STUDIES OF THE PKX PARASITE IN RAINBOW-TROUT VIA IMMUNOHISTOCHEMISTRYAND IMMUNOGOLD ELECTRON-MICROSCOPY

Tissues from rainbow trout Oncorhynchus mykiss that had been exposed t o proliferative kidney disease (PKD) infective waters were sampled fro m May through to August. These tissues were examined via immunohistoch emistry with four monoclonal antibodies (MAbs) previously raised to th e causative agent of PKD, a myxosporean termed PKX. The results showed the MAbs were specific for different phases in the parasite's life cy cle. Immunogold electron microscopy revealed that three of the MAbs ap peared to be specific for vacuoles within the extrasporogonic parasite s, and the fourth MAb was specific for secondary cells within the extr asporogonic parasite and for sporogonic stages. Intensification of the staining properties of the parasite through its maturation in the kid ney, as demonstrated by immunohistochemistry, indicates that the extra sporogonic parasite may undergo autophagy during the release of maturi ng secondary cells.