(-)ssRNA

Definition

(-)ssRNA refers to negative-sense single-stranded ribonucleic acid, which is a type of viral genome that must be converted into a positive-sense RNA before it can be translated into proteins. This conversion is essential for the replication and functioning of viruses, as negative-sense RNA cannot be directly translated by the host's ribosomes. The understanding of (-)ssRNA is vital for categorizing certain families of viruses that utilize this genetic material and for comprehending their unique replication strategies.

5 Must Know Facts For Your Next Test

1. Viruses with (-)ssRNA genomes include important pathogens like influenza virus, rabies virus, and Ebola virus.
2. To replicate, (-)ssRNA viruses must first convert their negative-sense RNA into positive-sense RNA using RNA-dependent RNA polymerase.
3. The structure of (-)ssRNA is usually helical, and these viruses often have enveloped forms which aid in their entry into host cells.
4. Many (-)ssRNA viruses have segmented genomes, meaning their genetic material is divided into separate pieces, which can lead to reassortment and increased genetic diversity.
5. The immune response to (-)ssRNA viruses can involve recognition by pattern recognition receptors (PRRs), which detect viral RNA and initiate antiviral responses.

Review Questions

• How do (-)ssRNA viruses differ from positive-sense RNA viruses in terms of their replication process?
  • (-)ssRNA viruses differ from positive-sense RNA viruses primarily in the requirement for their genome to be converted into positive-sense RNA before translation can occur. While positive-sense RNA can be directly translated by host ribosomes, (-)ssRNA must first utilize an enzyme called RNA-dependent RNA polymerase to produce the positive-sense strand. This step is critical for their ability to produce proteins necessary for viral replication and assembly.
• Discuss the significance of RNA-dependent RNA polymerase in the life cycle of (-)ssRNA viruses.
  • RNA-dependent RNA polymerase is crucial in the life cycle of (-)ssRNA viruses as it catalyzes the conversion of negative-sense RNA into positive-sense RNA. This enzyme enables the virus to replicate its genetic material efficiently, allowing for the production of viral proteins and new virions. Without this polymerase, (-)ssRNA viruses would not be able to effectively propagate within a host cell, highlighting its importance in their replication strategy.
• Evaluate the impact of segmented genomes on the evolution and adaptability of (-)ssRNA viruses.
  • Segmented genomes greatly enhance the evolutionary potential and adaptability of (-)ssRNA viruses by allowing genetic reassortment when two different strains co-infect a host cell. This process can result in new viral strains with varied properties, including altered pathogenicity or resistance to antiviral treatments. The ability to rapidly acquire new traits through reassortment contributes to the ongoing challenges in controlling outbreaks caused by these viruses, making them a significant concern in public health.

Related terms

Positive-sense RNA: A type of RNA that can be directly translated into proteins by the ribosomes of the host cell.

RNA-dependent RNA polymerase: An enzyme that synthesizes RNA from an RNA template, crucial for the replication of RNA viruses.

Viral genome: The complete set of genetic material (DNA or RNA) present in a virus, which encodes the information necessary for its replication and assembly.