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Analysis of Group IV Viral SSHHPS Using In Vitro and In Silico Methods
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Viral protease-mediated polyprotein processing in human astroviruses.

David Noyvert1, Leandro X Neves2, Ksenia Fominykh1

  • 1Department of Pathology, Division of Virology, University of Cambridge, Cambridge, UK.

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Astroviruses use polyprotein processing for replication. This study maps key cleavage sites in human astrovirus 1 (HAstV1) and MLB2, revealing critical steps for virus life cycle and potential drug targets.

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Area of Science:

  • Virology
  • Molecular Biology
  • Proteomics

Background:

  • Positive-sense RNA viruses, including astroviruses, rely on polyprotein processing by proteases for viral replication.
  • Astroviruses infect intestinal and neuronal cells, necessitating a thorough understanding of their replication mechanisms.

Purpose of the Study:

  • To map the proteolytic cleavage sites within the nonstructural polyproteins of human astrovirus 1 (HAstV1) and neurotropic astrovirus MLB2.
  • To define the boundaries of individual protein products and identify conserved and divergent processing features between astrovirus strains.
  • To elucidate the role of polyprotein processing in viral replication complex formation and the astrovirus life cycle.

Main Methods:

  • N-terminomics analysis of infected cells.
  • Analysis of untagged overexpressed polyproteins.
  • Characterization of polyprotein precursors and cleavage-deficient mutants.

Main Results:

  • Identified dual cleavage sites at the N-terminus of HAstV1 and MLB2 proteases and at the C-terminus of the MLB2 protease.
  • Demonstrated processing of the hypervariable region and VPg in both astrovirus strains.
  • Revealed the critical role of polyprotein processing for replication complex formation and virus viability.

Conclusions:

  • Defined conserved and divergent polyprotein processing features between classical and non-classical astroviruses.
  • Established the essential role of polyprotein processing for astrovirus replication.
  • Highlighted the potential for targeting polyprotein processing for antiviral strategies.