Excretory-secretory products of Echinostoma paraensei sporocysts mediate interference with Biomphalaria glabrata hemocyte functions.
Miracidia of Echinostoma paraensei were cultured in medium containing 14C-labeled amino acids, allowed to transform into sporocysts, and their excretory/secretory products (E-S) were collected and characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis and autoradiography. Effects of E-S on hemocytes of Biomphalaria glabrata were also assessed. E-S collected during day 1 of culture (E-S1) contained several polypeptides, none of which were labeled, suggesting that E-S1 are largely preformed. E-S1 significantly depressed the ability of hemocytes to phagocytose sheep red blood cells (SRBC), but otherwise had little effect on hemocyte structure or behavior. E-S released by sporocysts in day-2 cultures (E-S2) and in older cultures generally were similar and also contained several polypeptides, many of which were labeled, indicating active synthesis of E-S in vitro. E-S2 strongly inhibited hemocyte uptake of SRBC. Also, hemocytes pretreated with E-S2 assumed a spherical shape and failed to spread normally. E-S obtained through 10 days of culture mediated this effect. Active components of E-S2 were greater than 100 kDa in their native configuration, were heat- and trypsin-labile, and were bound by anti-E-S antibodies. Both greater than 200- and 80-kDa bands were prominent in anti-E-S immunoprecipitates. Hemocytes derived from snails of the 13-16-R1 strain of B. glabrata (a strain resistant to infection with Schistosoma mansoni), when pretreated with E-S2, bound to sporocysts of S. mansoni but lost their ability to damage such sporocysts. E-S2 interfered with hemocyte functions in ways inferred from earlier classic in vivo studies of trematode-snail interactions.
Loker
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Department of Biology, University of New Mexico, Albuquerque 87131.
Cimino
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Hertel
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D000818:Animals; D001345:Autoradiography; D001700:Biomphalaria / Q000276:immunology / Q000469:parasitology / Q000502:physiology*; D002448:Cell Adhesion; D003470:Culture Media; D004449:Echinostoma / Q000502:physiology*; D004591:Electrophoresis, Polyacrylamide Gel; D015801:Helminth Proteins / Q000378:metabolism*; D006434:Hemocytes / Q000276:immunology / Q000469:parasitology / Q000502:physiology*; D006358:Hot Temperature; D008854:Microscopy, Electron; D010587:Phagocytosis; D012550:Schistosoma mansoni / Q000502:physiology; D014357:Trypsin / Q000494:pharmacology
D003470:Culture Media; D015801:Helminth Proteins; D014357:Trypsin