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The impact of altered polyprotein ratios on the assembly and infectivity of Mason-Pfizer monkey virus

Zdena Kohoutová1, Michaela Rumlová, Martin Andreánsky

  • 1Department of Biochemistry and Microbiology and the Center for Integrated Genomics, Institute of Chemical Technology, Prague, Czech Republic.

Virology
|December 9, 2008
PubMed

Insights

Altering retroviral polyprotein synthesis impacts virus assembly. Mutating frameshift sites in Mason-Pfizer monkey virus revealed that Gag-Pro-Pol is essential for particle formation and infectivity.

Area of Science:

  • Virology
  • Molecular Biology
  • Biochemistry

Background:

  • Retroviruses utilize frameshift mechanisms during polyprotein synthesis to regulate structural protein and enzyme ratios.
  • Understanding polyprotein precursor requirements is crucial for retrovirus assembly and replication.

Purpose of the Study:

  • To investigate the role of individual polyprotein precursors in retrovirus assembly.
  • To analyze the impact of altered polyprotein organization on Mason-Pfizer monkey virus (M-PMV) assembly and infectivity.

Main Methods:

  • Modified M-PMV polyprotein repertoire by mutating frameshift sites.
  • Created "Rous-like" (Gag-Pro, Gag-Pro-Pol) and "HIV-like" (Gag, Gag-Pro, Gag-Pro-Pol) polyprotein organizations.
  • Assessed particle assembly, Gag-Pro-Pol incorporation, morphogenesis, and infectivity of viral mutants.

Main Results:

  • "Rous-like" virus exhibited impaired assembly with no Gag-Pro-Pol incorporation.
  • "HIV-like" virus showed altered morphogenesis.
  • A mutant lacking Gag-Pro-Pol (expressing Gag and Gag-Pro) assembled intracellular particles similarly to wild-type M-PMV.
  • Gag-Pro-Pol alone did not form immature particles or process precursors.
  • "HIV-like" mutant retained fractional infectivity, while others were non-infectious.

Conclusions:

  • The Gag-Pro-Pol polyprotein is essential for M-PMV particle formation and infectivity.
  • Altering polyprotein organization significantly impacts retroviral assembly, morphogenesis, and infectivity.
  • Specific polyprotein precursors play distinct roles in the retroviral life cycle.

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