Farming of fish and shellfish has gained significant grounds in several parts of the world . Now a days disease is main problem in aquafarming. In recent years ,lot of attention is being given to health management using various forms of immunoprophylactic techniques such as vaccination and immunostimulation . To reduce immunoprophylactic application ,it is vital to have insight into specific and non specific defense mechanism of farmed animal . Through disease process studies ,it is very well known that a pathogen can cause disease only if it can overcome the non specific and specific defense barriers of the host and successfully establish and proliferate

2.  Farming of fish and shellfish has gained significant grounds in
several parts of the world .
 Now a days disease is main problem in aquafarming.
 In recent years ,lot of attention is being given to health
management using various forms of immunoprophylactic
techniques such as vaccination and immunostimulation .
 To reduce immunoprophylactic application ,it is vital to have
insight into specific and non specific defense mechanism of
farmed animal .
 Through disease process studies ,it is very well known that a
pathogen can cause disease only if it can overcome the non
specific and specific defense barriers of the host and successfully
establish and proliferate

3.  The immune system of fish is very similar to vertebrates,
although there are some important differences.
 The immune system ,vested with the role of defense is
composed of various cell type ,tissue and organ.
 The use of these products reduces the need for
therapeutic treatments, enhances the effects of vaccines
and, in turn, improves the indicators of production.

4. 1.Non specific
2.Specific immune system
 The former is encounter in almost all living organism
including fishes .It is non specific because the same
immune response can be elicited by number of
unrelated foreign particles .
 Specific or acquired mechanism of immunity is found
only in vertebrate and the reaction are directed
against specific molecules that stimulate such reaction
 Though these two mechanism appear as distinct in fact
they function in conjunction with each other ,making
the study of immunology a complex and vast one.

6.  Non adaptive immunity/ innate immunity
 The main determinants of innate immunity are genetically controlled
varying widely with species ,strain and to a lesser extent between
individuals.
 Some of the important components of non specific defense system
 1. integumental
 2. phagocytes
 3.tissue and serum
 4. other cells
 5.Inflammatory response
 6.Encapsulation
1 . Integumental : skin and mucus act as primary surface barriers to
several pathogenic agents. Continuous production and sloughing of
mucus keep the fish skin and gills free from pathogen colonization

7.  In addition , lytic property of mucus due to lysosomal enzyme
prevent colonization of skin and gills by the pathogen .Low ph
and mucus of alimentary tract offer similar protection against
colonization of gut by enteric pathogen
2. Fish have fixed and circulating phagocytes ,which act as the
main line of defense against pathogen which breaches the
primary line of integumentary barriers . Reticulo endothelial
system (RES)present in kidney ,spleen ,and heart ,phagocytes
destroy pathogen and also remove dead host tissue .
Several serum factors antibody and complement act as
opsonins and enhance the rate of phagocytosis .
Chemo tactic factors like macrophage aggregation
factor(MAF)and macrophage migration inhibition factor (MIF)
enhance the action of phagocytes at the site of injury..

9. 3. Tissue and serum components
A) c-reactive proteins (CRP) found in the serum bind to
phosSphoryl ester group and exhibit their antibacterial and
antifungal activity.CRP also act as opsonins and enhance
phagocytosis
B) Complement present in the serum are activated by the classical
and alternate pathway. In the classical pathway antibody
antigen complex activates the complement system are involved
in lysis ,chemo taxis
C) Proper din- a protein present in fish serum is activated by cell
wall product of bacteria and is involved in the activation of
complement through the alternate pathway .
D) Lysosomal enzyme present in mucus ,serum ,and phagocytes
cause lysis of pathogen .

10. E) Natural agglutinin and precipitin present in serum and
mucus agglutinate and precipitate particulate and soluble
antigen respectively.
F) Transferrin starves bacteria by binding iron in the serum.
G) Interferon produced by viral infected cells protects the
other potential host cell.
H) Lymphokines produced by t –lyphocytes specifically in
response to antigen have non specific effect on
inflammation and phagocytosis at the site of injury.

11. 4. Other cells;
 A)mast cell ; fish may not possess true mast cell
similar to the ones present in mammal, Histamin
contaning cells, such as eosinophilic granular
cells(EGC) present in integument ,gills and gut may
probably be mast cell analogue in fish

 B)natura l killer cell /non specific cytotoxic cell(nk/nc
cell)are belived to have a role in immobilizing and
killing viral infacted cells and pathogen like
i.Mullifilis


12. 5. Inflmmatory response : it is a well developed, non –specific,
vascular response aimed to destroy ,dilute or wall off the cause
of injury .
Inflammation is initiated as long as the functional blood supply
is present at the injured area .Inflammation is characterized by
reddining swelling pain, heat and loss of function.Vasoactive
amines released following tissue damage exert a significanes
influence on the microcircultion of the area .
6 encapsulation : in this type of response fibrous tissue composed
of collagen encapsulation the large parasite pathogen such as
digenetic trematodes and cestodes .

14. Specific defense system in all vertebrate including fish is characterized
by specificity and memory.
 Lymphocytes are central to specific defense system .
 There are two main population of lymphocytes namely B-lymphocytes
and T –lymphocytes.
 Fish have three major lymphoid organ thymus ,anterior kidney and
spleen.
 Thymus is regarded as the primary lymphoid organ.
 Thymus is the first organ to become lymphoid and provided the virigin
pool of lymphocyte to the secondary lymphoid organ namely kidney and
spleen .
 The lymphoid population in the secondary lymphoid organ perform the
vital function of immune responsiveness such as antigen recognition .
 The specific defense system has two arms
1 . Humoral immunity(B-cell)
2. Cell mediated immunity system(T-cell)

15. 1. Humoral immunity
B-lymphocyte differentiate into plasma cells which produce antibody
specific to the stimulating antigen and into memory cells which are capable
of becoming plasma cells on subsequent exposure to the same antigen .
Antibody neutrolise pathogen by agglutination ,percipitation neutrolisation
and complement activation .
2. Cell mediated immunity(CM
Different population of t- lymphocyte namely T- helper cells T-supressor cells
, T-killer cells and T-lymphokinin producing cells are involved in the
execution of CMI .This aspect of the immune response is wide ranging and
also recruit the macrophages which constitute the body’s main line of non
specific defense
Different function of T-lymphocyte
T-helper cells
T-killer cells
T-lymphokine producing cells
T-supressor cells

20.  Crustacean encounter a variety of pathogen in the environment they live in
 Though the specificity of crustacean defense mechanism is not comparable to
that of higher vertebrate or even fish ,the efficiency with their defense system
overcome the pathogenic hostility is highly remarkable .
 In crustacean nonspecific immune system has a greater role to play due to a
poorly developed specific immune system with a very weak or no memory
function in it.
 The defense in crustacean is largely dependent on the blood cells and
haemolymph activities
 Lot of interest is being generated towards understanding the basis of defense
mechanism in shrimp so as to develop practical immunoprophylactic
management tool to contain disease .they have well developed specific immune
system with no specific and memory
 One recent study has been describe that shrimp do have memory i.e they
showed enhance response to booster immunostimulation by glucan and there is
possibility of maternal transfer of immunity .shrimp do recognize self/non self

21. A) MOBILE DEFENSE
B) FIXED DEFENSE
C) PRO-PHENOLOXIDASE SYSTEM (PPO)

22. a) fixed defense
 Hard cuticle :- hard exoskeleton of crustacean acts as first line of
defense being structural and chemical barriers to several pathogen
.therefore ,the most vulnerable phase of the disease in the life cycle of
crustacean is the molting stage.
 During this stage parasite find it easy for attachment and penetration
which also leads to other infection and complexities
 Bronchial podocytes act as fixed phogocytic cells and remove pathogen
from hemolymph. Crustacean have remarkable ability for autotomy and
regeneration of appendages .
 Clotting and wound repair is rapid and well developed in crustacean.
B) MOBILE DEFENSE
1. Cellular
2. Humoral

23.  1. cellular : crustacean have an open circulating system having analogues
of white blood cells ,called hemocytes.crustacen have three types of
hemocyte namely hyaline cells ,semigronulocytes and
granulocytes.hyoline cells are primarily responsible for phagocytosis
while semi granulocytes and granulocytes perform the function of
encapsulation and nodule formation
 a) phagocytosis
 b) encapsulation
 c) nodule formation
 d) cytotoxicity
2. Humoral factor
 Humoral factor include large no. of lectine,lysine,agglutinin.
 Lectine bind to carbohydrate of foreign cells.
 Agglutini can help in adhesion of heamocyte to foreign cells
C) prophenol oxidase system(PPO)