Lecture 5

Question 1

What are the non-specific defense mechanisms

Answer 1

• Surface barriers - mucus
  
  • Entraps and sloughs off - inhibiting colonisation
  • Mucus production increases in response to infection/inflammation
• Skin
  
  • Epidermis is non-keratinized and nucleated
  • Intergirty is vital to maintain osmotic balance and exclude micro organisms
  • Healing is rapid even at low temperatures

Question 2

What does melanin respond to

Answer 2

• Cytokines

Question 3

What are melanomacrophages

Answer 3

Melanin-producing cells originating from mesenchymal, hematopoietic stem cells

Question 4

What is hyper-pigmentation

Answer 4

• Non-specific indicator of chronic inflammation and/or poor-doing

Question 6

A non-specific defense mechanism: the gill

Answer 6

• A very large surface area of delicate epithelium
• Protected by mucus
• Also contains phagocytic cells

Question 7

A non-specific defense mechanism: GIT

Answer 7

• Mobile or circulating leukocytes are key cellular components of fish innate defense mechanism
• Monocytes, granulocytes, thrombocytes and non-specific cytotoxic cells
• Less mobile tissue granulocytes, eosinophilic granular cells, provoke immune defence against bacteria and parasitic worms at mucosal sites
• Leukocytes are not antigen-specific
• Cells possess pattern recognition proteins or receptors to recognise pathogens associated molecular patterns

Question 8

Name the phagocytes

Answer 8

• Monocytes
• Neutrophil
• B cells in fish

Question 9

Where are the macrophages located

Answer 9

• Gills, body cavity, mainly as RES cells in the kidney and spleen and cardiac atrium
• Monocytes found in the kidney and small numbers in blood
• Macrophages that contain mealnin - melano-macropahges
  *

Question 11

What contains neutrophils

Answer 11

• Kidney, spleen, blood and inflammatory lesions

Question 12

How is inflammation induced

Answer 12

H2O2 vasoactive amines, complement, eicosanoids and cytokines which are released in response to tissue damage or products of pathogens

Question 13

What immunoglobin do fish lack

Answer 13

IgA

Question 14

What is memory specific to

Answer 14

• Ag
• They have no obvious class switching
• Temperature dependent
• Establishment of memory also takes longer duration

Question 15

What are the factors affecting the immune response

Answer 15

• Extrinsic - environement and nature of antigen
• Intinsic - regulatory mechanisms within the immune system
• Physiological state of the animals including ontogenic factors

Question 17

What is the protection layer in crustaceans

Answer 17

Cuticles

Question 18

What do crustacenas lack

Answer 18

Immunoglobulins and complement factors

Question 20

What are hemocytes

Answer 20

• Antimicrobial peptides are major components involced in the defense mechanism of a wide range of organsisms, mainly exhibiting a broad spectrum of activites against G(+ve) and G(-) fungi and bacteria and viruses and are promarily expressed in circulating hemocytes - the main site for immune response
• Crustacean hemocytes can innately recognize invading microbes by the engagement of host pattern recognition proteins with pathogen-associated molecular patterns
• The humoral responses are mediated by molecules in haemolymp - the important humoral responses are melanin synthesis by the prophenoloxidase system, the blood clottign system and the generation of circulating antimicrobial peptides

Question 21

What do hemocytes carry out the functions of

Answer 21

Both red and white blood cells

Question 22

What are the three different subdivisions of hemocytes

Answer 22

• Hyaline
• Semi-granular
• Granular cells

Question 23

What are crustacean hyaline hemocytes involved in

Answer 23

Coagulation, encapsulation and nodulation of pathogens

Question 24

When does the humoral response arise

Answer 24

• When the extracellular signal molecules from pathogens, such as the PAMPs or the viral protein antigens are detected by the cell-surface receptors or PRPs resulting in the activation of signaling pathways

Question 25

What protects against salinity

Answer 25

Osmolytes in diet - betaine, inositol, taurine, glyverol, free amino acids

Question 27

What protects against heat shock

Answer 27

Betanine

Question 28

What is immune priming

Answer 28

• distinguishes the phenomena of some memory-like properties of cells like NK cells and macrophages from the classical immune memory triggered by T/B lymphocytes

Question 29

What are immunostimulants

Answer 29

• Increase the activity of the immune system and result in protection against crustacean pathogens - the protection they provide depends on general innate immunity as opposed to antigenic immune specificty

Question 31

What are passice vaccines

Answer 31

After immunizing animals with target antigens, egg yolk immunoglobulin from hens as well as antibodies from mammals can be collected and used as a passive vaccine fro shrimp and crayfish against pathogenic diseases

Question 32

What are RNAi vaccines

Answer 32

Deliver specific dsRNAs against essential specific genes from pathogens anf then trigger sequence-dependent as well as sequence-independent immune responses

Question 33

What are challenge immediately after final vaccination

Answer 33

• Inactivated pathogens or recombinant pathogenic surface proteins are delivered into shrimp and crayfish
• Immediate protection they provide may simply be due to receptor competition between the vaccine and target antigen