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A new cis-acting element for RNA replication within the 5' noncoding region of poliovirus type 1 RNA

K Shiroki1, T Ishii, T Aoki

  • 1Department of Microbiology, University of Tokyo, Japan.

Journal of Virology
|November 1, 1995
PubMed

Insights

Poliovirus Mahoney strain growth is temperature-sensitive in mouse cells, with reduced yields at 40°C due to defective RNA synthesis. A specific mutation (A to G at nucleotide 133) confers heat resistance by enabling efficient viral RNA replication in these cells.

Area of Science:

  • Virology
  • Molecular Biology
  • Genetics

Background:

  • Poliovirus type 1 Mahoney strain grows well in human HeLa cells and PVR-mouse cells at 37°C.
  • However, virus yield significantly decreases at 40°C in PVR-mouse cells, but not in HeLa cells.
  • This temperature sensitivity is linked to a defect in positive-strand RNA synthesis initiation.

Purpose of the Study:

  • To investigate the molecular mechanisms behind poliovirus's temperature-sensitive growth defect.
  • To identify mutations conferring heat resistance (Hr) in poliovirus Mahoney strain.
  • To understand the role of specific RNA regions in viral replication efficiency.

Main Methods:

  • Isolation of naturally occurring heat-resistant (Hr) mutants from poliovirus Mahoney strain.
  • Identification of mutation sites responsible for the Hr phenotype.
  • Analysis of viral growth and RNA synthesis at different temperatures in PVR-mouse cells.

Main Results:

  • A key mutation, adenine (A) to guanine (G) at nucleotide position 133 (nt 133) in the 5' noncoding region, was identified.
  • This A-to-G mutation at nt 133 conferred a heat-resistant (Hr) growth phenotype in PVR-mouse cells.
  • Only the mutant with guanine at nt 133 exhibited Hr growth, suggesting its critical role.

Conclusions:

  • The A-to-G mutation at nt 133 is crucial for poliovirus heat resistance in PVR-mouse cells.
  • Host cellular factors likely interact with the RNA region around nt 133 to regulate plus-strand RNA synthesis efficiency.
  • This interaction is key to overcoming the temperature-dependent replication defect.

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