Fish Immunity and Nutrition
Outline of Presentation
1) General overview of immunology
2) Nutrients affecting immunity and
disease resistance
3) Non-nutrient immunostimulants
Glucans
Nucleotides
Prebiotics
4) Summary and conclusions
Verlhac and Gabaudan1997
Innate (Non-specific) Immunity
First line of defense, includes:
?Physical barriers (skin and mucus)
?Humoral factors
?Complement system
?Classical and alternative activation
?Lysozyme
?Lectins
?Cellular mechanisms
–Macrophages and neutrophils
?Chemotaxis
?Phagocytosis
?Oxygen-dependent and -independent killing –Extracellular killing
?Natural killing cells and eosinophils
Innate Immune Responses V. Verlhac, ISNFF, Brazil 2008
V. Verlhac, ISNFF, Brazil 2008
Adaptive Immunity Adaptive Immunity is antigen-specific Components include:
?Antibodies (immunoglobulins): IgM
?Produced by B lymphocytes:
recognize extracellular antigens
(humoral antibody system)
?Cell mediated Immunity: T lymphocytes (cellular system)
?T lymphocytes recognize
intracellular antigens expressed
on the surface of body cells
V. Verlhac, ISNFF, Brazil 2008
Assessment of Immune Responses ?The immune response as quite complex
–Measuring singular responses can be misleading ?The best measure of integrated immune
responses is a live pathogen challenge
?There is good correlation between immune
modulation and disease resistance when
immunity is broadly characterized
Nutrition and Immunity ?Nutrition is an important factor influencing immune responses and disease resistance
–Feed quality/quantity
–Nutrient availability
–Anti-nutritional factors
–Immunostimulants
?Disease or stress correspond to a break in immunocompetence
?Nutritional intervention can help manage disease by applying nutrition-based strategies which support optimal growth and immune
system function
?Over -fortification of certain nutrients ?Dietary supplementation of non -nutrient immunostimulants ?Functions (substrate vs. signal) and
actions of these various compounds is currently incomplete
Dietary Modulation of
Immunity and Disease Resistance
Nutrient allowance Verlhac and Gabaudan1997
Non-Nutritive Dietary Supplements Immunostimulants
?heterogeneous group including
-β-glucans
-nucleotides
-chitin
-peptidoglycan
-lipopolysaccharides
-levamisole
-prebiotics
Mechanisms of action
?complement activation
?enhanced lysozyme production
?increased oxidative capacity of phagocytes
Injection has generally produced more favorable responses than oral administration (~0.2% of diet); immunosuppression may occur
Cumulative Mortality of Hybrid Striped Bass Exposed to S. iniae
b
b
b
a
glucan
05101520253035404550M o r t a l i t y (%)
Control
0.05%
0.10%
0.20%
Diet
-disease and wound repair increase needs V. Verlhac, ISNFF, Brazil 2008
Nucleotides Enhanced resistance to infection by bacterial, viral, rickettsial and ectoparasitic organisms has been reported in salmonids.
Alterations in non-specific immune responses not consistently reported although potential mechanisms of action include:
?complement activation ?enhanced lysozyme production ?activation of macrophages ?increase natural killer cell activity
Cumulative Mortality of Hybrid Striped Bass Exposed to S. iniae
P = 0.091
5
152535455565758595M o r t a l i t y (%)
Control
Nucleotide
Diet
Exp. 1Exp. 2 P = 0.017
Li et al. (2004) Fish & Shellfish Immunol. 16:561-569