Evolution of multiple genome mutations during long-term persistent infection by vesicular stomatitis virus

Area of Science:

• Virology
• Molecular Biology
• Cell Biology

Background:

• Persistent viral infections can alter viral evolution.
• Defective interfering (DI) particles play a role in viral dynamics.
• Vesicular stomatitis virus (VSV) provides a model for studying viral persistence.

Purpose of the Study:

• To investigate the long-term evolutionary changes in VSV and its associated DI particles during persistent infection.
• To compare viral evolution in persistent versus acute infection models.

Main Methods:

• Establishing persistent infection of BHK21 cells with VSV and DI particles.
• Monitoring viral RNA genomes using oligonucleotide mapping over five years.
• Passaging virus in acute infections (in vitro and in vivo) for comparison.

Main Results:

• Persistent VSV infection showed significant oligonucleotide map changes in the viral RNA genome after one year, with extensive evolution by 3.5 and 5 years.
• Acute infections did not result in detectable genomic changes.
• The initial DI particles were replaced by a dynamic population of DI particles with diverse and altered oligonucleotide maps.
• Mutations in persistent VSV led to stable, poorly replicating, temperature-sensitive, small plaque mutants.

Conclusions:

• The genomes of both infectious VSV and its DI particles undergo continuous evolutionary change during long-term persistence.
• The intracellular environment of persistently infected cells promotes rapid and continuous viral evolution.
• These evolutionary changes result in stable viral mutants that do not revert to wild-type under acute infection conditions.