Acquired cell-mediated protection in rainbow trout, Oncorhynchus mykiss , against the haemoflagellate, Cryptobia salmositica

Abstract

Disease-free rainbow trout, Oncorhynchus mykiss (Walbaum),were inoculated with either the pathogenic Cryptobia salmositica Katz, 1951 or with the attenuated vaccine strain of the parasite. A number of vaccinated fish were then challenged at 6 weeks post-vaccination with pathogenic C. salmositica. Respiratory burst activity in stimulated macrophages (isolated from infected or vaccinated fish) was demonstrated by detection of released super-oxide anions, and the protein contents in these cells were also determined after the cells were digested. At 5 weeks after infection, the respiratory burst activity of macrophages from infected fish was significantly higher than those in naive and vaccinated fish. In addition, macrophages from vaccinated fish had greater activity than naive fish. Macrophage activity in vaccinated and challenged fish was comparable to that of infected fish. Antibodies were detected (ELISA) at 3 weeks after vaccination and at 5 weeks in infected fish. Complement-fixing antibodies (immune lysis test) were detected in infected fish at 5 weeks post-infection but were not detected in vaccinated fish unless they were challenged with the pathogen, in which case the titre rose rapidly.

Effect of Cryptobia salmositica-induced anorexia on feeding behavior and immune response in juvenile rainbow trout Oncorhynchus mykiss

“…Adhered macrophages were then washed with L-15 and incubated overnight with L-15 supplemented with 5% FBS at 14°C. Macrophages from each fish were subjected to the following treatments in triplicate: 100 µl of phorbol myristate acetate (PMA) at 1 mg ml -1 (Sigma), Cryptobia salmositica lysate (antigen) at 5 µg ml -1 (Mehta & Woo 2002) and Hank's balanced salt solution (HBSS). Cells were incubated for 3 h at 14°C before addition of 100 µl nitroblue tetrazolium (NBT) at 1 mg ml -1 in HBSS for 2 h at 14°C.…”

“…Humoral and cell-mediated immune responses are important mechanisms against cryptobiosis (Ardelli & Woo 2002, Mehta & Woo 2002. Live vaccine (attenuated Cryptobia salmositica) protects rainbow trout (Li & Woo 1995, Mehta & Woo 2002, chinook salmon (Staines & Woo 1997), brook charr (Ardelli & Woo 1997), and Atlantic salmon (Ardelli & Woo 2002) from this disease.…”

“…Live vaccine (attenuated Cryptobia salmositica) protects rainbow trout (Li & Woo 1995, Mehta & Woo 2002, chinook salmon (Staines & Woo 1997), brook charr (Ardelli & Woo 1997), and Atlantic salmon (Ardelli & Woo 2002) from this disease. Neutralizing, agglutinating, and complement-fixing antibodies have been detected in infected and vaccinated rainbow trout (Jones & Woo 1987, Li & Woo 1995, Mehta & Woo 2002.…”

“…Live vaccine (attenuated Cryptobia salmositica) protects rainbow trout (Li & Woo 1995, Mehta & Woo 2002, chinook salmon (Staines & Woo 1997), brook charr (Ardelli & Woo 1997), and Atlantic salmon (Ardelli & Woo 2002) from this disease. Neutralizing, agglutinating, and complement-fixing antibodies have been detected in infected and vaccinated rainbow trout (Jones & Woo 1987, Li & Woo 1995, Mehta & Woo 2002. Cell-mediated immune responses have been demonstrated, including delayed-type hypersensitivity reactions (Thomas & Woo 1990, Feng & Woo 1996, inhibition of macrophage migration (Thomas & Woo 1990), stimulation and growth of peripheral leukocytes with concovalin A (Ardelli & Woo 2002), and increased respiratory bursts killing macrophages in the head kidney (Mehta & Woo 2002).…”

Contribution of food deprivation to the immune response in rainbow trout ( Oncorhynchus mykiss ) vaccinated against Cryptobia salmositica and Aeromonas salmonicida

“…Enzyme-linked immunosorbent assay (ELISA; modified from Sitja-Bobadilla and Woo, 1994) Cryptobia salmositica antigen was prepared as described by Mehta and Woo (2002), and its concentration adjusted to 25 µg/ml with coating buffer (pH 9.6); this was used to detect circulating antibodies against C. salmositica. Formalin-killed A. salmonicida antigen (2 mg wet weight/ml; 50 µl) in 50 mM carbonate buffer (pH 9.6) was used to detect antibodies against the bacterium.…”