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Topographical Alterations and Increased Antigenic Exposure at the Outer Tegumental Surface of Schistosoma mansoni Adult Worms as a Consequence of Praziquantel Treatment and UV-irradiation (in vitro).

1[]Gad HS, 1Hafez MN and 2Maghraby AS.

1National Center for Radiation Research & Technology and 2National Research Center, Cairo, Egypt.

Schistosoma mansoni adult worms harvested from Swiss albino mice infected with 200 cercariae/mouse, seven weeks post infection was subjected to UV-irradiation and praziquantel (PZQ) treatment. Treated worms were processed for scanning electron microscopy, light microscopy and immunofluorescence technique. Results demonstrated that in vitro PZQ-treatment or UV-irradiation induced severe surface tegumental damage, disruption, and corrugation of tubercle spaces. Regression of spines from the dorsal surface of the tegument was also observed. A variety of histological changes have been observed post in vitro PZQ-treatment in the structure of the tegumental and subtegumental tissues. Focal surface swelling and erosion together with marked loss of spines from the tegumental tubercles were observed in addition to slight vaculation in subtegumental tissues. The extent of tegumental damage was apparent and severe in PZQ-treatment rather than UV-irradiation, which showed relatively moderate damage. In the immunofluorescence assay treated and non-treated control worms were probed with infected mouse serum, and incubated with conjugated (FITC) anti mouse IgG monoclonal antibody. An intensive fluorescent reaction was observed at the tegumental surface of worms pre-treated with praziquantel. Relatively moderate reaction was observed with UV-irradiated worms. Non-treated control worms showed mild positive reaction . This indicates an increase in the exposure of antigenic epitopes at the tegument of the treated worms than non-treated control worms. It is concluded that the induced damage in the tegumental surface and the exposure of antigenic epitopes as consequence of either PZQ-treatment or UV-irradiation could play a central and essential role in the propagation of the host-dependent effector immune mechanism(s) which lead to the death and elimination of adult PZQ-treated or UV-irradiated worms in infected hosts.

[] Corresponding Author: Hesham SM Gad. Address : National Center for Radiation Reasearch & Technology (NCRRT), Nasr City. Fax: 2749298. Residence Phone: 516178.