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Virion assembly factories in the nucleus of polyomavirus-infected cells

Kimberly D Erickson1, Cedric Bouchet-Marquis, Katie Heiser

  • 1Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, Colorado, United States of America.

Plos Pathogens
|April 13, 2012
PubMed

Insights

Murine polyomavirus (PyV) assembly occurs in nuclear tubular structures, not dependent on PML protein. These findings reveal a new model for small DNA virus encapsidation.

Area of Science:

  • Virology
  • Cell Biology
  • Molecular Biology

Background:

  • Most DNA viruses replicate in the cell nucleus, but virion assembly sites remain unclear.
  • Promyelocytic leukemia nuclear bodies (PML-NBs) are implicated in the replication of several DNA viruses.

Purpose of the Study:

  • To investigate the nuclear sites of murine polyomavirus (PyV) virion assembly.
  • To determine the role of PML-NBs and associated proteins in PyV replication and assembly.

Main Methods:

  • Electron microscopy of infected mouse fibroblasts.
  • Immunohistochemistry and Fluorescence In Situ Hybridization (FISH) to detect viral and host proteins.
  • Analysis of PyV replication in PML-deficient cells and mice.

Main Results:

  • Tubular structures were observed in the nucleus adjacent to assembled PyV virions.
  • Co-localization of viral T-antigen (Tag), PyV DNA, and MRE11 protein near PML-NBs was confirmed.
  • PyV replication and virus assembly proceeded normally in PML-deficient cells and mice.

Conclusions:

  • PML protein is not essential for PyV replication or assembly, though it may indicate replication sites.
  • Observed nuclear tubular structures suggest a novel mechanism for small DNA virus encapsidation.
  • The study proposes a new model for the assembly of small DNA viruses.

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