1. Principles and methods of vaccine production and fish immunization

2. Techniques of immunisation
Concept of vaccination 
Vaccination - immune response induction
Vaccines - preparations of antigens from pathogens, rendered non-pathogenic, stimulates immune system of the animal to increase the resistance to the disease on natural encounter with the pathogen 
Vaccines 
Ideal vaccines are one which is inexpensive to produce, easy to administer, safe and effective.
Role of Vaccines 
Primary administration, sensitises the host and builds up a protective immune response by way of memory cells
Natural encounter with the pathogen acts as a booster

3. Vaccination vs chemotherapy: advantages and disadvantages
Sl.No
Vaccination
Chemotherapy / antibiotics 1
Prophylactic: few if any losses from a disease :
Curative: some mortalities before treatment is effective 2
Prophylactic for long duration with only one or two treatments
Prophylactic for only a short period; constant treatment required 3
Vaccination: all fish receive treatment
Mostly antibiotics are given in food, but sick fish are often anorexic and do not receive treatment 4
No toxic side effects, and healthy fish have better growth performance
Toxic side effects may be considerable: treatment relies on differential toxicity between host and the pathogen for a therapeutic index; growth often arrested

4. Vaccination vs chemotherapy: advantages and disadvantages
S.No
vaccination
chemotherapy/antibiotic 5
No accumulation of toxic residues :
Toxic residues remain: a time lapse is required between treatment and marketing of fish 6
Pathogen unlikely to develop resistance
Many bacteria develop resistance to antibiotics 7
No legal restriction on “safe” vaccines
Use of antibiotics are restricted due to risk of development of antibiotic resistant strains 8
Theoretically, can control any disease
Chemotherapy limited: cannot control viral diseases 9
No environmental impact
Chemicals may disrupt local environment

5. Types of vaccines Killed vaccines
Chemicals– Formalin, chloroform, phenol
Physical method - disruption by sonication
lysis with sodium hydroxide or the detergent sodium sulphate also used for experimental purposes
Heat killing - denatures proteins, oxidises lipids and destroys crucial antigenic sites present on the pathogens.

6. Types of vaccines Attenuated vaccines
Deliver protective antigens to the appropriate site and in the proper context to generate correct immune response.
Not normally used in fish due to the scare of reversion
Pathogen avirulent in the target species may cause infection in unrelated species and cause widespread infection.

7. Recent types of vaccines
Recently, new trends in vaccination have emerged incorporating latest techniques in biotechnology.
Subunit vaccines
Synthetic peptides
DNA vaccines
Mutant viruses.

8. Characteristics of vaccines
Safety
Immunogenicity
Stimulation of protective immunity
Efficacy of Vaccines
Specificity

9. Routes of administration of vaccines in fish
The vaccines are administered to the fish in a number of ways
Injection
immersion
hyper osmotic infiltration
Bath
spray and
oral modes

10. Relative percent survival (RPS)
is a measure of the potency of the vaccines and has to be checked invariably for all the vaccines to be marketed.
a minimum of 25 fish should be used for the experimentation.
% Mortality of vaccinated fish
RPS = 1 –  100
% Mortality of controls

11. Steps involved in the development of fish vaccines
Identification of disease problems and potential vaccines
Scientific Investigation
Disease pathology
Aetiology
Laboratory challenge system
Choice of antigens and vaccines formulation
Commercial considerations

12. Contd….. Production and testing Product licensing Laboratory testing
Initial field testing
Product licensing
Freedom from abnormal toxicity
Sterility
Safety
Potency
RPS should be more than 70 % for 10 day observation period

13. Contd…..
Stability
Presentation
After – Sales service