Biochemical characterization of temperature-sensitive rabies virus mutants

Area of Science:

• Virology
• Molecular Biology
• Genetics

Background:

• Rabies virus is a significant public health concern.
• Temperature-sensitive (ts) mutants are valuable tools for studying viral replication and gene function.
• Understanding the molecular basis of rabies virus replication is crucial for developing effective control strategies.

Purpose of the Study:

• To biochemically characterize 70 temperature-sensitive (ts) mutants of rabies virus.
• To classify these mutants based on their protein and RNA synthesis at permissive and nonpermissive temperatures.
• To identify the location of the ts lesion within the viral replication cycle.

Main Methods:

• Infected cell cultures with ts rabies virus mutants at permissive (33°C) and nonpermissive (39.6°C) temperatures.
• Detected viral proteins using anti-N fluorescent antibodies.
• Assessed viral RNA synthesis using annealing techniques.
• Quantified viral protein synthesis at different temperatures and multiplicities of infection.

Main Results:

• Mutants were classified into three groups based on nucleocapsid protein (N) fluorescence at nonpermissive temperature: F+ (normal), F+- (faint), and F- (undetectable).
• F+ mutants exhibited normal viral protein and RNA synthesis, suggesting lesions in non-essential proteins.
• F+- and F- mutants showed defects in viral protein synthesis, indicating lesions affecting transcription and/or replication. F+- mutants retained some secondary transcription ability, while F- mutants did not.
• Primary transcription was normal in F- mutants at detectable levels.

Conclusions:

• Rabies virus ts mutants can be categorized based on their impact on viral protein and RNA synthesis.
• Mutants affecting transcription and/or replication present distinct phenotypes regarding viral gene expression.
• This classification aids in pinpointing specific genetic lesions within the rabies virus replication machinery.