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Immunological and therapeutic strategies against salmonid cryptobiosis.

Woo PT - J. Biomed. Biotechnol. (2009)

Bottom Line: MAb-001 does not fix complement but agglutinates the parasite.Complement fixing antibody production and cell-mediated response in vaccinated fish rise significantly after challenge.Isometamidium chloride is therapeutic against the pathogen and its effectiveness is increased after conjugation to antibodies.

View Article: PubMed Central - PubMed

Affiliation: Department of Integrative Biology, University of Guelph, Guelph, ON, Canada.

ABSTRACT
Salmonid cryptobiosis is caused by the haemoflagellate, Cryptobia salmositica. Clinical signs of the disease in salmon (Oncorhynchus spp.) include exophthalmia, general oedema, abdominal distension with ascites, anaemia, and anorexia. The disease-causing factor is a metalloprotease and the monoclonal antibody (mAb-001) against it is therapeutic. MAb-001 does not fix complement but agglutinates the parasite. Some brook charr, Salvelinus fontinalis cannot be infected (Cryptobia-resistant); this resistance is controlled by a dominant Mendelian locus and is inherited. In Cryptobia-resistant charr the pathogen is lysed via the Alternative Pathway of Complement Activation. However, some charr can be infected and they have high parasitaemias with no disease (Cryptobia-tolerant). In infected Cryptobia-tolerant charr the metalloprotease is neutralized by a natural antiprotease, alpha2 macroglobulin. Two vaccines have been developed. A single dose of the attenuated vaccine protects 100% of salmonids (juveniles and adults) for at least 24 months. Complement fixing antibody production and cell-mediated response in vaccinated fish rise significantly after challenge. Fish injected with the DNA vaccine initially have slight anaemias but they recover and have agglutinating antibodies. On challenge, DNA-vaccinated fish have lower parasitaemias, delayed peak parasitaemias and faster recoveries. Isometamidium chloride is therapeutic against the pathogen and its effectiveness is increased after conjugation to antibodies.

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Related in: MedlinePlus

Cryptobia salmositica with red cell from an experimentally infected rainbow trout (reproduced from Woo [5]).
© Copyright Policy - open-access
Related In: Results  -  Collection


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fig1: Cryptobia salmositica with red cell from an experimentally infected rainbow trout (reproduced from Woo [5]).

Mentions: Salmonid cryptobiosis is caused by the haemoflagellate Cryptobia (Trypanoplasma) salmositica (Figure 1). The pathogen has been reported in all species of Pacific salmon, Oncorhynchus spp., along the west coast of North America [5], and outbreaks of cryptobiosis with high fish mortalities have occurred in both freshwater hatcheries and in sea cage cultures [6]. The parasite multiplies by binary fission, and the parasitaemia peaks at about 4-5 weeks after infection (e.g., [7–9]). The severity of the disease (e.g., the anaemia) is directly related to the parasitaemia and clinical signs include exophthalmia (Figure 2), general oedema, abdominal distension with ascites, a microcytic and hypochromic anaemia, positive antiglobulin reaction (or positive Coombs' test) of red cells (Figure 3), and anorexia [7, 10, 11]. Anorexia is a double-edged sword—it is beneficial to the host in that it reduces the severity of the disease by lowering plasma proteins and subsequently the parasitaemia but it is also detrimental to the fish in that it contributes to the immunodepression [11, 12]. During acute disease the haemolytic activity of complement is significantly lowered [13]. In addition, plasma thyroxine (T3 and T4), protein, and glucose are reduced along with depletion of liver glycogen [14]. The metabolism and swimming performance of infected rainbow trout are also significantly reduced [15], and the bioenergetic cost of the disease in juvenile fish is considerable. These are contributing factors to the retarded growth as there are significant reductions in food consumption, dry weight and energy gained, energy concentration, and gross conversion efficiency. However, the attenuated vaccine strain (Section 3.3.1) has no detectable bioenergetic cost to juvenile fish [16].


Immunological and therapeutic strategies against salmonid cryptobiosis.

Woo PT - J. Biomed. Biotechnol. (2009)

Cryptobia salmositica with red cell from an experimentally infected rainbow trout (reproduced from Woo [5]).
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2801003&req=5

fig1: Cryptobia salmositica with red cell from an experimentally infected rainbow trout (reproduced from Woo [5]).
Mentions: Salmonid cryptobiosis is caused by the haemoflagellate Cryptobia (Trypanoplasma) salmositica (Figure 1). The pathogen has been reported in all species of Pacific salmon, Oncorhynchus spp., along the west coast of North America [5], and outbreaks of cryptobiosis with high fish mortalities have occurred in both freshwater hatcheries and in sea cage cultures [6]. The parasite multiplies by binary fission, and the parasitaemia peaks at about 4-5 weeks after infection (e.g., [7–9]). The severity of the disease (e.g., the anaemia) is directly related to the parasitaemia and clinical signs include exophthalmia (Figure 2), general oedema, abdominal distension with ascites, a microcytic and hypochromic anaemia, positive antiglobulin reaction (or positive Coombs' test) of red cells (Figure 3), and anorexia [7, 10, 11]. Anorexia is a double-edged sword—it is beneficial to the host in that it reduces the severity of the disease by lowering plasma proteins and subsequently the parasitaemia but it is also detrimental to the fish in that it contributes to the immunodepression [11, 12]. During acute disease the haemolytic activity of complement is significantly lowered [13]. In addition, plasma thyroxine (T3 and T4), protein, and glucose are reduced along with depletion of liver glycogen [14]. The metabolism and swimming performance of infected rainbow trout are also significantly reduced [15], and the bioenergetic cost of the disease in juvenile fish is considerable. These are contributing factors to the retarded growth as there are significant reductions in food consumption, dry weight and energy gained, energy concentration, and gross conversion efficiency. However, the attenuated vaccine strain (Section 3.3.1) has no detectable bioenergetic cost to juvenile fish [16].

Bottom Line: MAb-001 does not fix complement but agglutinates the parasite.Complement fixing antibody production and cell-mediated response in vaccinated fish rise significantly after challenge.Isometamidium chloride is therapeutic against the pathogen and its effectiveness is increased after conjugation to antibodies.

View Article: PubMed Central - PubMed

Affiliation: Department of Integrative Biology, University of Guelph, Guelph, ON, Canada.

ABSTRACT
Salmonid cryptobiosis is caused by the haemoflagellate, Cryptobia salmositica. Clinical signs of the disease in salmon (Oncorhynchus spp.) include exophthalmia, general oedema, abdominal distension with ascites, anaemia, and anorexia. The disease-causing factor is a metalloprotease and the monoclonal antibody (mAb-001) against it is therapeutic. MAb-001 does not fix complement but agglutinates the parasite. Some brook charr, Salvelinus fontinalis cannot be infected (Cryptobia-resistant); this resistance is controlled by a dominant Mendelian locus and is inherited. In Cryptobia-resistant charr the pathogen is lysed via the Alternative Pathway of Complement Activation. However, some charr can be infected and they have high parasitaemias with no disease (Cryptobia-tolerant). In infected Cryptobia-tolerant charr the metalloprotease is neutralized by a natural antiprotease, alpha2 macroglobulin. Two vaccines have been developed. A single dose of the attenuated vaccine protects 100% of salmonids (juveniles and adults) for at least 24 months. Complement fixing antibody production and cell-mediated response in vaccinated fish rise significantly after challenge. Fish injected with the DNA vaccine initially have slight anaemias but they recover and have agglutinating antibodies. On challenge, DNA-vaccinated fish have lower parasitaemias, delayed peak parasitaemias and faster recoveries. Isometamidium chloride is therapeutic against the pathogen and its effectiveness is increased after conjugation to antibodies.

Show MeSH
Related in: MedlinePlus