, when recombined into a wild-type genome, retained the mutant phenotype.
- Other mutants possessed either a 30 bp enhancer duplication or a wild-type enhancer structure.
- These latter mutants had distinct 6 bp deletions in the VP1 coding region, which correlated with their ability to replicate in undifferentiated C2 myoblasts.
Conclusions:
- Polyomavirus replication in undifferentiated C2 myoblasts can be conferred by specific mutations.
- Enhancer duplications in the regulatory region, leading to altered transcription factor binding, are one mechanism.
- Deletions within the VP1 coding region represent another distinct mechanism for adapting to undifferentiated C2 myoblast replication.
- These findings highlight the genetic flexibility of polyomavirus in adapting to different cellular environments.