The IHNV virus has spread worldwide and is fatal to salmon and rainbow trout – costing millions in sales of lost farmed fish. The current vaccination approach requires needle injection of fish, one by one. Now, however, Seattle-based Lumen Bioscience has come up with a new technology to make recombinant vaccines in a type of blue-green algae called Spirulina that costs pennies to produce and can be fed to fish in their feed.
To be effective, oral vaccines have not only to survive the gut environment intact but must also target the appropriate gut-associated immune cells. The approach developed by Lumen overcomes many of the problems with complex and expensive encapsulation strategies attempted in the past, according to CEO Brian Finrow.
‘[It] focuses on a new oral-vaccine platform [using] engineered Spirulina to express high amounts of target antigen in a form that is both provocative to the immune system – ie generates a desirable immune response that protects against future infection – and can be ingested orally without purification, in an organism that has been used as a safe food source for both humans and fish for decades.’
To produce the new oral vaccine, the Lumen researchers first developed a strain of Spirulina that manufactures recombinant proteins in its cell walls that the salmon immune system recognises as IHNV viruses. They then rapidly grew the strain in a large-scale indoor production system – requiring only light, water, salt and trace nutrients – and harvested and dried all the raw Spirulina biomass. This dried powder can then be fed to the fish.