Dr. Kassai Tibor - Dr. Murai Éva szerk.: Parasitologia Hungarica 10. (Budapest, 1977)

Parasit. Hung 10. 1977. Ligula intestinalis (L., 1758): Investigation on Plerocercoids and Aduits for Protease and Protease Inhibitor Activities Dr. István MATSKÁSI — Dr. Sándor JUHÁSZ Research Institute for Veterinary Science, Hungarian Academy of Sciences, Budapest "Ligula intestinalis (L. , 1785): investigation on plerocercoids and adults for protease and protease inhibitor activities" - Matskási, I.

, Juhász, S. - Parasit. Hung. 10^ 51-60. 1977. ABSTRACT. Whole worm extracts prepared from homogenates of plerocercoids and adult specimens of the cestode Ligula intestinalis were found to contain a chymotrypsin-like proteolytic enzyme as well as inhibitors acting against mammalian pancreatic trypsin and chymotrypsin. Proteolytic enzyme activity and protease inhibitors could also be demonstrated in culture media of in vitro maintained parasites. Many enzymes functioning in the uptake and digestion of nutriments in animals lacking a digestive tract were detected histochemically in the integument of tapeworms (TAYLOR and THOMAS, 1968; READ, 1973). However, the occurrence and function of proteolytic enzymes within this range was long disputed, partly because of the unreliability of methodical approach, partly because of the apparent irreconciliability of protease function with the known aspects of tapeworm nutrition (von BRAND, 1973). Recently, however, proteolytic activity was demonstrated by various, chiefly natural substrates in larval and adult specimens of several tapeworm species (KWA, 1972; DUBOVSKAYA, 1973; SHISHOVAKASATOCHKINA and DUBOVSKAYA, 1976). Production and secretion of proteolytic enzyme inhibitors by tapeworms was implied by REICHENBACH-KLINKE (1970) on the grounds that living specimens of the fish tapeworm Pro- teocephalus longicollis and the extract prepared from these parasites decreased the intestinal tryptic activity of the host. Inactivation was attributed to inhibitors produced and secreted by the parasites without pursuing evidence of their actual presence. PAPPAS and READ (1972a) found in in vitro studies of Hymenolepis diminuta that the decrease of tryptic activity occurred during incubation of tapeworms in trypsin-containing nutrient medium and presented evidence that the reduction of enzyme activity was unrelated to either fdsorption or absorption. Similar results were obtained on incubation of intact, live Hymenolepis diminuta specimens in a chymotrypsin-containing medium (PAPPAS and READ, 1972b). This paper is a report on studies of the proteolytic enzyme activity and inhibitor production of Ligula intestinalis

. The two antagonistic effects were studied simultaneously in extracts of the same parasite specimens, or during in vitro incubation in nutrient medium. Material and Method Plerocercoid larvae of L. intestinalis and adult specimens obtained either from experimentally infected ducks or by in vitro culturing were used. Plerocercoids were secured from naturally infected breams (Abramis brama) freshly taken from the Lake Balaton. Larvae in identical stage of development were washed in five changes of sterile 0. 65% NaCl solution after determination of wet weight and length. In the first series of experiments washed larvae were placed in sterile Tyrode, Krebs-Ringer-Tris (KRT, pH 7.4), Tris-sucrose (TS, pH 7.5), TC 135 (Difco) or TC 199 (Difco) medium of tenfold volume related to body weight, containing in each ml 2000 IU penicillin, 1 jig