Surface Of Adult Schistosoma Mansoni Research Articles

The outer bilayer of the adult schistosome tegument surface has a low turnover rate in vitro and in vivo

An immunoradiometric assay has been used to determine the rate of loss of host erythrocyte antigen from the tegumental surface of adult Schistosoma mansoni. Host antigens were lost from the parasite surface with a half-time of up to 45 h during chase incubation in vitro, and with a half-time of about 5 days during residence in vivo in naive recipient hamsters. Since the host antigens were associated intimately with the outer bilayer of the tegument surface, it is suggested that the rate of surface turnover may similarly be very low. The implications of these findings for immune evasion by the adult parasite are discussed.

Identification of exposed components on the surface of adult Schistosoma mansoni by lactoperoxidase-catalysed iodination

Adult schistosomes have been labelled with 125I using the lactoperoxidase-catalysed technique modified to cause minimal worm damage. After surface membrane removal and characterization, at least 13 labelled proteins were identified together with a large amount of labelled glycolipids, free fatty acids and phospholipids, especially phosphatidyl ethanolamine. Cationised ferritin has been used to stimulate surface membrane turnover of iodinated worms and the shedding of covalently bound 125I-counts used as an index of turnover. Finally worms have been iodinated before and after stimulation of membrane turnover in chemically defined media and the patterns of labelled proteins were compared.

Schistosoma mansoni: dose-related tegumental surface changes after in vivo treatment with praziquantel.

The in vivo effects of a range of concentrations of praziquantel (10, 25, 50, 100, 200 and 500 mg/kg body weight of mouse) on the tegumental surface of adult Schistosoma mansoni were studied using scanning electron microscopy. Worms were recovered from mice at 1 and 4 h post-treatment. In general, irrespective of the dose level, male worms exhibited more pronounced and extensive surface alterations which included surface bleeding, swellings, wrinkling and constrictions and surface lesions, particularly on the spined tubercles. In male worms, in particular, the number of worms exhibiting damage and the amount of tegumental surface damage depended, mainly, on the concentration of praziquantel, although, at any given dose level, the extent of the damage increased with time post-treatment.

Schistosoma mansoni: Tegumental surface alterations induced by subcurative doses of the schistosomicide amoscanate

Effects of the administration of a single subcurative dose of a schistosomicidal compound, amoscanate (CGP 4540), on the tegumental surface of adult Schistosoma mansoni were studied using scanning electron microscopy. Worms were recovered from mice between 1 hr and 102 days after treatment. Surface alterations included pronounced swelling, wrinkling and constriction, collapse of sensory bulbs, erosion of large areas of the surface, and attachment of host cells. Different types of lesions of different degrees of intensity were found among worms from the same individual host. Partial and, more rarely, complete repair was noted 62 days after treatment, but even after 102 days not all the lesions had been fully repaired.

Characterization and Isolation of Concanavalin a Binding Sites from the Epidermis of S. mansoni

Using concanavalin A labeled with tritium and fluorescein isothiocyanate we studied the binding properties of this plant lectin to adult paired schistosomes. Using concanavalin A coupled to a sepharose column we attempted to isolate and characterize concanavalin A binding molecules from the epidermis of adult schistosomes. Our results indicate the presence of specific concanavalin A binding sites on the surface of adult Schistosoma mansoni. A significant percentage of the concanavalin A was specifically bound and showed characteristics similar to that identical in other concanavalin A binding tissues. The parasite's concanavalin A binding sites appear to be 2 or 3 high molecular weight glycoproteins. There is some indication that glycoproteins associated with the worm's epidermis function as enzyme(s). The immunological significance of these glycoproteins has not been determined.

Schistosoma mansoni: Adsorption of Human Blood Group A and B Antigens by Schistosomula

Immediately following skin penetration, schistosomula of Schistosoma mansoni were found capable of passively adsorbing human A and B blood group antigens onto their surfaces. The antigens were adsorbed from intact erythrocytes, boiled human saliva, or alcohol extracts of erythrocyte membranes. Evidence is presented suggesting that a glycosphingolipid structure may be important in the binding of erythrocyte antigens to schistosomes. No uptake of various other blood group antigens could be demonstrated. Mouse erythrocyte antigens have been demonstrated on the surface of adult Schistosoma mansoni reared in mice (Smithers, Terry, and Hockley, 1969; Clegg, Smithers, and Terry, 1971a), and it has been shown that at least one such antigen is passively adsorbed by schistosomula (Dean, 1971; Sell and Dean, 1972; Dean and Sell, 1972). Clegg, Smithers, and Terry (1971b) reported that young schistosomes reared in a culture medium containing human erythrocytes were destroyed following surgical transfer into monkeys which had been immunized against human erythrocytes, indicating that human antigens are also acquired by schistosomes. In one experiment, the erythrocytes used to immunize recipient monkeys differed from the erythrocytes in the worm cultures with respect to five major blood group antigens. Fewer worms were killed upon transfer to monkeys so immunized than was the case with homologous transfers, and this led the authors to conclude that blood group antigens might be acquired by schistosomula. The present study was carried out to deReceived for publication 13 September 1973. * Supported by the Bureau of Medicine and Surgery Work Unit No. MR041.05.01.0023A6GI. The opinions or assertions contained herein are the private ones of the author and are not to be construed as official or reflecting the views of the Navy Department or the naval service at large. The experiments reported herein were conducted according to the principles outlined in the Animal Welfare Act (PL 89-544 as amended) and followed the guidelines prescribed in DHEW Publication No. (NIH) 72-23, formerly PHS Publication No. 1024, Guide for Laboratory Animal Facilities and Care. termine which, if any, human blood group antigens are adsorbed onto the surfaces of schistosomula in vitro. MATERIALS AND METHODS Schistosomula were prepared from Puerto Ricanstrain cercariae of S. mansoni by allowing them to penetrate excised rat skins into Hanks' Balanced Salt Solution (HBSS), by methods described previously (Stirewalt and Uy, 1969; Clegg and Smithers, 1972). Alcohol extracts of erythrocyte membranes were prepared by the method of Koscielak (1963). Wet membranes prepared by hypotonic lysis (Dodge, Mitchell, and Hanahan, 1963) were mixed with ethanol to a final alcohol concentration of 85%, mixed on a shaker at room temperature for 3 days, centrifuged, and the superatant fluid stored at -15 C for 3 days. The resulting precipitate was collected by centrifugation and stored at -70 C. Koscielak showed that the blood group active molecules in these preparations are glycosphingolipids. Saliva of a known secretor of soluble blood group A substance was boiled and centrifuged, and the supernatant fluid employed in appropriate experiments. Neutr AB is a commercial preparation (Dade Reagents, Miami, Florida) containing both A and B blood group activities. The source of this preparation (equine gastric mucin) and the method of preparation (Dade Reagents, pers. comm.) indicate that the active molecules are probably glycoproteins rather than glycosphingolipids (Baer, Kabat, and Knaub, 1950; Kabat, 1956). Specific activities of alcohol-extracted antigens and Neutr AB were measured by means of the hemagglutination inhibition (HI) assay. Serial double dilutions of antigen were prepared in Vbottom wells of Microtiter plates (Cooke Engineering Company, Alexandria, Virginia). Dilutions were made in pH 7.4 phosphate-buffered saline (PBS) at a final volume of 0.05 ml per well. An equal volume of blood group typing antiserum