THE MAJOR CONCEPT, According to a new study published in the journal Science, an investigation of the genetic material in the ocean has uncovered thousands of previously unknown RNA viruses and increased the number of phyla, or biological groups, of viruses thought to exist.
The illnesses caused by RNA viruses are well-known, ranging from the common cold to COVID-19. Plants and animals that are essential to humans are also infected. RNA, not DNA, is used to transport the genetic information of these viruses. The evolution of RNA viruses is substantially faster than that of DNA viruses. While hundreds of thousands of DNA viruses have been identified in natural environments, RNA viruses have received less attention.
Viruses, unlike humans and other cell-based animals, lack distinctive short sequences of DNA that may operate as a genetic bar code, according to experts. Trying to identify between various virus species in the wild without this bar code can be difficult. We wanted to find the gene that codes for a specific protein that permits a virus to reproduce its genetic material to get past this barrier. It’s the single protein that all RNA viruses have in common, and it’s crucial to their ability to reproduce. Small changes in the gene that codes for the protein in each RNA virus, however, can help differentiate one kind of virus from another.
As a result, we combed through a global database of RNA sequences from plankton gathered during the Tara Oceans mission’s global research project, which lasted four years. Any aquatic creature that is tiny enough to swim against the stream is considered plankton. They’re an important element of the ocean food chain and RNA virus hosts. Over 44,000 genes that code for the viral protein were discovered as a result of our screening.
The next step was to figure out the evolutionary relationships between these genes. The more closely two genes resembled each other, the more probable viruses possessing those genes were connected. The genetic signposts identifying where new viruses may have broken off from a common ancestor had been lost to time since these sequences had developed so long ago (perhaps predating the first cell).
Machine learning, a type of artificial intelligence, allowed us to methodically arrange these sequences and spot discrepancies more objectively than if the work had been completed manually. We discovered 5,504 new marine RNA viruses, bringing the total number of known RNA virus phyla to ten. Two of the new phyla were found to be exceptionally numerous throughout broad marine regions, with regional preferences in either temperate and tropical seas (the Taraviricota, named after the Tara Oceans voyages) or the Arctic Ocean (the Arctiviricota).
Taraviricota, we believe, may be the long-sought missing link in the evolution of RNA viruses, uniting two separate known branches of RNA viruses that differ in how they reproduce. WHY DOES IT MATTER? These new sequences aid scientists in better understanding not only RNA virus evolution, but also the evolution of early life on Earth. RNA viruses may produce devastating infections, as the COVID-19 pandemic has demonstrated. RNA viruses, on the other hand, play an important role in ecosystems because they may infect a broad range of species, including bacteria that have a chemical impact on habitats and food webs.
Identifying where these RNA viruses dwell across the world will help researchers better understand how they influence the creatures that drive many of the ecological systems that keep our planet running. In addition, as genomic databases develop, our research has enhanced methods that can assist researchers in cataloging novel viruses.
WHAT IS STILL UNKNOWN, despite the discovery of several novel RNA viruses, determining which creatures they infect remains difficult? Because of their genetic complexity and technical restrictions, researchers are now confined to largely pieces of incomplete RNA virus genomes. The next step would be to determine which genes are missing and how they have altered through time. Scientists may be able to learn more about how these viruses act if these genes are discovered.