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Genetic stability of poliovirus insertion mutants with a foreign oligopeptide on the capsid surface
C Christodoulou1, I Pelletier, F Colbère-Garapin
1Unité de Virologie Médicale, Institut Pasteur, Paris.
Abstract:
The genetic stability of poliovirus mutants which carry a foreign oligopeptide on the surface of their capsid was studied (1) upon mutant isolation, (2) after serially diluted passages in cell cultures, and (3) in persistently infected cultures which have been recently developed. Viruses having a 3-codon insertion within the VP1 capsid protein-encoding region appeared to be extremely stable, except in the specific case of persistent infection. Viruses having a 6-codon insertion were slightly less stable. Point mutations and one recombination event were observed as soon as viruses were recovered and studied following plasmid transfection. Additional point mutations appeared within the insertion after 12 serially diluted passages in monkey kidney cells. Under all test conditions, the foreign insertion was never deleted from the virus genome.
Insights
Poliovirus mutants with foreign oligopeptides on their capsid proteins are genetically stable. Insertions within the VP1 gene remained intact, though some mutations occurred during passages and persistent infections.
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Poliovirus capsid proteins are key for viral structure and infectivity.
- Engineering foreign peptides onto viral surfaces can alter properties.
- Understanding genetic stability is crucial for vaccine development and viral vector applications.
Purpose of the Study:
- To assess the genetic stability of poliovirus mutants with foreign oligopeptide insertions.
- To investigate stability across different conditions: initial isolation, serial passages, and persistent infections.
Main Methods:
- Construction of poliovirus mutants with 3- and 6-codon insertions in the VP1 capsid protein gene.
- Analysis of viral genetic material after plasmid transfection and recovery.
- Serial dilution passages in monkey kidney cell cultures.
- Study of viruses in newly developed persistently infected cell cultures.
Main Results:
- Viruses with 3-codon insertions in VP1 were highly stable, except during persistent infections.
- Viruses with 6-codon insertions showed slightly reduced stability.
- Point mutations and a recombination event were observed upon initial recovery.
- Further point mutations arose within insertions after serial passages.
- Foreign insertions were never deleted from the viral genome under tested conditions.
Conclusions:
- Poliovirus capsid protein insertions demonstrate remarkable genetic stability.
- Persistent infections represent a specific condition where stability may be compromised.
- The VP1 gene is a viable site for stable foreign peptide insertion in poliovirus.