Replication of murine coronavirus defective interfering RNA from negative-strand transcripts

Area of Science:

• Virology
• Molecular Biology
• Genetics

Background:

• Defective interfering (DI) RNAs are crucial for understanding viral replication mechanisms.
• Murine coronavirus mouse hepatitis virus (MHV) utilizes positive-strand DI RNA for replication and accumulation within infected cells.

Purpose of the Study:

• To investigate whether negative-strand transcripts of MHV DI RNA can initiate replication.
• To demonstrate the replication of DI RNA from introduced negative-strand transcripts in MHV-infected cells.

Main Methods:

• Constructed a plasmid with MHV DI RNA cDNA in reverse orientation downstream of a T7 promoter.
• Synthesized negative-strand DI RNA transcripts in vitro.
• Expressed negative-strand DI RNA transcripts in MHV-infected cells using a vaccinia virus T7 expression system.
• Analyzed DI RNA accumulation and sequences using molecular techniques.

Main Results:

• Positive-strand DI RNAs accumulated in cells transfected with negative-strand DI RNA transcripts.
• DI RNA replication was dependent on T7 polymerase and the T7 promoter.
• Sequence analysis confirmed the integrity of DI-specific sequences in replicated DI RNAs.
• Demonstrated that replication originated from the transfected negative-strand transcripts, not from potential positive-strand artifacts.

Conclusions:

• Positive-strand DI RNA synthesis can be initiated from introduced negative-strand transcripts in MHV-infected cells.
• This study provides the first evidence of DI RNA replication from transfected negative-strand DI RNA transcripts among all positive-stranded RNA viruses.