Fisheries will soon reach the maximum capacity in global food
production. Consequently, food from aquaculture will be more important
for future food security.
The intensive farming of fin fishes and shellfishes has led to an
imbalance of optimal culture conditions, which shows increased
susceptibility to infectious disease.
Under these conditions, the prevalence and spread of infectious diseases
will unavoidably increase due to higher infection pressure and
deterioration of environmental conditions, so good husbandry practices
and health management must be emphasized.
Use of antibiotics has attracted lot of criticism due to the issues like
antibiotic residues, bacterial drug resistance and toxicity.
In this present scenario, vaccination would be the best alternative to
combat bacterial and viral disease for the sustainable aquaculture.
The first report on fish vaccination was done by David C. B. Duff
and he is regarded as "Father of fish vaccination”.
The vaccines against Fish infectious bacterial diseases were
developed in 1970s, It is commercialized in 1980s.
Later due to the reduced environmental impact and improved food
quality obtained by minimizing antibiotic use in addition, animal
welfare has been improved by the implementation of vaccination.
A vaccine is a biological preparation that improves
immunity to a particular disease. A vaccine typically
contains an agent that resembles a disease-causing
microorganism, and is often made from weakened or
killed forms the microbe. The agent stimulates the
body's immune system to recognize the agent as
foreign, destroy it, and "remember" it, so that the
immune system can more easily recognize and
destroy any of these microorganisms that it later
encounters in future.
Concept of vaccination
"Prevention is better than cure”
• Vaccination is an easy, effective and preventive method of protecting
fish from diseases. Vaccination is a process by which a protective
immune response is induced in an animal by administration of vaccines.
• Once fish stimulated by a vaccine, the antibody-producing cells, called
B lymphocytes, remain sensitized and ready to respond to the agent
should it ever gain entry to the body.
TYPES OF VACCINES
On the basis of inducing agent and preparation method Vaccines are can be
• Purified Macromolecules as Vaccines
• Recombinant vaccine
• DNA vaccine
Killed or Inactivated: these vaccines contains killed, but previously
virulent, micro-organisms that have been destroyed with chemicals, heat,
radioactivity or antibiotics.
Effective, but not Infective
Attenuated: these vaccines contains live, attenuated microorganisms.
Many of these are live microorganisms that have been cultivated under
conditions that disable their virulent properties or which use closely related but
less dangerous organisms to produce a broad immune response.
• A vaccine for
Koi Herpes Virus (KHV) based
on attenuated Carp, Interstitial
Nephritis and Gill Necrosis Virus .
Inactivated exotoxins or Toxoid
Toxoids are vaccines which consist of exotoxins that have been
inactivated, either by heat or chemicals. These vaccines are intended to
build immunity against the toxins.
Subunit vaccines are made from a small portion of a micro-
organism (rather than the entire micro-organism) that ideally will
stimulate an immune response to the entire organism.
Example: IPN-vaccine for salmonid fish
Certain bacteria have polysaccharide outer coats that are
poorly immunogenic. By linking these outer coats to proteins,
the immune system can be led to recognize the polysaccharide.
o Recombinant vaccines are produced by using
o Identfy and isolate specific gene from bacteria
o Gene is inserted into plasmid DNA and ligated.
This engineered plasmid transformed into another
o Allow the bacterial culture to grow and produce
the antigenic protein.
o The vaccine is purified protein recovered from
bacteria or virus.
When the genes for a microbe’s antigens are introduced into the body, some
cells will take up that DNA. The DNA then instructs those cells to make the
antigen molecules. The cells secrete the antigens and display them on their
surfaces. In other words, the body’s own cells become vaccine-making
factories, creating the antigens necessary to stimulate the immune system.
Development of Fish Vaccines
Aetiology of Disease
Characterization of Isolates
Definition of Disease
Lab Vaccination Tests
Normally 5 – 8
years in R&D
Epidemiology and disease
Field and licensing
SELECTING THE STRAINS FOR
GROWING THE MICRO-
ISOLATION & PURIFICATION OF
INACTIVATION OF ORGANISM
FORMULATION OF VACCINE
QUALITY CONTROLAND LOT RELEASE
SELECTING THE STRAINS FOR VACCINE PRODUCTION
• The Seed(Strain) -
– Manufacturing begins with small amounts of a specific bacteria or virus
called as seed.
GROWING THE MICROORGANISMS
• GROWING BACTERIA
Methods used are :
– BATCH CULTURE
– CONTINUOUS CULTURE
• GROWING VIRUSES
– Methods used are :
• CELL (TISSUE) CULTURES
• BIRD EMBRYOS
• LIVE ANIMAL INOCULATION
Isolation & Purification of microorganism
• Product isolation is the removal of those components whose properties vary
markedly from that of the desired product.
• Purification selectively separates and retains the desired product at the highest
purity as per its pre-determined specification.(Remove unwanted compounds).
Differential Centrifugation –
Density gradient Centrifugation –
Ion exchange chromatography:-
Affinity chromatography :-
Inactivation of microorganism
Virus inactivation involves dismantling a virus’s ability to infect cells
without actually eliminating the virus.
1- By attacking the viral envelope or capsid and destroying its ability to
infect or interact with cells.
2- By disrupting the viral DNA or RNA and preventing replication.
• Solvent/detergent (S/D) inactivation
• Acidic pH inactivation(Low pH Treatment)
• Ultraviolet (UV) inactivation
QUALITY CONTROL AND LOT RELEASE
Prior to release the manufacturer must test-
PURITY, SAFETY, AND POTENCY TESTS-
VIRULENCE TESTS – All live vaccines should be tested for virulence
ASSESSING RISK TO THE ENVIRONMENT –
CONSISTENCY OF PRODUCTION –
• PERFORMANCE MONITORING
• Injection delivery system is an effective way of inducing antibody response in
fish. The injection may be intraperitoneal or intramuscular.
• Injection is in general superior to any other vaccine application method because
it is directly incorporate vaccine in the body.But main disadvantage is it may
cause stress and inflammatory reactions.
(a) Dip vaccination
(b) Bath vaccination
• In dip vaccination, fish are immersed for a short duration, usually 30-60 sec, in
a highly concentrated vaccine solution.
• In bath vaccination, fish are exposed for a longer time, usually one to several
hrs, in a lower concentration of antigen.
• Immersion vaccination is widely used for fry. It is an effective method that
results in relatively good protection for a significant period of time.
• In oral vaccination, the vaccine is either mixed with the feed,
coated on top of the feed (top dressed) or bio-encapsulated .
• Bio-encapsulation is used where fish or shrimp fry are to be
vaccinated. In this case, live feed such as Artemia nauplii,
copepods or rotifers are incubated in a vaccine suspension and
then fed to the fry.
• Since these live organisms are non-selective filter feeders, they
will accumulate the antigen in their digestive tract and, as such,
transform themselves into living microcapsules .
• Recently biofilm of bacterial pathogen has been evolved
successfully for oral vaccination of fish with high antibody tire
and protection. The glycocalyx of biofilm helps to resist the
vaccine destruction in the foregut favouring better antigen
delivery to immune responsive sites in the hind gut.
• Oral vaccination has the advantage in that it is easy to administer
and causes no stress to the fish.
VACCINES SPECIES DISEASE
Aeromonas salmonicida Bacterin Atlantic salmon Furunculosis
Vibrio anguillarum. V. Ordalii Bacterin Rainbow trout Vibriosis,
Yersinia ruckeri Bacterin Salmonids Yersiniosis (enteric red-
Vibrio salmonicida Bacterin Salmonids Vibriosis
Vibrio anguillarum-salmonicida Bacterin Salmonids Vibriosis
Aeromonas salmonicida Bacterin Salmonids Furunculosis
Edwardsiella ictaluri Bacterin Catfish Enteric septicaemia
Spring viraemia of carp virus Common carp Spring viraemia of carp
Koi herpes virus (KHV) Koi carp Koi herpes virus (KHV)
Biofilm and free-cell vaccines of
Indian major carps Dropsy
Streptococcus agalactiae vaccine Tilapia Streptococcosis
Betanodavirus Grouper Betanodavirus disease
• within the genus Vibrio, the species causing the most
economically serious diseases in marine culture are Vibrio
anguillarum, V.ordalii, V.salmonicida and V.vulnificus.
• Number of commercial Vibrio anguillarum vaccines have been
developed for use mainly by injection.
Winter Ulcer is a disease
affecting sea-farmed atlantic
Today Moritella viscosa has
been incorporated in the Oil-
based mutivalent vaccines
employed routienly in the
salmon industry of the
Pasteurellosis currently described
also as photobacteriods, is caused
by the halophilic bacterium
Which causes economic losses in
the marine culture of
yellotail(Seriola quinquerdiata) in
In recent year, several
commercial vaccines against
P.damselae have been made
available on the market, their
efficacy is dependent on fish
species, fish size, vaccine
o Aeromonas salmlonicida is the causative agent which causes
economically devastating losses in cultivated salmonids in fresh
water and marine waters.
o Many furunculosis bacterins have been developed and
commercialized since 1980 to be used in salmonids by injection,
immersion or the oral route.
o Yersinia ruckeri is the causal
agent of yersiniosis or enteric
red mouth (ERM) disease.
o commercial ERM vaccines
have been extensively used for
decades. the formalin-killed
whole-cell vaccine continues to
be highly effective whether
administered by immersion,
spray, injection or oral routes.
Enteric septicaemia of cat
fish, ESC (Edwardsiella
Edwardsiella ictaluri is the
enterobacterium responsible for
enteric septicemia of catfish,
with channel cat fish being the
most susceptible fish species
among them to E. ictaluri .
Recently an attenuated O-
antigen deficient E.ictaluri strain
has been developed which was
safe and provided high long
lasting acquired immunity with
immersion in 9-14 day old
Cold water disease or
rainbow trout fry
psychrophilum has been
known as the causative
agent of bacterial cold water
• Recent vaccination
experiment performed with
young rainbow trout
significant protection was
achieved using oil-adjuvant
(Intra peritoneal) vaccines.
(red spot disease)
o The Pseudo monas species
recovered from disease fish.
is considered the significant
pathogens for cultured fish.
o In recent research efforts
production of aqueous and
non-mineral oil- adjuvanted
bacterins with proved to be
effective in experiment
trials in gilt head sea bream
o BKD caused by the gram-
is a chronic systemic disease of
salmonids which causes
mortality in cultured fish in
fresh and marine environment.
o Recently a commercial
aqueous live vaccine
developed by Novartis S.A has
been licensed under the name
of ‘Renogen’ for BKD
• Inactivated vaccines are used against infectious pancreatic
necrosis (IPN), infectious salmon anaemia (ISA) and pancreas
disease (PD) .
• A DNA vaccine against infectious haematopoietic necrosis (IHN)
is produced in in Canada. The vaccine gives acceptable protection.
• Research on DNA-vaccines for several diseases (IPN, VHS, koi
herpes virus-infection, spring viraemia in carp)
Potential benefits of vaccines
Increased appetite and growth in vaccinated fish compared to non-
vaccinated fish is more because of the better food conversion rates in
Potential of growing vaccinated fish at higher densities because disease
is not a limiting factor in the population.
Immunization of pre-spawning females may have potential as a means of
protecting fish against pathogens which affect the early life stages , such
as Flavabacterium psychrophilum, Edwardisiella ictaluri.
Reduction of drug use and therefore, the no appearance of bacterial
drug resistance, as well as drug residues in the final product.
Improvement of industry image for the sanitary quality of the fish
produced, as well as from the environmental safety stand point of view.
As part of health management measures, vaccination can be
effective for disease control in future.
To achieve progress in fish vaccinology, an increase in the co-
operation between basic and applied science (i.e., between the
Immunologist, microbiologist and the vaccinologist ) is needed.
Early identification and characterization etiology and epidemiology
of the diseases of causing agent.
Identification of the earliest time to vaccinate and available
windows for vaccination (i.e. ontogeny of the immune system) .
Development of new non-mineral oil adjuvants lacking side
Development of polyvalent vaccines and standardization of a
vaccination calendar appropriate for each economically
important fish species.
Improvement in oral immunity with biodegradable
microparticle based vaccines to be used for booster
Investigation of the mechanisms of immunoglobulin transfer
from pre-spawning females to offspring as a useful way of
protecting fish against pathogens which affect early life stages.
The primary risk associated with vaccines, especially vaccines that utilize
live organisms and vaccine itself may causes illness.
Vaccine may behave as a super antigen and over stimulate the immune
Some individuals may have an allergic reaction to the vaccine.
poor delivery technique may cause stresses which can result tissue
damage, necrosis, infection or internal organ damage and death.
Decrease in growth caused by side effects such as those produced by
some adjuvant vaccines.
Fish are weakened by improper handling or rearing practices.
Aquaculture continues to expand, disease problems will increase.
Therefore, disease research and the implementation of new disease
control concepts are important to maintain sustainability.
The development of an effective vaccine is a complex process. One of
the prerequisites understanding of basic epidemiology of diseases and
the immune system of the target species is required.
The importance of disease control is increasingly recognized by both
farmers and governments due to the significant economic losses caused
by diseases and international pressure on the use of chemicals and
A number of vaccines have been in used by the salmonid industry
for decades, however, commercial vaccine development for other
aquaculture sectors, including warm water fish, is still quite limited.
Currently, vaccines are available for some economically important
bacterial and viral diseases but vaccines for protection against
parasitic and fungal diseases have not yet been developed.
For the future of the fish farming industry it is also important that
vaccination contributes to a sustainable biological production with
negligible consumption of antibiotics.
Thus, increased resources have been allocated for disease research.
In turn, to improved information on diagnostic techniques,
infectious diseases and standardization of the culture practices will
assist the development of vaccines in the future.
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