Using an advanced bioinformatics tool named BEREN, researchers from the University of Miami found more than 600 viral genomes from global metagenomic datasets, with 230 of them being complete and unknown. The tool allowed the team to mine environmental DNA samples with greater accuracy than ever before, pulling out complete viral genomes from complex ocean data. It found some significant viral activity even in under-studied regions like the Baltic Sea, with potential to reshape their geographical reach and ecological application.
Surprisingly, these giant viruses encode 530 new functional proteins, including nine linked to photosynthesis — an ability once thought confined to plants and algae — suggesting that viruses are not just agents of infection but are biochemical engineers capable of restructuring the very metabolisms of their hosts. They belong primarily to the nucleocytoplasmic large DNA viruses (NCLDVs) with pristine genetic toolkits. And, some of them have genome sizes exceeding those of bacteria.
Viral architects of ocean
Beyond revising the longstanding belief that viruses are biologically inert parasites, these giants emerge as masters of bioengineering, capable of reprogramming their hosts at the molecular level. For instance, Phytoplankton — the microscopic marine plants that form the base of the food chain and generate around 50% of the planet’s oxygen — are frequent hosts of these giant viruses. Rather than simply killing their hosts, the study found that the giant viruses hijack their host’s energy and metabolic systems, sometimes extending the survival period to maximize replication.
The manipulation has startling effects across the entire marine ecosystem. When giant viruses abruptly halt phytoplankton blooms, the repercussions ripple upward through zooplankton, fish populations, and even commercial fisheries. Phytoplankton are central players in Earth’s carbon cycle, drawing in CO₂ during photosynthesis and transferring it to the deep sea when they die. By influencing when and how these blooms end, viruses can affect how much carbon is sequestered from the atmosphere, thereby potentially shaping global climate outcomes.
“Giant viruses are often the main cause of death for many phytoplankton,” said Mohammad Moniruzzaman, a co-author of the study. “These organisms are central to ocean ecosystems and global food security. When viruses take them down, there’s a cascade effect.”
The findings also challenge hitherto-held biological beliefs. With genome sizes exceeding 2.5 million base pairs and housing over a thousand genes, defy the influenza which carries just eight genes. Essentially, these viruses blur the line between virus and microbe. Some viral genes discovered even hint at the ability to perform DNA repair and protein synthesis — functions previously thought to be exclusive to living cells.
Strikingly, more than 88% of the proteins encoded by these viral genomes are completely novel, with no known analogues in current genetic databases known to scientists so far. What scientists have found suggests a vast, largely untapped genetic reservoir floating in our oceans.
Contrary to what the scientific community has traditionally regarded viruses as peripheral actors, the discovery makes the case for a viral-centric view of ecology. As Minch, the lead author, noted, “This is not just an expansion of known viral families. It’s a rethinking of how viruses evolved and how they continue to influence life on Earth.”
Influencers of future applications
If not immediate climate changes, the discovery raises questions whether such complex viral systems have played a role in the origin of life. Can they be repurposed in biotechnology since some researchers have already undertaken applications such as engineering super-algae to trap more CO₂ or using virus-based systems to influence energy pathways in synthetic cells.
Another concern is how these systems might shift as ocean conditions continue to undergo climate change. With warming waters, changing pH levels, and increased human interference, the balance between phytoplankton and their viral predators may tip in unpredictable ways. These viruses could become crucial in two ways — either increasing ecological disruptions or helping ecosystems adapt.
The discovery also sets the stage for a new generation of marine science focused on viruses as agents of ecological design, rather than destruction. In fact, it opens the door to engineering viruses to enhance oceanic carbon sequestration by controlling when and how phytoplankton or fish die and sink, potentially offering a novel climate intervention tool.
In biotechnology, their metabolic genes could be mined for better applications in biofuels, industrial fermentation, or high-efficiency photosynthesis. Since 88% of their protein families are previously unknown, it opens a vast untapped source of molecules that could be developed into new antibiotics, antivirals, or immune-modulating therapies.
In medicine, these virus-derived tools might even surpass CRISPR in precision genome editing or be adapted as highly specific drug delivery systems. Their unique evolutionary position could help scientists reconstruct early life and uncover transitional forms, perhaps strengthening the companies such as Colossal Biosciences to successfully revive “extinct” species, whether for good or bad.
Moreover, these viruses’ ability to manipulate marine ecosystems hints at future applications in managing fisheries, combating harmful algal blooms, or restoring ecological balance. The discovery may also mark the beginning of a new era where viruses, long seen as threats, become essential partners in meeting humanity’s most pressing challenges — from climate resilience to next-generation medicine.