RECENT DEVELOPMENTS IN VACCINATION IN FISH

1. RECENT
DEVELOPMENTS IN
VACCINATION IN
FISH
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• Mr. MAHIDA PARVEZ JILANI
• Department of Aquaculture

2. BACKGROUND - AQACULTURE
• Agriculture and fisheries will soon reach the maximum
capacity in global food production
• Consequently, food from aquaculture will be more
important for future food security. Aquaculture must be
sustainable with minimal use of antibiotics and chemicals
• Correct use of vaccines will contribute to sustainability in
aquaculture
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3. BACK GROUND - VACCINE
 The first vaccines for aquaculture were simple
products like formalin inactivated bacterial cultures
 Most modern fish vaccines are research based products
 The way from research to licensed vaccines is long and
expensive
 A licensed vaccine may be required for import of
aquaculture products Many countries (EU-countries
and USA) and organizations (FAO, OIE, WTO) have
strict import requirements related to the use of vaccines
in aquaculture production
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4. 03/05/15 4
• The first vaccines against Fish infectious bacterial
diseases were developed in 1970.
• It is commercial in 1980.
• This has contributed significantly to the growth of
the industry to consumer acceptance of farm raised.
• Research over many year very few Anti-viral
vaccines are available.
• There are no commercial vaccines against parasite.

5. HISTORY OF VACCINES
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6. 03/05/15 6
Aquaculture Vaccines - History
• Furunculosis - Proof of concept - Duff (1942)
• Commercial bacterial vaccines (mid 1970’s)
• Oil adjuvanted injectable vaccines (early 1990’s)
• Commercial viral vaccines (mid 1990’s)
• Commercial recombinant vaccines (late 1990’s)
• Commercial DNA vaccine (2005)
• Reverse engineered & multiepitope vaccines
(2007)

7. Edward Jenner (1749-1823)
• Edward Jenner, for the
first time in 1796 used
cow pox vaccine against
the small pox
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8. Louis Pasteur (1822-1895)
• Introduced the term‘virus-
vaccin’ synonymous with
attenuated microbe
• Germ theory of disease
rabies vaccine in 1885
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9. From Louis Pasteur to fish
vaccinology
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10. vaccines
• “Vaccines are preparations of antigens derived
from pathogenic organisms, rendered non-
pathogenic by various means, which will
stimulate the immune system in such a way as to
increase the resistance to disease from subsequent
infection by a pathogen.”
A.E. Ellis, 1988
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11. The concept of vaccination
Vaccination
Pathogens (bacteria, viruses…⃝
Resistance to
infection
Mortality
Treatment
Healthy
Infection
Diseased
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12. Principle of vaccination
• The major principle of vaccination is memory
and specificity”
• Immunological Memory: The ability of the
immune system, upon interaction with a
previously encountered antigen produce a
stronger and faster immune response
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13. Specificity
• The exquisite specificity of the immune
system allows it to selectively recognize
billions of different foreign antigens, while
maintaining tolerance to an equally diverse
panel of self antigens
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14. Development of Fish VaccinesDevelopment of Fish VaccinesDevelopment of Fish VaccinesDevelopment of Fish Vaccines
Disease InformationDisease InformationDisease InformationDisease Information
A etiology of DiseaseA etiology of DiseaseA etiology of DiseaseA etiology of Disease
Characterization of IsolatesCharacterization of IsolatesCharacterization of IsolatesCharacterization of Isolates
Definition of DiseaseDefinition of DiseaseDefinition of DiseaseDefinition of Disease
Challenge Model Devel.Challenge Model Devel.Challenge Model Devel.Challenge Model Devel.
Vaccine DevelopmentVaccine DevelopmentVaccine DevelopmentVaccine Development
Vaccine ProductionVaccine ProductionVaccine ProductionVaccine Production
Lab Vaccination TestsLab Vaccination TestsLab Vaccination TestsLab Vaccination Tests
Pre-Licensing StudiesPre-Licensing StudiesPre-Licensing StudiesPre-Licensing Studies
LicensingLicensingLicensingLicensing
Marketing PreparationMarketing PreparationMarketing PreparationMarketing Preparation
Product IntroductionProduct IntroductionProduct IntroductionProduct Introduction
Normally 5 – 8Normally 5 – 8
years in R&Dyears in R&D
Normally 5 – 8Normally 5 – 8
years in R&Dyears in R&D
Epidemiology and diseaseEpidemiology and disease
investigationinvestigation
Laboratory phaseLaboratory phase
Field and licencingField and licencing
phasephase
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15. Important considerations for fish
vaccination
• Species
• Status of the immune system
• Production cycle and life history
• What diseases do you want to control?
• When do these diseases occur?
• Farming technology (Handling, mechanization)
• Environment (temperature, salinity)
• Stress factors, nutrition and cost benefit
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16. Globally Important Bacterial
Pathogens in Aquaculture
• Listonella
• Vibrio anguillarum
• Aeromonas salmonicida
• Yersinia ruckeri
• Renibacterium salmonarium
• Lactococcus/Streptococcus sp
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17. Globally Important Viral Pathogens in
Aquaculture
Infectious Pancreatic Necrosis (IPN)
Salmon Pancreas Disease (SPD)
Sleeping Disease of Trout (SD)
Infectious Salmon Anaemia(ISA)
Viral Nervous Necrosis (VNN)
Infectious Haematopoietic Necrosis (IHN)
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18. The Ideal characteristics of Fish
Vaccine ?
• Sustained immunity and protection
• Early mass application
• Efficacious for a broad number of species
• Safe
• Cheap and cost effective
• Easily produced
• Stable
• Will not interfere with diagnosis
• Easily licensed
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19. What Fish vaccines are Used?
• Most commonly used antigens in fish vaccines to
date are inactivated or killed bacterial and viral
• Most successful use has been against
Furunculosis (Aeromonas salmonicida) in salmon
• Several inactivated antigens now present in
most commonly used salmon vaccines, i.e.
multivalent
• Recombinant sub unit vaccine used for IPN
• DNA vaccines for IHN and VHS in development
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20. • Immune system of fish Similarities and
differences compared with warm blooded animals
• Innate immunity is more important in fish
Specific immunity is less developed in fish
• Maternal immunity cannot be used for disease
prevention in fish
• Protective immunity can be developed even in
young fish
• Salmonid fish at a size of less than 5 grams
develop immunity Variation between fish species
• Salmonid fish differ from cod fish
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21. 03/05/15 21
TYPES OF VACCINES
1) INACTIVATED VACCINES
•Most bacterial vaccines used in aquaculture to date have
been inactivated vaccines obtained from broth culture of a
specific strain(s) subjected to subsequent formalin
inactivation.
•The best results are obtained with those bacterins that
include both bacterins cells and extracellular products.

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• Whereas with some vaccines acceptable levels
of protection are achieved with aqueous
formulation administered by injection or
immersion.
• Bacterins such as those devised for Salmonids
against Aeromonas salmonicidia an
accepatable level of protection can only be
achieved by immuunization with oil –
adjuvanted bacterins delivered by injection.

23. 2) LIVE VACCINES
 These should have many advantages in Aquaculture.
 Live vaccines also have the advantage that stimulate the
cellular branch of the immune system.
 Some live vaccines have been tested experimentally are
Aermonas salmonicida, Edwardiella tarda E.ictaluri.
 At present ,only on E.ictaluri attenuated live vaccine has
licensed in then USA to be used by both in 9-days old
fish to prevent ESC of cat fish.

24. Cont…
3) DNA vaccines
•DNA vaccines have theoretical advantage over conventional
vaccines in mammals the specific immune response after
DNA vaccination encompasses antibodies ,T-helper cells and
cytotoxic cells.
•As the DNA sequence encodes only a single microbial gene ,
there should be no possibility of reversion to virulence.
•It is a critical factor to factor in enviromental saftey in
Aquaculture.

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4) BIOFILM VACCINES
Bacterial biofilm is a colony of high density of cell
embedded in a glycocalyx matrix on a substrate, which has
been demonstrated to be resistant to action of antibiotics
chemicals and host immune system. Bacteria biofilm on
suitable substrate after inactivation can be used as a
successful oral vaccine.
5) RECOMBINANT PROTEIN VACCINES
It starts with identification of immunogenic subunit or
protein from a pathogen of interest followed by the genes
involved in coding for them which can be introduced into
a vector, over expressed in expression hosts and can be
used as recombinant protein vaccines .

26. Adjuvants - a challenge
• Adjuvants are necessary in order to achieve
acceptable protection against some diseases
• Oil adjuvants may cause adherence in peritoneal
cavity and muscle pigmentation
• The side effects caused by some adjuvants are
not acceptable from an animal welfare point of
view
• The search for improved adjuvants and factors
contributing to the side effects is a great
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27. VACCINATION METHODS
Direct immersion
Oral
Injection

28. Vaccination Methods
Injection vaccination
–Intraperitoneal (adjuvant or not)
–Intramuscular (DNA )
Immersion vaccination
–Bath method
–Dip method
–Spray vaccination
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29. Vaccination Methods
Spray vaccination:
A variant of immersion could be used
in larger fish where injection not possible
Oral vaccination:
Micro-encapsulation method
Bio-encapsulation method
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30. Fish vaccination process
• Fish are transported in pipes from the
rearing tanks to an anesthetic bath.
• The anaesthetized fish are injected by the
vaccination team.
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31. Injection vaccination -by hand
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32. Injection by machine
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33. Fish immersion vaccination
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34. Oral vaccination
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35. Advantages & disadvantages of
immersion vaccination
Suitable for mass vaccination of all sizes of fish
 Reduced stress for fish
 Lower labour costs
 Less risk to vaccination team
• Major disadvantages are the large amount of
vaccine required and lower level of protection
and duration of immunity
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36. Advantages & disadvantages of
Injection vaccination
• Most common method of vaccine delivery in fish
• Highly efficient in generating both humoral (antibody)
and cellular cytotoxic response
• Disadvantages :
 Unsuitable for small fish
 Needs sophisticated machinery or large skilled
workforce
 Significant handling stress and risk of post
vaccination fungal infections
 Local reactions
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37. Advantages & disadvantages of
Oral vaccination
 Vaccine mixed with feed
 Easiest method for mass vaccination of all sizes
of fish
 Saves labour and avoids stress
• Disadvantages :
Large quantities of antigen required
 Requires all fish to be feeding
 Protection generally weak and of short duration
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38. Choice of Application method
Determined by
 Vaccination window
 Size of fish
 Duration of protection required
 Type of pathogen
 Type of immune reaction
 Single versus multivalent product
 Cost of vaccine
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39. The ideal vaccination strategy
• Oral vaccines of high efficacy which could be given
in or on the food as required given required
• Immersion vaccine injection oral boosters as
required
• Currently salmonid industry relies on a single
industry injection of a multivalent vaccine
• Danger of antigen overload
• New vaccines and vaccine strategy required
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40. Successful vaccination of fish
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41. Successful vaccination against bacterial
diseases
• Atlantic salmon and rainbow vibriosis trout are
vaccinated against:
• vibriosis (Vibrio anguillarum)
• cold water vibriosis (Vibrio salmonicida),
• Furunculosis (Aeromonas salmonicida) prior to sea
transfer with an injectable adjuvanted vaccine
(SOURCE : Håstein et al. 2005 Dev.Biol 121, 55-74)
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42. Viral vaccines
Inactivated vaccines are used against infectious
pancreatic necrosis (IPN), infectious salmon anaemia
(ISA) and pancreas disease (PD) with some effect
A DNA vaccine against infectious haematopoietic
necrosis (IHN) is licenced in Canada.
The vaccine gives acceptable protection…….
Research on DNA-vaccines for several diseases
(IPN,VHS, koi herpes virus-infection, spring viraemia in
carp)
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43. New technologies
• Sub-unit vaccines
• Deletion mutants
• Live vectored vaccines
• DNA-vaccines
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44. Subunit vaccines
• Subunit vaccines contain a portion of the
infectious agent which is essential for
stimulation of protective immunity
• Subunit fish vaccines are commercially
available
• Example: IPN-vaccine for salmon fish
• Advantage: Safe and inexpensive
• Disadvantage: No intracellular replication
and inadequate cellular immunity
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45. Deletion mutant
• No deletion mutant fish vaccines are
commercially available
• Efficacy: Mimic pathogens and stimulate
mucosal immunity and cell-mediated
immunity
• Safety: Reversion to virulence less likely in
genetically engineered vaccines
• Can be used as marker or DIVA-vaccines
(differentiation infected from vaccinated)
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46. Live vectored vaccines
 Efficacy: can be used for viruses with no or
poor replication
 Cellular immunity is stimulated with the right
vector
 Safety: Safe, if the vector is non-pathogenic
 Several live vectored vaccines for terrestrial
animals, but none for fish
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47. DNA-vaccines
•Efficacy: A DNA-vaccine against IHN is
licenced in Canada
•The vaccine gives acceptable protection
•Safety: Fish vaccinated with DNA-vaccines are
considered to be gene modified organisms
(GMO) in some countries
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48. Future prospectus:-
 To achieve progress in fish vaccinology, an
increase in the co-operation between basic
and applied science is needed.
 Improvement in oral immunity with
biodegradable microparticle based vaccines
to be used for booster vaccination.

49.  Development of new non-mineral oil
adjuvants lacking side effects.
 Development of poly valent vaccines and
stabilization of a vaccine calendar appropriate
each economically important fish species.
 Investigation of the mechanisms of
immunoglobulin transfer from pre spanning
females to offsprings as a useful way of
protecting fish against pathogens which
affects early life stages.

50. SUMMARY
 Vaccination of aquatic animals is a basis for good
health, good economy and sustainability
 Efficacious vaccines are available for many diseases
 Main challenges for future development are
● live vaccines
● Oral vaccines
● Vaccines for virus and intracellular bacteria
● Effective adjuvants with minimal side-effects
 Molecular biology is a useful tool for research,
production and control of new fish vaccines
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51. 03/05/15 51
We make aquaculture progress

52. Thank you
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