Scientists have just discovered hundreds of new giant viruses, in a comprehensive study covering oceans across the globe.
The team behind the study, marine biologist Benjamin Minch and virologist Mohammad Moniruzzaman from the University of Miami, used bespoke computer software to identify the genomes of microbes in seawater samples – including 230 giant viruses previously unknown to science.
Identifying these viruses is a crucial part of understanding life in the ocean, and in particular the survival of marine organisms known as protists – including algae, amoeba, and flagellates.
“By better understanding the diversity and role of giant viruses in the ocean and how they interact with algae and other ocean microbes, we can predict and possibly manage harmful algal blooms, which are human health hazards in Florida as well as all over the world,” says Moniruzzaman.
Thanks to rapid recent advances in genome databases, analysis instruments, and computer programs such as the ones used here, the process of discovering giant viruses is now significantly easier than it used to be – giving scientists fresh insights into how these viruses spread and behave.
For example, giant viruses are often responsible for the death of phytoplankton, the tiny, photosynthesizing organisms commonly found in oceans, lakes, and rivers. These organisms are crucial to marine life and food chains, and produce huge amounts of Eartyh’s oxygen, so knowing more about the viruses that prey on them could help in protection efforts.
In addition to the 230 new giant viruses, the study also identified 569 new functional proteins, including nine involved in photosynthesis. It seems that in some cases, the viruses are able to hijack the photosynthesis functions of their hosts, in order to get the energy they need to survive.
“We discovered that giant viruses possess genes involved in cellular functions such as carbon metabolism and photosynthesis – traditionally found only in cellular organisms,” says Minch.
“This suggests that giant viruses play an outsized role in manipulating their host’s metabolism during infection and influencing marine biogeochemistry.”
The researchers were able to fit the giant viruses they discovered into two existing virus orders: Imitervirales and Algavirales. These groups use different infection strategies, with Imitervirales the most genetically complex, indicating a more flexible ‘life strategy’ that potentially allows the virus to survive in a wider variety of hosts.
We know we’ve only really just scratched the surface when it comes to getting the full picture of the life that lives in the oceans: each drop of seawater is teeming with viruses, and marine life actually helps protect us from many of them.
And there should be a lot more to come too, using the methods outlined in this particular study. There are vast numbers of viruses still waiting to be discovered and cataloged – and to be put into context with ocean ecosystems and health.
“This study allowed us to create a framework to improve existing tools for detecting novel viruses that could aid in our ability to monitor pollution and pathogens in our waterways,” says Minch.
The research has been published in Nature npj Viruses.
