الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
Schistosomiasis is a tropical disease estimated to afflict about 200 million people world wide. The disease is caused by variou.9 species of blood flukes of t he genus Schistosoma, which as adults live and lay eggs in the veins of the intestines or bladdero Snail control and chemotherapy are t he main, but by methods of control 0 no means satisfactory Laboratory and field studies using attenuated schistosomes for vaccination trials, have shown that immun ization is an effective method for controlling this diseaseo However, the use of attenuated parasite vaccines for human immunization was considered to be impractical and potentially dangerous 0 The production of a defined non living vaccine was suggested to be preferable 0 The early att empt s to vaccinate us ing non-living parasite preparat ions against schistos omiasis had met wit h little success 0 However, when non-living parasite materials were used for vaccination under different experimental protocols it was shown that, the method of antigen presentation is crit ical for the product ion of protect ive Because, intrade~mal injection of parasite aaterials in conjunction wit h a bacterial adjuvant induced significant level of prot ect ion, whereas intravenous inj ect ion of the same combination did not induce prot ect iono lli the present study, a soluble worm antigen preparation (SWAP) prepared from adult ~ mansoni worms9 was used in conjunction with a bacterial adjuvant BCG(Bacillus Calmette Guerin) to vaccinate mice against ~ mansoni challenge infect ions 0 the intradermal rout e 0 The combination was injected using It was aimed to evaluate the protection induced by this combination and to study the effect of an anti-schistosomal drug (praziquantel) and an immunosuppressive drug (hydrocortisonE#, on ~ mansoni infection in vaccinated animals Cl The ~ mansoni parasit e (Delt a strain) was used throughout t he study 0 The intermediate host used was Biomphalaria alexandrina sna il 0 The animal host was the white albino mice of the High Institute of Public Health straino Eight groups of experimental animals were designed: was designed to test the validity of the commonly used procedure of assessing vaccine efficacy, namely determinat ion of adult worm count after a single challenge with cercariaeCl . Groups 2-6: were designed to test the effect of frequency of vaccine application, vaccine dose, time of challenge and number of challenging cercariae, on the level of protectiono Also, to test the relationship between humoral , antibody response and the level of protection induced by vaccinat iono . Group 7 was designed to test the effect of an ant ischistosomal drug (praziquantel) on S. mansoni infection in vaccinated animalso . Group 8 was designed to test the effect of an immunosuppressive drug (Hydrocortisone) on ~ mansoni infection in vaccinated animals 0 It was worthy to mention that, mice of groups 1, 2, 3. 4, 5, 7 and 8 were vaccinated with 200 ug SWAP+ 5 x 106 BCG colony forming units (CFU)/mouse~while mice of 6 group 6 were vaccinated wit h 1 mg SWAP + 5-x ~O BCG(CFU)/ mouse 0 Also mice of group 1 were challenged with male cercariae only, while mice ~f groups 2- 8 were challenged witb mixed sex cercariaeo Moreover, the vaccine induced immWlity was assessed by determination of adult worm count and by estimation of ,antibody level u~:dng the enzyae linked immunosorbent as say (ELlSA) in groups 1 to 6. - In groups 7 and 8 the adult worm count and the t issue egg count s in livers alld int.eJ3tines -were”det-ermined. The obtained results were summarized as follows: 1. There was no significant difference in worm burden between mice receiviM several trickle male cercarial cMllenges and those receiving a siMle cumulative total of the trickle challenges. 2. Intradermal vaccinat ion wit h SWAP + BCG, gave prot eet ion ag,:iinst challenging So mansoni cercariae (up to 60 reduction in adult worms)o 3. The dose of the vaccine affected the .level of protect ion, while the frequency of vaccine application, time of challenge a.n~ number of challenging cercariae had no or little effect 4- The humoral antibod>v response in vaccinated mice was higher than t hat of the cont rols, however, a relat ionship between the level of humoral antibodies and the level of protection, was lackingo 5- The adult worm count and t issue egg count (in liver and intestines) were lower in vaccinated treated mice than mice vaccinated or treat ed only. However, the difference was not statistically significant Cl ~. Hydrocortisone inj ect ion in a dose of 004 mg/mouse/ day for one week before challenge infection did not affect the adult worm count or tissue egg count in non vaccinated or vaccinated mice 0 It was concluded that, when a non-livin~ paras it e preparation (SWAP) was used in conjunction with a bacterial adjuvant (BCG), for intradermal vaccinat ion of mice against h manl’loni infection, a significant level of protection was inducedo The protection was found to depend more likely on the dose of the vaccine, rat her than to depend on the frequency of vaccine application, the time of chall enge or the number of challenging cercariaeo Also, the level of protection induced by vaccination did not show a significant change when multiple small challenges or a cumulative total challens:e were used. Moreover, there was no definite relationship between the level of protection produced and the humoral response despite the detection of higher antibody levels in vaccinated than in control animals Moreover, the combination of praziquantel and vaccination increased the effect - of vaccination or chemotherapy on ~ mansoni infection, however, this effect was not stat isticall,V significant 0 On the other hand, hydrocortisone injection did not alt er the protection induced by vaccin-ationo.^leng