RIYADH: Scientists at King Abdullah University of Science and Technology have found that corals can be trained to better withstand disease before an outbreak occurs, a finding that could eventually help protect reefs worldwide.
The study, published in ISME Host Microbe, found that corals exposed to sublethal doses or inactive forms of a disease-causing pathogen became more resistant when they encountered the disease again.
Known as pathogen priming, the process is similar to how vaccines prepare the body to recognize and respond to future threats.
The discovery provides the first evidence that corals can develop a protective, immune memory-like response despite lacking the adaptive immune systems found in humans and other vertebrates.
Scientists have long believed that corals lacked the biological machinery needed to “remember” disease threats. The new findings suggest they may be more sophisticated than previously thought, opening a new avenue of research into how reef-building corals defend themselves against infection.
“Coral disease is becoming an increasingly important challenge for reefs worldwide,” said Raquel Peixoto, professor of marine science at KAUST and senior author of the study.
“What surprised us was finding that corals exposed to a pathogen were significantly better able to respond when they encountered the same disease agent again. It suggests corals can be trained to strengthen their natural defenses, something that had not been demonstrated before,” Peixoto added.
The findings come as coral reefs face increasing pressure from warming oceans and other environmental stressors. Disease outbreaks can spread quickly across reefs and coral nurseries, resulting in significant losses and hindering restoration efforts.
Researchers believe the discovery could eventually offer a new tool for coral conservation. By preparing corals before they encounter disease, pathogen priming could help increase survival rates in nurseries, restoration programs and other high-value reef environments.
“Most people don’t think of corals as animals that can learn from previous disease exposure,” said Matteo Monti, a postdoctoral fellow at KAUST and lead author of the study. “Yet that is exactly what we observed.”
Monti added: “This is not a vaccine in the way we think about human medicine, but the principle is similar. The most exciting part of this work is that it raises entirely new questions. If corals can develop this kind of protection, we now need to understand how widespread it is, how long it lasts and whether it can be used to support conservation efforts in the future.”
The research also found that the protective effect is linked not only to changes within the coral itself but also to changes in its microbiome, the community of microorganisms that live alongside corals and support their health.
The discovery builds on KAUST’s broader research into coral resilience and reef restoration. While earlier studies have explored beneficial microbes, or probiotics, as a way to support coral health, pathogen priming turns the microbial “dark side” into an ally by using weakened or inactive disease-causing microbes to train corals to recognize and resist future infections.
The team has filed a patent application for the use of pathogen priming to strengthen coral disease resistance and is now testing the approach across additional coral species, pathogens and environmental conditions. If successful, the technique could eventually give coral nurseries and restoration programs a new tool to help protect reefs before disease outbreaks occur.
