Lecture 4 Flashcards
What is the immunity response of a fish
Occupy an apparent crossroads between the innate immune response and the emergence of the adaptive immune response
What are the first cells on site after an insult
Neutrophils
What affects the immunity of fish
- Environment
- Poikilothermic nature (NB)
What is the immunity of fish like
- Innate immunity as well as adaptice immunity, however the innate is stronger than adaptive
What organs deal with the immune system
- Lymphoid organ except lymph nodes and the bone marrow
Where is there the highest concentration of immune cells
Anterior kidney has highest concentration of developing B lymphoid cells
What is the head kidney
Aglomerular and assume haemopoietic functions - it is the principal immune organ responsible for phagocytosis, antigen processing and formation of IgM and immune memory through melanomachrophage centres
What is the pronephros
Head kidney
- formed by 2 arms that spread from cranial part of abdomen. It is near or associated with gill
- Endocrine organ - similar to adrenal gland (corticosteroids)
- Major site of antibody production
*
Function of the spleen
- Secondary immune organ - IgM and mature B ceels
- Clearance of blood-borne antigens and immune complexes in the splenic ellipsoids and in antigen presentation
- Haematopoiesis, antigen degradation in antibody production processing
- Sleen alone plays an essential role in antigen trapping
What is the thymus
- Subepithelial organ
- Only produces T lymphocyte
What does the thymus produce
T lymphocytes
What is the GALT
- Gut associated lymphoid tissue
- Mainly of lymphocytes, plasma cells and macrophages
What kind of lymphoids does the musoca have
B
What leukocytes are found in fish
- Neutrophils, monocytes, thrombocytes, plasma cells, B cells, T cells, NK cells and ‘esinophils’
What are non-specific immune elements
- Act as first line of defence against all pathogens, but also play an instructive role in the development of acquired immune response
- Elements of non-specific immune components include antibacterial peptides, lysozyme, lectins, acute phase proteins and the complement system
What do lysozyme act on and where is synthesised
Bacterium cell wall
In the liver
Where is lysozyme found
Mucous
What are lectins
Proteins of non-immune origin
- Bind to certain sugars
- Opsonin for phagocytosis becteria and is alos involved in activation of the complement system
What is the C-reactive protein
- Acute phase proteins function in a variety defence-related activities such as limiting the dispersal of infectious agents, inactivation of proteases, killing microbes and repair of tissue damage
- Involed in classical pathway - enchance phagocytosis, C reactive protein is NB
- Increase 20- fold foling high temperature shock or administration of inflammatory agents
What is the purpose of the complement system
- Links innate and adaptive immune reponses - complements the ability of antibodies and phagocytic cells to clear pathogens
Explain the alternative complement pathway
Antibody independent, is very prominent in fish serum
What is the role of complement
Killing of pathogens through opsonisation and activation of phagocytes
What are the elements involved in innate and adaptive immunity
- Lymphocytes, NK cells and MHC
What is the innate control of adaptive immunity
Is based on establishing an association between the Ag recognition by lymphocytes and the pathogen associated molecular patterns (PAMPs)
What is sinilar to NK cells
Non-specific cytotoxic cells (NCCs)
What is the most primitive vertebrates to possess an adaptive immune system
- Fish
- Lymphocytes, immunoglobulins, T cell receptor and products of major histocompatibility complec to allow the clonal selection of B and T cells
What have fish been shown to have
- Lymphocyte subpopulations analogues to the mammalian B cells and T cells - the Ab representative in teleosts is more limited to mammals being IgM tetramer in the most prevalent form (produce by B cells)
- Mammalian IgM is a pentamere structure
What are the two heavy chain isotypes
IgD and IgT (IgZ was also reported in fish)
Where is IgM found
Epithelial mucus
What do T cells do
Release factors to cordinste responses of other immune cells or cytotoxic factors to directly kill infected or abnormal cells
How a B cells characterised
By expression of surface immunoglobulin receptors
How does resistance and recovery of infection happen
Are the result of complex interactions between non-specific and specific defense mechanisms
What are cytokines
- Act as modulators
- Innate and adaptive immune resposne
What is interleukin 1B mainly produced by
Macrophages
What is acquired immunity mediated by
Lymphocytes and affected mainly through antibodies
What are typical fish vaccines
Water-oil based
What is the best method of protection
Prevention: reduce the need for antibiotics and chemicals
When were vaccines licenced in the USA
1970’s
How are ERM and Vibrios vaccines administered
By immersion
How is furunculosis vaccine administered
Adjuvant and administered by injection to increase immunogenicity
What are the vaccines against Aeromonas salmonicida
- Aquavac
- Furovac
- Aquafur
- Furogen
- Biojec1500, 1800
What are the combination vaccines against Aeromonas salmonicida and Vibrio angullarum
- Norvax
- FUR VIB
Why are vaccines the best method
- Best survival rate and profitibility in aquaculture survival rate
- Good nutrition
- High-quality fingerlings quality fingerlings
- Good farming and husbandry practices
- Health management
What are the fish vaccination methods
- Reccomeded for only healthy fish
- Fish subjected to a dry curfew, deprived of food prior to vaccination suffer less handling stress and respond better to anaesthetics
- Disease free environment during the vaccination period
- Must precede exposure to disease or transfer to a disease prone site by the relevant/appropriate time - lag phase
How is delivery of vaccine done
- Injection: most effective but need anaesthetise and handle the fish
- Immersion: practical for mass vaccination of small fish only, does not work on all vaccines
- Oral: only suitable for mass vaccination but dosage uncertain and sometimes poor potency
What are the two application methods for immersion
- Dip vac
- Small fish immersed for very short duration in high concentration
- Used for a large number of fish
- Bath cac
- Larger fish are exposed for a longer period, usually one to several hours, in a lower concentration of vaccine
What are the limitations of a dip vaccination
- Duration of immunity is not very long and boster vaccine is required
- Impractical for larger fish due to cost effectiveness and the stress that could induce by vaccination
- In fish smaller than 1g the immune system might still be immature
How is injection of fish done
- Intraperitoneal or intramuscular - IP most common form in aquaculture
Advantage of injectables
- Long duration of protection
- Multiple antigens can be combined in a single vaccine and, therefore, in a single administration
- Every antigen can be combined in a single vaccine and therefore, in a single adminstration
- Every fish in the population has recieved the vaccine anf at the correct dose
- Injections are in general superior to any other vaccine application method; however from a practical point of view they can only be applied to fish of 10g or more
What do adjuvants promote
- Adhesion
- Autoimmune disease
Explain Adhesions
- Following IP vaccineation with multivalent, oil-adjuvanted vaccines
- Inflammatory response > docal and/or diffuse peritonitis with adhesions between viscera and abdominal wall
- Scoring scale from 0-6 based on macroscopic pathology findings
- At water temp of 10-12 degrees, the progression of injection-site reaction in Atlantic salmon may take 6-12 months
Explain the melanisation score
- 0 = no melanin
- 1 = small amount on viscera
- 2 = Highly visible melanin and/or slight pigmentation of abdominal wall which is easily removed
- 3 = melanisation of abdominal wall and of abdominal wall fillet - removal results in damage and removal results in damage and downgrading
What are the 3 criteria used for vaccine efficacy
- Rate at which protection is achieved
- The final degree of protection: relative precent survival
- Duration of immunity
How to measure immune response
- Blood parameters
- Identification of cells types and how these populations change
- Simple functional assay
- Easy to measure IgM by ELISA but not IgT
- Gene expression
