Characterization of temperature-sensitive Akabane virus mutants and their roles in attenuation

Area of Science:

• Veterinary Virology
• Molecular Pathogenesis
• Bunyaviridae Research

Background:

• Akabane virus (AKAV) is a significant animal pathogen within the Orthobunyavirus genus.
• Limited research exists on AKAV's biological mechanisms and pathogenesis.
• Understanding AKAV virulence factors is crucial for animal health management.

Purpose of the Study:

• To generate temperature-sensitive (ts) mutants of AKAV.
• To investigate the role of viral genetic components in AKAV pathogenesis.
• To elucidate the molecular basis of AKAV virulence.

Main Methods:

• The virulent AKAV OBE-1 strain was treated with 5-fluorouracil to create ts mutants.
• Intracerebral inoculation of mice was performed to assess mutant virulence.
• Genomic sequencing and minireplicon systems were utilized to analyze viral RNA segments and protein activity.

Main Results:

• Twelve ts AKAV mutants were generated; three exhibited significantly reduced virulence (mortality <10%).
• Amino acid substitutions were identified in the M and L RNA segments of attenuated mutants, but not the S RNA segment.
• Minireplicon assays revealed temperature-dependent decreases in L protein activity for ts mutants.

Conclusions:

• The L RNA segment is implicated in AKAV virulence.
• These findings enhance the understanding of AKAV pathogenesis and viral gene function.
• The generated ts mutants serve as valuable tools for future AKAV research.