Humoral immune response of turbot, Scophthalmus maximus (L.), to antigens from Tetramicra brevifilum Matthews & Matthews, 1980 (Microspora) |
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| Authors: | J LEIRO J ESTÉVEZ M T SANTAMARINA M L SANMARTÍN F M UBEIRA |
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| Institution: | Departmento de Microbiología y Parasitología, Universidad de Santiago de Compostela, Spain |
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| Abstract: | Abstract. The humoral immune response of turbot, Scophthalmus maximus (L.), to antigens from the microsporean parasite Tetramicra brevifilum Matthews & Matthews, 1980, was studied. Thirty days after intraperitoneal immunization with whole T. brevifilum spores in Freund's complete adjuvant, double indirect ELISA indicated that initial production of antibodies to parasite surface antigens was considerably higher than production of antibodies to the antigens contained in a crude extract (CE) of spores. Following re-immunization without adjuvant on day 30, levels of antibodies to surface antigens gradually declined, whilst levels of antibodies to CE antigens increased. The antibody response of intraperitoneally immunized fish was characterized by Western blotting of total soluble antigens obtained by heating and reduction of T. brevifilum spores at 95–100°C in Tris-HCl buffer containing SDS and dithiothreitol: a series of bands with molecular weights between 20 and 53 kDa was recognized by immunized turbot sera. Four additional bands (with molecular weights between 15 and 18kdA) were recognized by serum from re-immunized fish. ELISA studies of sera from naturally infected fish revealed a surprisingly low incidence of strong T. brevifilum seropositivity (61% individuals); antibodies to surface antigens predominated in seropositive individuals. The low background response levels and high sensitivity of the ELISA used in this study indicate that the assay is of value for the monitoring of serum antibody levels in turbot. However, given the relatively low seropositivities observed in naturally infected turbot, particularly to CE antigens, the use of anti- T. brevifilum serum antibody levels for the diagnosis of infection by this parasite may lead to false negative results. |
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