New immersive nanovaccine tackles Flavobacterium diseases in fish without injection

Researchers from the Faculty of Veterinary Science at Chulalongkorn University in Thailand have developed a nanovaccine to prevent bacterial gill diseases in freshwater fish species such as Tilapia and freshwater Asian sea bass.

This FLAVO INNOVAC nanovaccine is an effective solution that reduces the risk of death from diseases and the limitations of vaccine injections.

Tilapia and Asian sea bass are economically important fish species but raising them can be affected by disease outbreaks such as infections from Flavobacterium, a problem which worsens with the over-crowding of fish in ponds and other risk factors and which can cause massive mortality of fish.

Associate Professor Dr Channarong Rodkhum has formed a collaborative effort with a research team from the Center of Excellence in Fish Infectious Diseases (CE FID) and Aqua Innovac Co. Ltd. to develop FLAVO INNOVAC, the world’s first inactivated Flavobacterium nanovaccine.                                      

“Normally fish farming or aquatic industries do experience diseases and infections. Overcrowding, bad environments and water quality, increase of organic substances, or changes in water temperatures can weaken the fish making them susceptible to diseases,” he said. 

”Flavobacterium spp. is the causative agent that attacks fish and causes gills and skin infections leading to as high as up to 100% mortality rates, especially among the juvenile stage of fish that are still weak and cannot specifically protect themselves from Flavobacterium spp. infections. This can be prevented by administering a vaccine for these fish.” 

Dr Channarong said it isn’t possible to inject a fish directly as it will start moving which causes fish stress.

”Injecting a fish means, therefore, that the fish first needs to be made unconscious by way of soaking it in a sedative agent for a while - after that fish will be injected one by one by an expert.  The process also involves transferring the vaccinated fish into the pond.  All of this increases the costs and labor consumed,” he said.

“Vaccine injection in fish also involves the risk of infections at injection sites.  Another limitation is that we are unable to inject very small fish.”  

Instead, the needle–free AQUA INNOVAC can effectively stimulate the specific immune responses of the fish at a lower cost and enable vaccination of a mass population of fish at one time, up to many thousands or millions.   

“Fish farmers can prepare FLAVO INNOVAC vaccination easily by themselves. The fish need to be immersed in water mixed with the vaccine for approximately 20-30 min in the proportions determined on the labels.  During that time, the fish need to be given oxygen for the entire time,” Dr Channarong said.  

”After receiving the vaccine, the fish can be released into the ponds right away.  The nano vaccine is produced from the strain of Flavobacterium spp. locally isolated here in Thailand and is therefore very effective in the prevention of diseases occurred by a local strain of Flavobacterium spp.”                          

FLAVO INNOVAC is the world’s first inactivated Flavobacterium nanovaccine against bacterial gill disease caused by Flavobacterium infection to make use of nanotechnology for its delivery.

“Nanotechnology helps encapsulate the vaccine antigens.  When the fish is soaked in the nanovaccine which has positive charge, the vaccine can attach itself to the negative charge of fish mucous membranes.  The organic nanoparticles will then release antigens that help stimulate immunity of the fish continuously,” Dr Channarong said.  

”Once those antigens have all been released the organic nanoparticles will gradually decompose within a short time, and without leaving the residues.  This makes it safe for the fish, the environment and also the consumers.”

FLAVO INNOVAC is currently undergoing field clinical trials along with the assessment of marketing results.  Reactions from those farmers who have experienced the project have been largely positive.  

The development of FLAVO INNOVAC has been supported by Chulalongkorn University, the National Research Council of Thailand (NRCT), Thailand Science Research and Innovation (TSRI), as well as the Chulalongkorn University Technology Center (CU UTC) for the spinoff company’s incubation.  The research team plans to develop a booster vaccine that can be mixed with fish feed that will be easier and more convenient to administer.   

Aside from the FLAVO INNOVAC vaccine innovation, AQUA INNOVAC Co. Ltd. also plans to develop other kind of vaccines for prevention of other primary diseases which effect to fish cultivation as well as other innovations which will be useful for aquatic animal health.