A severe ISAV outbreak plunged the Chilean salmon industry into crisis in 2007. With mortality rates up to 90% across hundreds of farms, 60% of operations halted production. This led to widespread layoffs and losses, directly and indirectly affecting more than 100,000 people.
Chile currently stands as the world's second-largest salmon producer, behind Norway, with a record 1,090,000 net tons across Atlantic salmon, Pacific salmon, and rainbow trout in 2023. This strategically important industry, concentrated in the country's southern regions, faces significant health challenges. Viral diseases, in particular, pose a major threat to fish health and the sector's sustainability.
Dr. Marcelo Cortez, a professor at the University of Santiago, Chile's Faculty of Chemistry and Biology since late 2008, began researching the ISAV virus after the 2007 health crisis. This research has since solidified into Fondecyt Regular project #1251842, specifically designed to unravel the genetic mechanisms behind the virus's aggressiveness, forecast the behavior of emerging variants, and provide crucial insights for enhanced vaccines and diagnostic tools.
Utilizing a reverse genetics system, the project designs modified virus versions in the laboratory. Researchers precisely alter genetic material fragments and introduce them into cells, which then produce new viruses with desired characteristics for study. This method is crucial for observing how specific genetic changes impact the virus's behavior, such as its infectivity, replication rate, or ability to evade the immune response.
"The infectious salmon anemia virus belongs to the same family as the human influenza virus, the Orthomyxoviruses, and just as the influenza virus can cause pandemics in humans, ISAV in Chile behaved in a very similar way, causing a local epidemic with extremely high mortality rates and affecting a huge number of fish in a short period of time. In this project, we aim to study from a molecular perspective the virulence markers, especially the fusion protein, that make one virus more aggressive than another within the viral species.
Virulence markers are genetic changes or mutations in the virus's genome that alter its protein characteristics. These alterations can enhance the virus's ability to spread, increase its disease-causing potential, or enable it to evade vaccine-induced immune responses. Understanding these "genetic keys" is crucial for anticipating viral behavior during outbreaks and developing more effective control tools.
"Studying these factors allows us to project the behavior of a new viral variant before it causes an outbreak," explains Dr. Marcelo Cortez. "It's about staying ahead of the curve, preparing better with diagnostics and vaccine development. We can identify future mutations to watch for, and even design vaccines that protect against variants that don't yet exist. That's one of the great contributions this research can make from the laboratory."
This project extends beyond direct ISAV virus research, serving as a strategic opportunity to enhance Chile's virology capabilities. It promotes multidisciplinary approaches, evidenced by collaboration with co-investigators Dr. Yesseny Vásquez (Usach School of Medicine) and Dr. Margarita Montoya (Department of Biology). Ultimately, the lab's work generates knowledge, trains researchers, develops specialized techniques, and solidifies scientific infrastructure.
"Virology is a poorly established discipline in Chile," concludes the Usach researcher. "Very few of us are dedicated to this field, and we lack the necessary infrastructure for growth. There are no specialized conferences, highlighting the urgent need for Chile to strengthen virology – not just to face future health crises, but also to position itself as a serious player in science and biotechnology."