Latent endogenous giant viruses drive active infection and inheritance in a multicellular algal host.
Duchêne C, Craig RJ, Martinho C, Luthringer R, Agullo F
Plant Virology
Seaweeds blanketing rocky shorelines and kelp forests are quietly harboring sleeping viruses that can reactivate — and understanding how algae manage these hidden infections could reshape how we think about disease in the ocean plants that produce half the world's oxygen.
Many organisms carry old viral DNA tucked into their own genes, like fossils of ancient infections. Researchers found that in a type of brown seaweed, these viral fossils aren't really dead — they can switch back on under the right conditions, like changes in temperature, and start producing new viruses again. The viruses can then spread to other seaweed cells and are also passed down to the next generation through seeds, meaning the seaweed inherits both the virus and the ability to reactivate it.
Key Findings
Full-length, functional phaeovirus genomes were found fully integrated and transcriptionally active within the brown alga Ectocarpus host genome
Viral reactivation is triggered by specific environmental and developmental cues, including temperature shifts, demonstrating precise host-controlled regulation
Using CRISPR-Cas and classical genetics, the team confirmed these viral elements are stably inherited through the germline and can spread both vertically (to offspring) and horizontally (to neighboring cells)
chevron_right Technical Summary
Scientists discovered that giant viruses hiding inside the DNA of a marine alga can wake up, replicate, and spread — both to offspring and to neighboring cells. This overturns the idea that viral DNA buried in a host genome is just harmless genetic baggage.
Abstract Preview
Endogenous viral elements inserted in host genomes are often regarded as inert relics of past infections. Whether they can retain infective potential and contribute to active viral cycles has remai...
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Brown algae are a large group of photoautotrophic, multicellular SAR comprising the class Phaeophyceae. They include many seaweeds located in colder waters of the Northern Hemisphere. Brown algae are the major seaweeds of the temperate and polar regions. Many brown algae, such as members of the o...