Chula research team develops nano-vaccine option for fish

Tilapia and Asian sea bass are the economically important fish species in the market but raising them to be healthy is a painstaking task, especially when faced with the possibility of disease outbreaks such as infections from Flavobacterium commonly found in raising water environments.

The problem worsens with the over-crowding of fish in ponds and other risk factors that promotes the spread of bacteria resulting in gills disease. The disease can cause massive mortality of fish.

For this reason, 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. 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.” Channarong Rodkhum explained.
 
Why Needle-Free Vaccinations?  
When people think of vaccines, they immediately think of needles or injections. Vaccine injection in fish is, however, different from humans in terms of the process, expenses, limitations, and the risk of using needles.  

Channarong enumerated more on the process saying “We aren’t able 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 labour consumed.”  

“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.”  

Therefore, the needle–free AQUA INNOVAC is an alternative to injections with needles.  It 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.  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.”
 
Vaccine delivery via Nanotechnology 
Aside from being Thailand’s first Flavobacterium nanovaccine for fish, “FLAVO INNOVAC” is also the world’s first inactivated Flavobacterium nanovaccine against bacterial gills disease caused by Flavobacterium infection, that makes 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 the immunity of the fish continuously.  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.”

Effects of FLAVO INNOVAC tested in field research
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 vaccine is able to prevent infections at a time span of 2-3 months from the farming cycle of 6-9 months.  That may seem a rather short period, but the first trimester is when fish are rather small and highly susceptible to infections.  Boosting their immunity is, therefore, a crucial factor to ensure their survival to the next phase where they will develop greater resistance to the infections.”

Prevention of disease outbreaks is the most important task
Channarong stressed the importance of health examinations for the fish before they are released into the pond.  Administering vaccines to the fish while they are still small can also reduce losses during the early phase making it possible for them to survive until reach marketing size and can be sold to the markets.   
“Other than vaccinating the fish, another important aspect involves sending a sample group of fish to the laboratory for disease screening.  This service is available at AQUA INNOVAC Co., Ltd., Faculty of Veterinary Science as well as the Department of Fisheries. The disease screening will help determine whether the fish might have been infected prior to being vaccinated. If fish have some infections prior to being vaccinated, it can be the cause of failure for the vaccination". 

The development of FLAVO INNOVAC has received support from various sectors such as 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 another kind of vaccine for the prevention of other primary diseases which affect fish cultivation as well as other innovations which will be useful for aquatic animal health.