Biological characterization of a monoclonal antibody against a surface membrane antigen on Cryptobia salmositica Katz, 1951

A monoclonal antibody (IgG 1) (designated as MAb-001) was produced against the pathogenic haemoflagellate Cryptobia salmontica Katz. The antibody agglutinated live parasites under in vitro conditions. Live C. salmositica, incubated with MAb-001 at 10 °C, did not multiply and were dead within 4 weeks in culture. About 50% of juvenile rainbow trout, Oncorhynchus mykiss (Walbaum), inoculated intraperhoneally with C. salmositica, incubated in MAb-001 prior to inoculation, did not become infected, while in adult rainbow trout, the peak parasitaemia was reduced. These results indicate that MAb-001 is a protective monoclonal antibody and the antigen it recognizes is located on rhe surface membrane of C. salmositica. The antibody also inhibits multiplication and affects viability of the parasite under in vitro conditions.