What is the Difference Between dsRNA and ssRNA

The main difference between dsRNA and ssRNA is that dsRNA contains two strands of RNA whereas ssRNA contains a single copy of RNA.

dsRNA and ssRNA are two types of RNA with different numbers of RNA strands. Generally, these different types of RNA occur in the genomes of RNA viruses.  

Key Areas Covered

1. What is dsRNA
   • Definition, Characteristics, Importance
2. What is ssRNA
   • Definition, Characteristics, Importance
3. Similarities Between dsRNA and ssRNA
   • Outline of Common Features
4. Difference Between dsRNA and ssRNA
   • Comparison of Key Differences

Key Terms

dsRNA, ssRNA, RNA, RNA Viruses

What is dsRNA

dsRNA is the RNA with two strands and these two RNA strands are complementary to each other. Normally, dsRNA occurs in double-stranded RNA viruses. These double-stranded RNA viruses are a diverse group of viruses and their hosts range from humans, animals, plants, fungi, and bacteria. RNA-dependent RNA polymerase transcribes dsRNA into positive-sense RNA in dsRNA viruses. The forming messenger RNA can translate into viral proteins. In addition, RNA-dependent RNA polymerase undergoes replication of the dsRNA viral genome.

Figure 1: Rotavirus Structure

Moreover, rotaviruses are an example of double-stranded RNA viruses. Generally, it is the common cause of gastroenteritis in young children. Bluetongue virus is another double-stranded RNA virus, which is an economically significant pathogen for cattle and sheep.

What is ssRNA

ssRNA is the RNA molecule with a single copy of RNA. Generally, this type of RNA occurs in single-stranded RNA viruses. There are two types of single-stranded RNA that occur in the genome of single-stranded RNA viruses. They are in opposite senses called negative sense and positive sense. Here, positive-sense viral RNA is similar to mRNA. This type of RNA can be translated immediately by the host cell. In contrast, negative-sense RNA is complementary to mRNAs. Thus, it needs to be converted into positive-sense RNA by the RNA-dependent RNA polymerase prior to translation.

Figure 2: MERS Virus Structure

Therefore, ssRNA can be either positive sense or negative sense. In general, the purified positive sense RNA is infectious but, less infectious than the whole virus. However, the negative sense RNA is not infectious and needs to transcribe into positive-sense RNA in order to be infectious.

Similarities Between dsRNA and ssRNA

• The dsRNA and ssRNA are different types of RNA that occur in the genomes of RNA viruses.
• These RNA types are made up of RNA nucleotides.
• Moreover, these RNA types undergo transcription and translation to synthesize proteins of RNA viruses.

Difference Between dsRNA and ssRNA

Definition

dsRNA refers to the RNA molecules with two complementary strands while ssRNA refers to the RNA molecules with a single strand.

Significance

Moreover, dsRNA occurs in double-stranded RNA viruses while ssRNA occurs in single-stranded RNA viruses.  

Transcription

Usually, RNA-dependent RNA polymerase transcribes dsRNA while only the negative sense RNA undergoes transcription. 

Examples

Rotavirus is an example of a double-stranded RNA virus with dsRNA while Hepatitis C virus, West Nile virus, dengue virus, and MERS are examples of positive-sense single-stranded RNA viruses.

Conclusion

In brief, dsRNA is the RNA molecule with two RNA strands complementary to each other. Usually, this type of RNA occurs in the genome of the double-stranded RNA viruses. Some examples of double-stranded RNA viruses include rotavirus. ssRNA, on the other hand, is the single RNA molecule that occurs in the genome of single-stranded RNA viruses. There are two types of ssRNA molecules in their genome. They are the positive sense ssRNA and the negative sense ssRNA. Here, the positive sense ssRNA is the same as mRNA and can readily undergo translation. But negative sense ssRNA requires transcription prior to translation. However, the main difference between dsRNA and ssRNA is their number and the type of RNA molecules.

References:

1. Weber F, Wagner V, Rasmussen SB, Hartmann R, Paludan SR. Double-stranded RNA is produced by positive-strand RNA viruses and DNA viruses but not in detectable amounts by negative-strand RNA viruses. J Virol. 2006 May;80(10):5059-64. doi: 10.1128/JVI.80.10.5059-5064.2006. PMID: 16641297; PMCID: PMC1472073

Image Courtesy:

1. “Rotavirus virion” By ViralZone – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “3D medical animation coronavirus structure” By https://www.scientificanimations.com – Own Work (CC BY-SA 4.0) via Commons Wikimedia