Coronavirus transcription mediated by sequences flanking the transcription consensus sequence

Area of Science:

• Virology
• Molecular Biology
• Genetics

Background:

• Murine coronavirus transcription is complex, involving subgenomic RNA synthesis.
• Defective interfering (DI) RNAs of mouse hepatitis virus (MHV) are valuable tools for studying viral transcription.
• Understanding transcription regulation is crucial for controlling viral replication.

Purpose of the Study:

• To investigate the influence of sequences flanking the MHV transcription consensus sequence on subgenomic RNA synthesis.
• To determine if the location or the flanking sequences themselves affect transcription efficiency.
• To identify potential transcription suppressive elements in naturally occurring MHV sequences.

Main Methods:

• Utilized a subgenomic DI RNA system derived from MHV.
• Inserted a 12-nucleotide transcription consensus sequence (including UCUAAAC) into DI RNAs at various locations.
• Analyzed the efficiency of subgenomic DI RNA synthesis based on flanking sequences.

Main Results:

• Insertion location did not affect subgenomic DI RNA synthesis efficiency.
• The sequences flanking the transcription consensus sequence determined the amount of subgenomic DI RNA produced.
• Naturally occurring flanking sequences from MHV genes 1-2, 2-3, and 6-7, as well as gene 1 cryptic consensus sequences, contained transcription suppressive elements.

Conclusions:

• Sequences flanking the transcription consensus sequence are critical regulators of MHV subgenomic RNA transcription.
• The presence of transcription suppressive elements in natural MHV flanking sequences can modulate viral gene expression.