PKM2 Facilitates Classical Swine Fever Virus Replication by Enhancing NS5B Polymerase Function

Area of Science:

• Virology
• Molecular Biology
• Metabolic Regulation

Background:

• Viruses reprogram host metabolism for replication.
• Pyruvate kinase M2 (PKM2) is a glycolytic enzyme with non-canonical roles.
• The role of PKM2 in classical swine fever virus (CSFV) infection is unknown.

Purpose of the Study:

• To investigate the role of PKM2 in CSFV replication.
• To determine the interaction between PKM2 and CSFV proteins.
• To elucidate the mechanism by which PKM2 influences viral genome replication.

Main Methods:

• CSFV infection in PK-15 cells and piglet models.
• PKM2 expression analysis (in vitro and in vivo).
• PKM2 knockdown and overexpression studies.
• Co-immunoprecipitation and GST-pulldown assays to identify protein interactions.
• Dual-luciferase reporter assay to assess NS5B polymerase activity.
• Temporal analysis of viral replication.

Main Results:

• CSFV infection upregulates PKM2 expression, creating a proviral environment.
• PKM2 knockdown reduces CSFV proliferation; PKM2 overexpression enhances it.
• PKM2 directly interacts with CSFV NS5B protein.
• PKM2 modulates NS5B RNA-dependent RNA polymerase (RdRp) activity, with depletion reducing activity by 50%.
• PKM2 enhances CSFV RNA synthesis during the early replication cycle.

Conclusions:

• PKM2 is a proviral host factor for CSFV.
• PKM2 directly binds to CSFV NS5B, potentiating its RdRp activity.
• PKM2 bridges host metabolic adaptation and viral genome replication.
• This study uncovers a novel mechanism of CSFV-host interaction involving a glycolytic enzyme.