In an experiment conducted earlier this year, SDSU biology professor Forest Rohwer and post-doctoral researcher Rebecca Vega Thurber found that the more "stressed" coral was, the more likely the herpes virus was to replicate. The finding is particularly important because past research focused mostly on fungal and bacterial infections and nothing was known about viruses in corals.
"When you take healthy coral, there’s a low abundance of herpes," said Vega Thurber. "Our experiments show that coral infections are similar to people with herpes – viral replication increases under stress."
Vega Thurber and Rohwer created stressed conditions by creating a more acidic environment, increasing nutrients and temperatures. They chose these particular stressors because they replicate actual conditions threatening coral reefs worldwide.
Recent research shows that 20 percent of the world’s coral reefs have been destroyed and show no prospects of recovery. Another 50 percent of the world’s coral reefs face the threat of collapse now or in the future.
While the herpes virus was rarely found in healthy coral, it was found in abundance in many of the experiment’s stressed samples. However it is still unknown as to how the virus affects coral. Besides creating lesions, researchers would like to know if there are other negative effects such as tumor formation.
"There's no active immune system in coral; however, they have innate immunity," said Vega Thurber. "So, it's unclear how coral are affected by a herpes infection or how they fight it off."
Rohwer and Vega Thurber plan to continue their research by investigating how coral are affected by the viral infection. Additionally, they hope that their findings will lead to research into the evolution of the herpes virus.
"Herpes viruses always infect nervous tissue," Vega Thurber said. "Since Cnidarians, the group of animals to which corals belong, were the first to develop nervous systems, other researchers may be able to trace the evolution of the herpes virus and how it has changed over time."
The article is published online and in the Nov. 10 print version of the Proceedings of the National Academy of Sciences journal.
San Diego State University researchers have discovered that ancient herpes-like viruses infect stressed coral.