Researchers at the Hebrew University of Jerusalem and the University of North Carolina at Charlotte have identified what they describe as a previously unknown antiviral defense mechanism in sea anemones, an ancient animal lineage that diverged from the one leading to humans more than 600 million years ago. The work, published in Nature Ecology & Evolution, centers on a protein the team named CARDIB, which resembles the human antiviral protein MAVS but appears to function differently. The researchers say the finding suggests animal immune systems may have evolved more than one molecular strategy for combating viruses.
In humans and other vertebrates, MAVS helps activate immune responses when viruses are detected. The team initially expected CARDIB to serve a similar role in sea anemones because of its structural similarity. Instead, researchers reported that CARDIB normally suppresses antiviral defenses. Using CRISPR gene editing to remove the CARDIB gene before exposing sea anemones to viruses, the team found that animals without the gene became more vulnerable to infection, with viruses multiplying faster and the animals showing a weaker ability to mount an effective defense.
The researchers then tested whether the pathway also mattered outside laboratory conditions. Genetically modified sea anemones were transferred from aquaria to outdoor marine mesocosms supplied with natural estuarine water in South Carolina, exposing them to a broader range of viruses and microorganisms. In those conditions, sea anemones lacking CARDIB and related antiviral genes accumulated substantially more viruses than unmodified animals. The team said that result indicates the pathway is not merely a laboratory effect but plays a role in the animals' natural environment.
The study advances a broader claim about immune evolution: that similar biological challenges may have produced distinct antiviral systems in different animal groups rather than a single inherited blueprint. Researchers involved in the work argue that the results highlight the value of studying ancient organisms alongside traditional laboratory models. No direct scientific criticism or competing interpretation of the sea anemone findings was detailed, but the conclusions remain tied to this specific study and its experimental framework.