APR 10, 2017 5:54 PM PDT

An Examination of Giant Virus Evolution

WRITTEN BY: Carmen Leitch

Viruses are quite simply everywhere in our environment; it’s estimated that they even outnumber bacteria with an estimated population around 1031. Giant viruses were first described only a few years ago, upending the idea that viruses are small and simple.  They have interesting codes in their massive genomes, including the ability to make proteins. Researchers at the U.S. Department of Energy Joint Genome Institute (DOE JGI), have now found another group of giant viruses they called Klosneuviruses. The video below summarizes the work, which was reported in Science.

This new virus showed the researchers that the massive genome of the virus was built over time as a smaller virus acquire new features and continued adding them in. "The discovery presents virus evolution for us in new ways, vastly expanding our understanding of how many essential host genes viruses can capture during their evolution," explained one co-author of the work Eugene Koonin, a evolutionary and computational biologist at the National Institutes of Health. "Since protein synthesis is one of the most prominent hallmarks of cellular life, it shows that these new viruses are more 'cell-like' than any virus anyone has ever seen before."

By studying the genome of a virus picked up in a wastewater treatment plant, the investigators found that this one had features that were unique among viruses. "We expected genome sequences of nitrifying bacteria in the microcolony sequence data," Woyke said. "Finding a giant virus genome took the project into a completely new and unexpected, yet very exciting direction." 

Related: Another Giant Virus Emerges From Melting Siberia

The virus genome featured over 20 tRNAs and a variety of translation factors and tRNA modifying enzymes, previously unseen in viruses. This virus likely added parts to its genome after infecting different hosts. "In this scenario, a smaller virus infected different eukaryote hosts and picked up genes encoding translational machinery components from independent sources over long periods of time through piecemeal acquisition," explained lead author Tanja Woyke, DOE JGI Microbial Genomics Program.

The researchers used a metagenomic analysis to learn that the Klosneuvirus group derived from a novel viral lineage linked to Mimiviruses. "Mining sequence data in DOE JGI's Integrated Microbial Genomes & Microbiomes system, which houses thousands of metagenomes, allowed us to find evolutionary relatives of our Klosneuvirus," said first author and JGI postdoctoral researcher Frederik Schulz. "This amounts to evidence that these giant viruses are not a separate domain of life, and they did not derive from a cellular ancestor.

 This is probably not the last we’ve heard of giant viruses, however, and the biological function of these genes is still not known. Koonin is awaiting the discovery of even more giant viruses through metagenomic data. "I'm quite confident that the current record of the genome size of giant viruses will be broken," he said. "We are going to see the real Goliaths of the giant virus world.”

You can check out a talk from Schulz on his work in this video.

Sources: AAAS/Eurekalert! via DOE JGI, Science

About the Author
  • Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
APR 06, 2021
Clinical & Molecular DX
Radioactive Antibody Illuminates Fungal Lung Infections
APR 06, 2021
Radioactive Antibody Illuminates Fungal Lung Infections
  An international team of scientists has pioneered a new procedure to diagnose lung disease caused by common mold. ...
APR 12, 2021
Cell & Molecular Biology
Deep Subsurface Microbes Are "Living Fossils"
APR 12, 2021
Deep Subsurface Microbes Are "Living Fossils"
Researchers were shocked when they saw the results of a genetic analysis comparing various microbes from around the worl ...
MAY 03, 2021
Cell & Molecular Biology
Are Retrons the Next CRISPR?
MAY 03, 2021
Are Retrons the Next CRISPR?
After being identified in the 1980s, it was thought that retrons were just an odd feature of some bacterial cells. But e ...
MAY 14, 2021
Earth & The Environment
New species of cyanobacteria discovered
MAY 14, 2021
New species of cyanobacteria discovered
A new study published in Current Biology details the finding of a previously unidentified species of cyanobacteria. The ...
MAY 27, 2021
Neuroscience
Research Less Likely to Be True is Cited More
MAY 27, 2021
Research Less Likely to Be True is Cited More
Researchers from the University of California San Diego have found that non-replicable data is cited 153 times more ofte ...
JUN 14, 2021
Coronavirus
COVID-19 May Cause Diabetes
JUN 14, 2021
COVID-19 May Cause Diabetes
Reporting in Cell Metabolism, an international team of researchers has suggested that COVID-19 has caused diabetes in so ...
Loading Comments...