SEPARATION AND CHARACTERIZATION OF ADULT WORM PROTEINS AND GLYCOPROTEINS FROM THE LIVER FLUKE OPISTHORCHIS-VIVERRINI

Detailed studies of liver fluke proteins and antigens are necessary to facilitate further investigation of the human immune responses to these parasites. Accordingly, Opisthorchis viverrini antigens were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. We initially encountered excessive background smearing, vertical streaking, and indistinct bands that were similar to problems previously described by investigators studying this and other trematodes including Schistosoma mansoni. These problems were especially evident with silver staining of proteins and occurred despite the extensive use of protease inhibitors. They were minimized by using mini (vs. large) SDS-PAGE and Coomassie blue protein staining. With the latter 2 techniques, adult worm somatic proteins and excretory-secretory products were separated and characterized. Immunoblots using rabbit anti-adult worm sera demonstrated that some of these proteins were antigens common to both the adult and metacercarial stages. Several of these antigens also corresponded (according to molecular weight) to glycoproteins, detected by concanavalin A blotting. These findings form a base for subsequent studies of the human immune response to liver fluke infection.