According to an analysis of the Atlantic cod’s genome, scientists have discovered the fish have evolved to survive without a set of genes thought essential to the immune system. It is hoped the finding will lead to better vaccines for farmed cod and even open new avenues of medical research for human disease.

“Pathogens are a major challenge to fish farming, particularly under the dense stocking conditions that are typical of aquaculture and vaccination is a major approach to protect from diseases," said Prof Christopher Secombe, head of the Scottish Fish Immunology Research Centre. The new research will help them to target vaccine research more effectively.

The team discovered that Atlantic cod lack a set of immunity-related genes called MHC Class II, present in virtually all backboned animals. In other species, these genes contribute to the immune system's ability to recognize invading bacteria and parasites. "We could not find MHC Class II and also two other genes that are essential for protection against pathogenic bacteria and other parasites coming from the outside," said Professor Kjetill Jakobsen from the University of Oslo in Norway, who led the study.

Results published in the journal Nature could present new possibilities for the treatment of human disease. Over time, as the MHC Class II genes have been lost in cod, other genes have stepped in to compensate for the loss.

"This has some implications for medical research. I can tell you that I had a talk at the main hospital here in Oslo and there were hundreds of doctors sitting there listening to me talking about cod," said Jakobsen. "Maybe we can regulate the human immune system differently and maybe that could be treatment against certain diseases, multiple sclerosis for example," he added.

Scientists hope that the finding will also lead to improved vaccines for farmed Atlantic cod. One of the five fish species most commonly eaten in the UK, consumers spent in excess of £313.3m on cod last year.

“Pathogens are a major challenge to fish farming, particularly under the dense stocking conditions that are typical of aquaculture and vaccination is a major approach to protect from diseases."