Related Experiment Video
Updated: May 21, 2026
15:49
Reverse Genetics to Engineer Positive-Sense RNA Virus Variants
Published on: June 9, 2022
Expanding networks of RNA virus evolution
Eugene V Koonin1, Valerian V Dolja
1National Center for Biotechnology Information, National Institutes of Health, Bethesda, MD 20894, USA. koonin@ncbi.nlm.nih.gov
BMC Biology
|June 22, 2012
Summary
This study reveals double-stranded RNA (dsRNA) viruses originate from multiple positive-strand RNA virus groups. It highlights extensive horizontal gene transfer, suggesting a network-like viral evolution and unexpected discoveries in viral genomics.
Area of Science:
- Virology
- Evolutionary Biology
- Genomics
- Mycology
Background:
- Double-stranded RNA (dsRNA) viruses are a significant component of the virosphere, with their evolutionary origins and diversification not fully understood.
- Previous hypotheses suggested a polyphyletic origin for dsRNA viruses, but comprehensive genomic evidence has been limited.
- Understanding viral evolution, including gene transfer and origins, is crucial for comprehending viral diversity and host interactions.
Purpose of the Study:
- To investigate the evolutionary origins of double-stranded RNA (dsRNA) viruses through phylogenomic analysis.
- To explore the extent of horizontal gene transfer among diverse viral groups.
- To identify novel viral lineages and genomic structures, including potential archaeal RNA viruses and RNA-DNA virus hybrids.
Main Methods:
- Sequencing and analysis of two new dsRNA virus genomes from fungi.
- Extensive phylogenomic analysis incorporating existing dsRNA virus genomic data.
- Comparative genomics to identify patterns of gene sharing and evolutionary relationships.
Main Results:
- The study provides genomic support for the polyphyletic origin of dsRNA viruses, originating from different groups of positive-strand RNA viruses.
- Evidence of extensive horizontal gene transfer was observed between diverse viruses, supporting a network-like model of viral evolution over a strictly tree-like model.
- The research uncovered the first putative archaeal RNA virus and a novel RNA-DNA virus hybrid, expanding the known diversity of viral genomes.
Conclusions:
- The findings reinforce the complex and non-monophyletic evolutionary history of dsRNA viruses.
- Viral evolution is characterized by significant horizontal gene transfer, leading to a reticulated network of relationships.
- RNA viral genomics continues to yield unexpected discoveries, highlighting the vast unexplored potential of viral diversity across different domains of life.
Related Concept Videos
00:36Viral Mutations
A mutation is a change in the sequence of bases of DNA or RNA in a genome. Some mutations occur during replication of the genome due to errors made by the polymerase enzymes that replicate DNA or RNA. Unlike DNA polymerase, RNA polymerase is prone to errors because it is not capable of “proofreading” its work. Viruses with RNA-based genomes, like HIV, therefore accrue mutations faster than viruses with DNA-based genomes. Because mutation and recombination provide the raw material for adaptive...
01:29Viruses with RNA Genomes
RNA viruses are categorized into positive-strand, negative-strand, or double-stranded groups based on their genomic structure and replication mechanisms. This classification dictates how they exploit host cellular machinery for protein synthesis and replication. Some RNA viruses also utilize reverse transcription as part of their life cycle, further diversifying their replication strategies.Positive-Strand RNA VirusesPositive-strand RNA viruses have genomes that function directly as messenger...
01:26Size and Structure of Viral Genomes
Viral genomes exhibit remarkable diversity in size, structure, and composition, influencing their replication strategies and interactions with host cells. These genomes consist of either DNA or RNA and may be linear or circular. Additionally, they can be single-stranded or double-stranded, with each configuration affecting how the virus propagates within a host. RNA viruses, for instance, generally have smaller genomes than DNA viruses, a factor that contributes to their high mutation rates and...
00:43Bacterial RNA Polymerase
Unlike eukaryotes, bacteria use a single RNA Polymerase (RNAP) to transcribe all genes. The different subunits of bacterial RNAPhave distinct functions. The multisubunit structure of the bacterial RNAP helps the enzyme to maintain catalytic function, facilitate assembly, interact with DNA and RNA, and self-regulate its activity.
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
01:10Retrovirus Life Cycles
Retroviruses have a single-stranded RNA genome that undergoes a special form of replication. Once the retrovirus has entered the host cell, an enzyme called reverse transcriptase synthesizes double-stranded DNA from the retroviral RNA genome. This DNA copy of the genome is then integrated into the host’s genome inside the nucleus via an enzyme called integrase. Consequently, the retroviral genome is transcribed into RNA whenever the host’s genome is transcribed, allowing the retrovirus to...
01:29Viruses of Archaea
Archaeal viruses play a crucial role in the ecosystems of extremophilic archaea, particularly those belonging to the phyla Euryarchaeota and Crenarchaeota. By shaping host evolution and facilitating gene transfer, these viruses influence microbial communities and contribute to genetic diversity in extreme environments. The archaea they infect thrive in acidic hot springs and hydrothermal vents characterized by high temperatures and low pH. Archaeal viruses exhibit remarkable structural...