Current research status of fish immunostimulants

doi:10.1016/S0044-8486(98)00436-0

Aquaculture

Volume 172, Issues 1–2, 1 March 1999, Pages 63-92

https://doi.org/10.1016/S0044-8486(98)00436-0 Get rights and content

Abstract

Immunostimulants are valuable for the control of fish diseases and may be useful in fish culture. The immunostimulatory effects of glucan, chitin, lactoferrin and levamisole for fish and shrimp have been reported. Nutritional factors such as Vitamins B and C, growth hormone and prolactin have also been reported to be immunostimulators. These immunostimulants mainly facilitate the function of phagocytic cells and increase their bactericidal activities. Several immunostimulants also stimulate the natural killer cells, complement, lysozyme and antibody responses of fish. The activation of these immunological functions is associated with increased protection against infectious disease. Resistance to bacterial pathogens such as Vibrio anguillarum, V. salmonicida, Aeromonas salmonicida, Yersinia rukeri and Streptococcus spp. and to parasitic infections such as white spot disease can be increased by administration of immunostimulants, but not to intracellular pathogens such as Renibacterium salmoninarum and Pasteurella piscicida. The most effective method of administration of immunostimulants to fish is by injection. Oral and immersion methods have also been reported, but the efficacy of these methods decreases with long-term administration. Overdoses of several immunostimulants induce immunosuppression in fish. The side effects of immunostimulants have not been well-studied. Growth-promoting activity has been noted in fish or shrimp treated with glucan or lactoferrin. Immunostimulants can overcome immune suppression by sex hormones. Thus, the influence of immunostimulants in mature fish should be studied. In conclusion, immunostimulants can reduce the losses caused by disease in aquaculture; however, they may not be effective against all diseases. For the effective use of immunostimulants, the timing, dosages, method of administration and the physiological condition of fish need to be taken into consideration.

Introduction

Fish culture is an important industry. Various kinds of marine and freshwater fish have been cultured and the worldwide production of cultured fish increases every year. Fishes are usually cultured in enclosed spaces such as ponds or net cages and efforts have been made to increase productivity per unit space. Overcrowding tends to adversely affect the health of cultured fish. These conditions tend to produce poor physiological environment for fish and increase susceptibility to infections.

Various chemotherapeutics have been used to treat bacterial infections in cultured fish for about the last 20 years. However, the incidence of drug-resistant bacteria has become a major problem in fish culture (Aoki, 1992). Vaccination is a useful prophylaxis for infectious diseases of fish and is already commercially available for bacterial infections such as vibriosis, redmouth disease and furunculosis and for viral infection such as IPN. Vaccination may be the most effective method of controlling fish disease. Furthermore, the development of vaccines against intracellular pathogens such as Renibacterium salmoninarum has not so far been successful. Therefore, the immediate control of all fish diseases using only vaccines is impossible.

Immunostimulants increase resistance to infectious disease, not by enhancing specific immune responses, but by enhancing non-specific defense mechanisms. Therefore, there is no memory component and the response is likely to be of short duration. Use of these immunostimulants is an effective means of increasing the immunocompetency and disease resistance of fish. Research into fish immunostimulants is developing and many agents are currently in use in the aquaculture industry.

Use of immunostimulants, in addition to chemotheraputic agents and vaccines, has been widely accepted by fish farmers. Many questions about the efficacy of immunostimulants from users still remain (for example, whether immunostimulants can protect against all infectious diseases). In this review, the current status of immunostimulant research will be discussed.

Section snippets

Fish defense system enhancement by immunostimulants

The fish defense system (Iwama and Nakanishi, 1996) is basically similar to that described in mammals. For cellular defense systems, teleosts have phagocytic cells similar to macrophages, neutrophils, and natural killer (NK) cells, as well as T and B lymphocytes. Teleosts also have various humoral defense components such as complement (classical and alternative pathways), lysozyme, natural hemolysin, transferrin and C-reactive protein. The existence of cytokines (interferon, interleukin 2,

Immunostimulants studied in fish and shellfish

Table 1 lists those immunostimulants reported to be effective in fish and shellfish. In this review, immunostimulants include chemical agents, bacterial components, polysaccharides, animal or plant extracts, nutritional factors and cytokines.

Therapeutic regiments for immunostimulant application

The use of immunostimulants can protect fish from several infectious diseases and decrease mortality rates (Table 6); however, fish cannot be protected against all infectious diseases by immunostimulants. Fishes receiving immunostimulants show increased resistance against infection by bacteria such as V. anguillarum, V. salmonicida, A. salmonicida, and Streptococcus sp., viral infection such as IHN and yellow-head baculovirus, and parasite infection such as white spot disease. Positive effects

Timing of immunostimulants administration

The effect of timing the administration on immunostimulant function is a very important issue. Usually, the most effective timing of antibiotics is upon the occurrence of disease, and they cannot often be used prophylactically due to risk of fostering the development of drug-resistant bacteria. Anderson (1992)proposed that immunostimulants should be applied before the outbreak of disease to reduce disease-related losses.

Immunostimulants can promote recovery from immunosuppression states caused

Route of administration

Many authors reported that the injection of immunostimulants enhances the function of leucocytes and protection against pathogens. However, this method is labor intensive, relatively time-consuming and becomes impractical when fishes weigh less than 15 g. Thus, another method such as oral administration or immersion should be used. Oral administration of immunostimulants has already been reported for glucans, EF203, lactoferrin, levamisole and chitosan. This method is non-stressful and allows

Doses

Immunostimulants increase the immune responses and enhance protection against pathogens which raises the question of dose-dependency. Kajita et al. (1990)showed that the chemiluminescent effects of phagocytic cells in rainbow trout were increased by injection of levamisole at 0.1 and 0.5 mg/kg. However, they also reported that the injection of 5 mg/kg of levamisole did not produce this immunostimulant effect. Robertsen et al. (1994)reported that the increase in respiratory burst activity of

The effects of long-term administration

Oral administration is the most practical method for delivery of immunostimulants; however, the effects of long-term oral administration of immunostimulants are still unclear. Matsuo and Miyazano (1993)reported that rainbow trout treated with peptidoglucan orally for 56 days did not show protection after challenge with V. anguillarum, although fish treated for 28 days showed increased protection. Yoshida et al. (1995)also demonstrated that the number of NBT-positive cells in African catfish

The additional effects of immunostimulants

Several authors have reported relationships between immunostimulation and growth-promoting activity. Boonyaratpalin et al. (1995)reported that black tiger shrimp fed with peptidoglycan-supplemented feed showed better growth and feed conversion rates than those fed a normal diet. This effect was observed with 0.01% peptidoglycan supplementation, but not with the highest level administered (0.1%). Sung et al. (1994)also showed that black tiger shrimp grew faster with glucan immersion at the 0.5,

Conclusions

In this review, the benefits of immunostimulants for aquaculture were discussed. The characteristics of immunostimulants are shown in Table 7. There are mainly three methods for control of fish disease: vaccination, chemotheraputics and immunostimulants. Both immunostimulants and vaccines are used to prevent infectious diseases. However, we cannot expect the marked or long-term effects observed with vaccines to occur with immunostimulants. Although immunostimulants may be used for treatment of

References (144)

R Aakre et al.
Enhanced antibody response in Atlantic salmon (Salmo salar L.) to Aeromonas salmonicida cell wall antigens using a bacterin containing β-1, 3-M-glucan as adjuvant
Fish Shellfish Immunol.
(1994)
A Adams et al.
The potency of adjuvanted injected vaccines in rainbow trout (Salmo gairdneri Richardson) and bath vaccines in Atlantic salmon (Salmo salar L.) against furunculosis
Aquaculture
(1988)
D.P Anderson
Immunostimulants, adjuvants, and vaccine carriers in fish: applications to aquaculture
Annu. Rev. Fish Dis.
(1992)
V.S Blazer
Nutrition and disease resistance in fish
Annu. Rev. Fish Dis.
(1992)
V.S Blazer et al.
The effects of α-tocopherol on the immune response and non-specific resistance factors of rainbow trout (Salmo gairdneri Richardson)
Aquaculture
(1984)
L.W Clem et al.
Monocytes as accessory cells in fish immune responses
Dev. Comp. Immunol.
(1985)
R.E Engstad et al.
Yeast glucan induces increase in activity of lysozyme and complement-mediated haemolytic activity in Atlantic salmon blood
Fish Shellfish Immunol.
(1992)
J.I Erdal et al.
Relationship between diet and immune response in Atlantic salmon (Salmo salar L.) after feeding various levels of ascorbic acid and omega-3 fatty acids
Aquaculture
(1991)
A Gildberg et al.
Isolation of acid peptide fractions from fish protein hydrolysate with strong stimulatory effect on Atlantic salmon (Salmo salar) head kidney leucocytes
Comp. Biochem. Physiol.
(1996)
L.J Hardie et al.
THe effect of vitamin E on the immune response of Atlantic salmon (Salmo salar)
Aquaculture
(1990)

G Rørstad et al.

Adjuvant effect of a yeast glucan in vaccines against furunculosis in Atlantic salmon (Salmo salar L.)

Fish Shellfish Immunol.

(1993)

G.L Rumsey et al.

Effect of soybean protein on serological response, non-specific defense mechanisms, growth, and protein utilization in rainbow trout

Vet. Immunol. Immunopathol.

(1994)

Ainsworth, A.J., Mao, C.P., Boyle, C.R., 1994. Immune responses enhancement in channel catfish, Ictalurus punctatus,...

D.R Amberuso et al.

Lactoferrin enhances hydroxyl radical production by human neutrophils, neutrophil particulate and an enzymatic generating system

J. Clin. Invest.

(1981)

D.P Anderson et al.

Duration of protection against Aeromonas salmonicida in brook trout immunostimulated with glucan or chitosan by injection or immersion

Prog. Fish Cult.

(1994)

Anderson, D.P., Siwicki, A.K., Rumsey, G.L., 1995. Injection or immersion delivery of selected immunostimulants to...

Aoki, T., 1992. Chemotherapy and drug resistance in fish farms in Japan. In: Shariff, M., Subasighe, R.P., Arthur, J.R....

R.R Arnold et al.

Bactericidal activity of human lactoferrin: sensitivity of a variety of microorganisms

Infect. Immun.

(1980)

C.J Auernhammer et al.

Effects of growth hormone and insulin-like growth factor 1 on the immune system

Eur. J. Endocrinol.

(1995)

T Baba et al.

Activation of mononuclear phagocyte function by levamisole immersion in carp

Nippon Suisan Gakkaishi

(1993)

T.J Baldwin et al.

Pathogenesis of enteric septicemia of channel catfish, caused by Edwardsiella ictaluri: bacteriological and light and electron microscope findings

J. Aquat. Anim. Health

(1996)

M.O.D Baulny et al.

Effect of long-term oral administration of β-glucan as an immunostimulant or an adjuvant on some non-specific parameters of the immune response of turbot Scophthalmus maximus

Dis. Aquat. Org.

(1996)

Berczi, I., Nagy, E., 1987. The effect of prolactin and growth hormone on hemolymphopoietic tissue and immune function....

Boonyaratpalin, S., Boonyaratpalin, M., Supamattaya, K., Toride, Y., 1995. Effects of peptidoglucan (PG) on growth,...

C.A Bortner et al.

Bactericidal effect of lactoferrin on Legionella pneumophila

Infect. Immun.

(1986)

J.A Calduch-Giner et al.

Evidence for a direct action of GH on haemopoietic cells of a marine fish, the gilthead sea bream (Sparus aurata)

J. Endocrinol.

(1995)

K.L Chang

Experimental studies on biochemical characters of Achromobacter stenohalis

J. Jinsen Med. Sci.

(1966)

D Chen et al.

Glucan administration potentiates immune defense mechanisms of channel catfish, Ictalurus punctatus Rafineque

J. Fish Dis.

(1992)

R.A Dalmo et al.

The immunomodulatory effect of LPS, laminaran and sulfated laminaran [β(1, 3)-d-glucan] on Atlantic salmon, Salmo salar L., macrophages in vitro

J. Fish Dis.

(1995)

J.F Davis et al.

The enhancement of resistance of the American eel, Anguilla rostrata Le Sueur, to a pathogenic bacterium Aeromonas hydrophila, by an extract of the tunicate Ecteinascidia turbinata

J. Fish Dis.

(1984)

P.L Duncan et al.

Dietary immunostimulants enhance nonspecific immune responses in channel catfish but not resistance to Edwardsiella ictaluri

J. Aquat. Anim. Health

(1996)

P.L Duncan et al.

Effects of feeding Spirulina on specific and nonspecific immune responses of channel catfish

J. Aquat. Anim. Health

(1996)

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Current research status of fish immunostimulants

Abstract

Introduction

Section snippets

Fish defense system enhancement by immunostimulants

Immunostimulants studied in fish and shellfish

Therapeutic regiments for immunostimulant application

Timing of immunostimulants administration

Route of administration

Doses

The effects of long-term administration

The additional effects of immunostimulants

Conclusions

Fish Shellfish Immunol.

Aquaculture

Annu. Rev. Fish Dis.

Annu. Rev. Fish Dis.

Aquaculture

Dev. Comp. Immunol.

Fish Shellfish Immunol.

Aquaculture

Comp. Biochem. Physiol.

Aquaculture

Aquaculture

Fish Shellfish Immunol.

Aquaculture

Dev. Comp. Immunol.

Fish Shellfish Immunol.

Biochem. Pharmacol.

Dev. Comp. Immunol.

Aquaculture

J. Nutr.

Aquaculture

Curr. Opin. Immunol.

Aquaculture

Fish Shellfish Immunol.

Dev. Comp. Immunol.

Vet. Immunol. Immunopathol.

Aquaculture

Fish Shellfish Immunol.

Fish Shellfish Immunol.

Fish Shellfish Immunol.

Vet. Immunol. Immunopathol.

Lactoferrin enhances hydroxyl radical production by human neutrophils, neutrophil particulate and an enzymatic generating system

J. Clin. Invest.

Duration of protection against Aeromonas salmonicida in brook trout immunostimulated with glucan or chitosan by injection or immersion

Prog. Fish Cult.

Bactericidal activity of human lactoferrin: sensitivity of a variety of microorganisms

Infect. Immun.

Effects of growth hormone and insulin-like growth factor 1 on the immune system

Eur. J. Endocrinol.

Activation of mononuclear phagocyte function by levamisole immersion in carp

Nippon Suisan Gakkaishi

Pathogenesis of enteric septicemia of channel catfish, caused by Edwardsiella ictaluri: bacteriological and light and electron microscope findings

J. Aquat. Anim. Health

Effect of long-term oral administration of β-glucan as an immunostimulant or an adjuvant on some non-specific parameters of the immune response of turbot Scophthalmus maximus

Dis. Aquat. Org.

Bactericidal effect of lactoferrin on Legionella pneumophila

Infect. Immun.

Evidence for a direct action of GH on haemopoietic cells of a marine fish, the gilthead sea bream (Sparus aurata)

J. Endocrinol.

Experimental studies on biochemical characters of Achromobacter stenohalis

J. Jinsen Med. Sci.

Glucan administration potentiates immune defense mechanisms of channel catfish, Ictalurus punctatus Rafineque

J. Fish Dis.

The immunomodulatory effect of LPS, laminaran and sulfated laminaran [β(1, 3)-d-glucan] on Atlantic salmon, Salmo salar L., macrophages in vitro

J. Fish Dis.

The enhancement of resistance of the American eel, Anguilla rostrata Le Sueur, to a pathogenic bacterium Aeromonas hydrophila, by an extract of the tunicate Ecteinascidia turbinata

J. Fish Dis.

Dietary immunostimulants enhance nonspecific immune responses in channel catfish but not resistance to Edwardsiella ictaluri

J. Aquat. Anim. Health

Effects of feeding Spirulina on specific and nonspecific immune responses of channel catfish

J. Aquat. Anim. Health