الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
In this study, the feasibility of using a nucleic acid vaccine encoding the circulating cathodic antigens (CCA) of S. mansoni to induce antipathological and protective immune responses was evaluated. The immunological, immunohistochemical and pathological changes of the host were tested in order to determine which group would show the best anti¬pathological effect induced by the vaccine. C57BL/6 mice weighing (20¬30 g) had received three doses of the plasmid DNA (pDNA). The mice were randomly divided into 4 groups: the first; wild (control) group where the animals were immunized with empty plasmids DNA. The second; Full group where the animals were immunized with plasmids DNA with a full¬length insert of (CCA) gene. The third group; Eco group where the animals were immunized with plasmid DNA with an insert of the CCA gene previously cut with the EcoRI. The last group; B/X group where the animals were immunized with plasmid DNA with an insert of the CCA gene previously cut with BamHI & XemaI, All groups were challenged with cercariae 4 weeks after the last dose. Sera were collected at two different time points (6 and 9 week after infection).The results showed that vaccination with CCA encoding plasmid DNA (pDNA) elicited IgG and IgM isotypes. The presence of these isotypes was confirmed by ELISA.To evaluate the efficiency of using CCA encoding plasmids as antipatological vaccine for schistosomiasis different parameters have been tested and these parameters were; histopathological examination of liver sections stained with haematoxylin and eosin, oogram changes as revealed by examination of fragments of the small intestine for the developmental stages of the eggs. Meantime, the number of ova per gram of intestinal tissue, as well as the levels of IgG and IgM were evaluated. In all cases.