CHARACTERIZATION OF A MONOCLONAL-ANTIBODY AGAINST THE 47-KDA ANTIGEN OF CRYPTOBIA-SALMOSTICA KATZ AND ITS USE IN AN ANTIGEN CAPTURE ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR DETECTION OF PARASITE ANTIGEN IN INFECTED RAINBOW-TROUT, ONCORHYNCHUS-MYKISS (WALBAUM)
Ck. Verity et Ptk. Woo, CHARACTERIZATION OF A MONOCLONAL-ANTIBODY AGAINST THE 47-KDA ANTIGEN OF CRYPTOBIA-SALMOSTICA KATZ AND ITS USE IN AN ANTIGEN CAPTURE ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR DETECTION OF PARASITE ANTIGEN IN INFECTED RAINBOW-TROUT, ONCORHYNCHUS-MYKISS (WALBAUM), Journal of fish diseases, 19(1), 1996, pp. 91-109
A monoclonal antibody (designated MAb-007) was produced against the pa
thogenic haemoflagellate Cryptobia salmositica Katz. This IgG3 antibod
y recognized the 47-kDa antigenic polypeptide of C. salmositica (SDS-P
AGE and Western immunoblotting). The antibody did not agglutinate live
parasites, and there was no change in the staining intensity of the 4
7-kDa band on Western immunoblots after immunoabsorption of MAb-007 wi
th live intact parasites. The 47-kDa antigen recognized by MAb-007 was
localized in the cytoplasm of the parasite (immunogold labelling and
electron microscopy). The monoclonal antibody crossreacted with the 47
-kDa polypeptides of C. bullocki Strout and C. catostomi Bower & Woo.
It was used in an antigen-capture ELISA for the detection of parasite
antigen in the plasma of rainbow trout inoculated with the parasite, o
r with an attenuated vaccine strain of C. salmositica. All pre-infecti
on plasma were negative while all infected fish with detectable parasi
taemias were positive for antigen at 1-9 weeks after infection. Parasi
te antigen was even detected in vaccinated fish that were negative for
parasites using the wet mount microscopic technique. The antigen-capt
ure ELISA detected C. salmositica antigen in whole cell lysate prepara
tions at concentrations as low as 0 . 5 mu g ml(-1). Fifty microlitres
of fish plasma was required in the antigen-capture ELISA, and the use
of a plate reader and 96-well plates facilitated rapid analysis of a
large number of plasma samples. The sensitivity of the assay makes it
a potentially useful tool for detection of Cryptobia infections.