Reovirus Low-Density Particles Package Cellular RNA.

Area of Science:

• Virology
• Molecular Biology
• Genomics

Background:

• Packaging of segmented viral RNA genomes requires precise coordination between viral proteins and RNA segments.
• Mammalian orthoreovirus (reovirus) is known to package either all or none of its ten double-stranded RNA genome segments, excluding host RNA.
• Reovirus produces both genome-containing virions and
• genomeless
• top component particles, but the RNA content of these particles, particularly regarding host RNA, remains uncharacterized.

Purpose of the Study:

• To investigate the RNA content of reovirus particles to understand reovirus packaging potential and mechanisms.
• To determine whether reovirus virions or top component particles package host RNA.

Main Methods:

• Utilized next-generation RNA sequencing to comprehensively analyze the RNA content of enriched reovirus particles.
• Compared RNA composition between reovirus virions and top component particles.

Main Results:

• Reovirus virions exclusively packaged viral double-stranded RNA, demonstrating highly selective genome packaging.
• Reovirus top component particles contained reduced amounts of viral double-stranded RNA and were significantly enriched for various host RNA species, particularly short, non-polyadenylated transcripts.
• Host RNA selection was independent of cellular RNA abundance and varied between reovirus strains, indicating a selective, non-random incorporation mechanism not solely dependent on the viral RNA polymerase.

Conclusions:

• Reovirus genome packaging into virions is exquisitely selective.
• Host RNA incorporation into top component particles is differentially selective and may be linked to inefficient viral RNA packaging processes.
• These findings provide critical insights into the distinct mechanisms governing RNA packaging in reovirus virions versus top component particles.