cis-Acting RNA packaging locus in the 115-nucleotide direct repeat of Rous sarcoma virus

Area of Science:

• * Virology
• * Molecular Biology
• * Genetics

Background:

• * Rous sarcoma virus (RSV) is an avian retrovirus known for causing tumors.
• * The v-src gene is essential for RSV's oncogenic properties.
• * Viral replication relies on the accurate assembly of viral components into new virions.

Purpose of the Study:

• * To investigate the role of a 115-nucleotide direct repeat sequence flanking the v-src gene in RSV replication.
• * To determine if this sequence is essential for the packaging of viral RNA into infectious virions.

Main Methods:

• * Construction and analysis of Rous sarcoma virus mutants lacking one or both copies of the 115-nucleotide repeat.
• * Posttransfection analysis of viral RNA transcription, processing, and translation.
• * Examination of virion composition following transfection with wild-type and mutant viral DNA.

Main Results:

• * Mutants lacking either one copy of the repeat replicated normally.
• * Mutants lacking both copies of the repeat could not produce infectious virions, despite normal RNA transcription and translation.
• * Viral RNA from mutants was not incorporated into virions, even when co-transfected with wild-type virus.

Conclusions:

• * The 115-nucleotide sequence acts as a cis-acting element required for the efficient packaging of viral RNA into Rous sarcoma virus particles.
• * This element is critical for the final stages of the viral replication cycle, specifically virion assembly.