New grant will help develop vaccine delivery system for tilapia lake virus

The Foundation for Food and Agriculture Research (FFAR) has joined in the war against the tilapia lake virus (TLV) with a USD 790,326 (EUR 671,206) Seeding Solutions grant award to the University of Florida in support of development of a vaccine delivery system for halting spread of the disease. Curtiss Healthcare has also provided matching funds bring the total investment to USD 1,830,312 (EUR 1,554,444).

FFAR said although TLV has yet to be reported in North America, there is a risk that if it arrived it could pose harmful consequences – exacerbating mortality rates in fish farms which have already climbed to an all-time high of 50 percent or more.

“We are proud to fund this bold research that seeks to develop a vaccine that will reduce mortality in fisheries, preserve food stocks, and boost farmer profitability,” FFAR Executive Director Sally Rockey said.

Previously, FAO estimated tilapines globally to comprise 700 species – making it the second-most important group of farmed fish after fish after carp. FFAR said tilapia generates up to USD 244 billion (EUR 207 billion) annually for the global economy. But TLV has remained a major threat to the global aquaculture industry, with the World Organisation for Animal Health (OIE) pointing out the that the disease could cause mortality could go up to 90 percent.

With no vaccine or drug available for treatment of the TLV, OIE has proposed restrictions on the movement of live tilapines from farms and fisheries where incidents of the disease have been reported, along with the use of generic biosecurity measures such as cleaning and disinfection to minimize fomite spread through equipment, vehicles, or people.

Although there has been no thorough investigation of all mortality incidents in many tilapia-farming countries in Africa, TLV has previously been reported in Colombia, Ecuador, Israel, Egypt, Thailand, Malaysia, and the Philippines.

In Africa, tilapia mortality in Ghana, Rwanda, and Zambia has been reported, but there has been no official confirmation on the cause of the fish deaths.

Many years after OIE recommended tilapia breeding for resistance to TLV or the development of a vaccine as a lasting solution, the University of Florida said with the FFAR and Curtiss Healthcare grant it is now possible to develop an innovative DNA vaccine delivery system.

The university’s researchers, led by Roy Curtiss, will base the vaccine delivery system on “weakened and programmed self-destructing bacterial strains, which can be applied through the mucous membranes and enable complete protection against the virus.”

“Mucosal delivery is cost-effective and stimulates all branches of the immune system,” FFAR said.

The vaccine is expected to boost productivity of tilapia farming and “the platform technology could be used for other aquaculture pathogens, enhancing sustainable agriculture.” 

“The vaccine delivery system being developed for fish is patterned after the salmonella-vectored vaccines our lab has created for preventing infectious diseases in farm animals, as well as enhancing food safety by decreasing the threat of pathogens transmitted from animals to humans through the food chain,” Curtiss said. “These vaccines are also to likely reduce use of antibiotics in agriculture and thus reduce selection for drug-resistant bacterial pathogens.”  

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