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Defective influenza A virus generated entirely from plasmids: its RNA is expressed in infected mouse lung and

S D Duhaut1, N J Dimmock

  • 1Department of Biological Sciences, University of Warwick, Coventry, UK CV4 7AL.

Journal of Virological Methods
|February 5, 2003
PubMed

Insights

Molecularly cloned defective influenza viruses expressing defined defective RNAs show antiviral activity. Passage in eggs enhanced their ability to delay disease onset in mice challenged with influenza A virus.

Area of Science:

  • Virology
  • Immunology

Background:

  • Naturally occurring defective influenza viruses exhibit antiviral properties and can protect mice from lethal influenza infections.
  • Existing defective virus preparations lack defined RNA sequences, hindering dose-response studies and mechanistic investigations.

Purpose of the Study:

  • To produce molecularly cloned defective influenza viruses with defined defective RNAs for in vivo studies.
  • To evaluate the antiviral activity and therapeutic potential of these defined defective viruses in a mouse model.

Main Methods:

  • Transfection of Vero cells with DNA encoding cloned defective RNAs and helper virus plasmids.
  • Production and UV-irradiation of defective virus preparations.
  • Intranasal inoculation of mice with defective viruses and subsequent challenge with influenza A virus (WSN/H1N1).
  • Detection of defective RNAs by RT-PCR and assessment of disease progression and mortality.

Main Results:

  • Vero cell-derived defective viruses (POLI-220 and POLI-317) did not modulate disease in mice.
  • A single passage in embryonated eggs significantly delayed disease and death onset in WSN-infected mice.
  • Sequence analysis confirmed the integrity of the defective RNAs after passage in vivo.

Conclusions:

  • Molecularly cloned defective influenza viruses with defined RNAs can be generated and propagated.
  • Passage in embryonated eggs is crucial for enhancing the in vivo antiviral activity of these defined defective viruses.
  • This advancement enables precise in vivo studies of the influenza interference phenomenon using defined defective RNAs.

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