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Molecular basis for interference of defective interfering particles of pseudorabies virus with replication of
Abstract:
Serial passage of pseudorabies virus (PrV) at high multiplicity yields defective interfering particles (DIPs), but the sharp cyclical increases and decreases in titer of infectious virus that are observed upon continued passage at high multiplicity of most DIPs of other viruses are not observed with DIPs of PrV (T. Ben-Porat and A. S. Kaplan, Virology 72:471-479). We have studied the dynamics of the interactions of the virions present in a population of DIPs to assess the cis functions for which the genomes of the DIPs are enriched. The defective genomes present in one population of DIPs, [PrV(1)42], replicate preferentially over the nondefective genomes present in that virion population at early stages of infection, indicating that the DIP DNA is enriched for sequences that can serve as origins of replication at early stages of infection. This replicative advantage of the DIP DNA is transient and disappears at later stages of infection. The defective DNA does not appear to be encapsidated preferentially over the nondefective DNA present in this virion population, which might indicate that it is not enriched for cleavage-encapsidation sites. However, the nondefective DNA in the DIP virion population has become modified and has acquired reiterations of sequences originating from the end of the unique long (UL) region of the genome. Furthermore, both the infectious and defective genomes present in the DIP population compete for encapsidation more effectively than do the genomes of standard PrV. These results indicate that the defective genomes in the population of virions studied are enriched not only for an origin of replication but probably also for sequences necessary for efficient cleavage-encapsidation. Furthermore, the nondefective genomes present in this population of DIPs have also been modified and have acquired the ability to compete with the defective genomes for cleavage-encapsidation.
Insights
Pseudorabies virus (PrV) defective interfering particles (DIPs) show unique replication dynamics. PrV DIP genomes are enriched for replication origins and cleavage-encapsidation sites, enhancing viral propagation and modification.
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Serial passage of pseudorabies virus (PrV) at high multiplicity generates defective interfering particles (DIPs).
- Unlike other viruses, PrV DIPs do not exhibit cyclical increases and decreases in infectious virus titer.
- Understanding the cis-acting functions of PrV DIP genomes is crucial for explaining their unique behavior.
Purpose of the Study:
- To investigate the dynamics of virion interactions within a PrV DIP population.
- To identify cis-acting functions for which PrV DIP genomes are enriched.
- To elucidate the mechanisms behind the altered replication and encapsidation properties of PrV DIPs.
Main Methods:
- Analysis of viral populations derived from serial passage of PrV.
- Comparative study of replication and encapsidation efficiencies of defective and nondefective PrV genomes.
- Assessment of genomic modifications, including sequence reiterations, in PrV DIPs.
Main Results:
- Defective PrV DIP genomes exhibit preferential replication over nondefective genomes early in infection, indicating enrichment for origins of replication.
- This replicative advantage is transient and diminishes at later stages.
- Both defective and nondefective PrV genomes within the DIP population compete more effectively for encapsidation than standard PrV genomes, suggesting enrichment for cleavage-encapsidation sites and acquisition of modified sequences.
Conclusions:
- PrV DIP genomes are enriched for both replication origins and sequences essential for efficient cleavage-encapsidation.
- Nondefective genomes within the PrV DIP population have undergone modifications, acquiring reiterations from the unique long (UL) region and enhanced competitive ability for encapsidation.
- These genomic modifications contribute to the unique dynamics and propagation characteristics of PrV DIPs.