Single-stranded positive-sense RNA

Definition

Single-stranded positive-sense RNA is a type of viral RNA that can directly serve as messenger RNA (mRNA) for protein synthesis in host cells. This means that once the virus enters a host cell, its RNA can be immediately translated by the cell's ribosomes into viral proteins, facilitating rapid replication and infection. This characteristic is crucial for many plant viruses, as it enables them to hijack the host's cellular machinery effectively.

5 Must Know Facts For Your Next Test

1. Single-stranded positive-sense RNA viruses can replicate rapidly within host cells due to their ability to utilize the host's ribosomes immediately for protein synthesis.
2. Many important plant viruses belong to this category, including Tobacco mosaic virus (TMV) and Cucumber mosaic virus (CMV), which can lead to severe crop losses.
3. These viruses often have relatively simple genomes, which allows for quick evolution and adaptation to changing environments or host defenses.
4. In addition to coding for structural proteins, the RNA may also encode proteins that help suppress the host's immune response, allowing for prolonged infection.
5. The presence of single-stranded positive-sense RNA in plant viruses is a key factor in their transmission through vectors like insects, which can spread the virus from one plant to another.

Review Questions

• How does the structure of single-stranded positive-sense RNA contribute to its function in viral replication?
  • The structure of single-stranded positive-sense RNA allows it to function directly as mRNA upon entering a host cell. This means that the viral genome can be immediately translated by the host's ribosomes into viral proteins without needing additional steps. This rapid translation process facilitates quick replication and increases the chances of successful infection, making it a vital feature for many plant viruses.
• Discuss the significance of single-stranded positive-sense RNA in the context of plant viruses and their impact on agriculture.
  • Single-stranded positive-sense RNA is significant because it represents a major class of plant viruses that can quickly hijack host cellular machinery for replication. Viruses like Tobacco mosaic virus and Cucumber mosaic virus can cause substantial agricultural damage, leading to reduced crop yields and economic losses. Understanding this viral mechanism is crucial for developing strategies to manage and control outbreaks in agricultural settings.
• Evaluate the evolutionary advantages that single-stranded positive-sense RNA viruses might have over other types of viral genomes in relation to adaptability and infection efficiency.
  • Single-stranded positive-sense RNA viruses have several evolutionary advantages, including their ability to rapidly replicate within host cells due to direct translation into proteins. Their relatively simple genome organization allows for quick mutations and adaptations, helping them evade host defenses and exploit new hosts. This flexibility enhances their infection efficiency, allowing them to spread more easily through vectors like insects and increase their prevalence in diverse environments.

Related terms

Virion: A complete virus particle that consists of the viral genome enclosed in a protective protein coat, capable of infecting a host cell.

RNA-dependent RNA polymerase: An enzyme used by RNA viruses to replicate their RNA genome and transcribe their mRNA from the viral RNA template.

Plant viruses: Viruses that specifically infect plants, often causing significant agricultural damage and economic loss.