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In the present work antigenization with somatic and metabolic antigens of adult Schistosoma mansoni worms, their cercariae or eggs has been tried. The study of the immunoglobulin patterns in infected and vaccinated non infected mice showed increase in IgG in all animals, increase in IgM only in the infected and IgA was frequently increased in mice that received metabolic or egg antigens. As regards the degree of resistance of vaccinated animals to S. mansoni infection, 2 groups gave prominent results. 1st the group vaccinated with Schistosoma mansonmetabolic worm antigen in which we got: -- Reduction in the worm load. -- Delayed ovulation and reduction in the number of ova/24 hr stools and/g of liver tissue. -- The histopathological picture of the liver was the best. 2nd the group vaccinated with egg antigen: Although it showed delayed ovulation and reduction in the ova count per 4 hr stools and/g liver tissue, yet the histopathological picture was the worst showing the largest granulomata.

A study has been done to find the effect of purification of crude antigens, extracted from adult Fasciola gigantica and Fasciola hepatica worms on the sensitivity of some serological techniques in diagnosis of fascioliasis. Using C.I.E.P. test, the partially purified antigens of both Fasciola species were less sensitive than their corresponding crude ones. Using I.H.A., the difference between results of crude and partially purified antigens for the two species were statistically insignificant, both (P greater than 0.05). So in applying this test, there is no need for the partially purification of antigen. On using E.L.I.S.A. the partially purified antigens showed higher sensitivities for detection of fascioliasis than their corresponding crude ones. Partially purified F. gigantica and F. hepatica antigens gave nearly the same results whether using C.I.E.P., I.H.A. or E.L.I.S.A. However, E.L.I.S.A. was the most sensitive technique followed by I.H.A. then C.I.E.P.

An enzyme-linked immunosorbent assay (ELISA) was evaluated for diagnosis of experimental or naturally occurring Fasciola sp. infections in cattle. The positive rate for the ELISA in calves inoculated with Fasciola metacercariae were 21.1% by 2 weeks postinoculation (PI), 94.6% by 4 weeks PI and 100% by 6-21 weeks PI. The positive rate for the immunodiffusion test (Ouchterlony test) reached 91.7% by 2 weeks PI, however, it dropped to 77.8% by 10 weeks PI. The positive rate for the fecal egg examination was 0% by 10 weeks PI, 77.8% by 12 weeks PI and 100% by 14-21 weeks PI. The practical application of ELISA was tested by using 165 cows raised under field condition. All the 24 cows that were positive both in the fecal egg examination and the Ouchterlony test were ELISA positive. Of the 6 cows that were egg positive and Ouchterlony negative, 5 showed ELISA positive reactions. Of the 27 cows that were egg negative and Ouchterlony positive, 24 were ELISA positive. Of the 108 cows that were egg negative and Ouchterlony negative, 90 were ELISA negative. However, the other 18 cows had ELISA positive reactions. Our results suggested that the ELISA using crude adult antigen was superior to the Ouchterlony test and fecal egg examination for diagnosis of experimental or naturally occurring Fasciola sp. infections in cattle.

The progression of humoral immune responses exhibited by mice during the year following exposure to Schistosoma mansoni cercariae was established by studying radioimmunoprecipitations of adult male and cercarial glycoproteins. 35S-methionine metabolically-labeled adult S. mansoni male worm glycoproteins precipitated by sera of 14 mice were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The initial specific antibody response (week 5) was directed against 3 worm glycoproteins of 55,000, 52,000 and 35,000 molecular weight (Mr). As infection progressed, all major worm glycoproteins (ranging from 400,000 to 12,000 Mr) were precipitated by sera from each mouse and only minor individual variations in titer were noted in the antibody responses of the mice against these glycoproteins. Maximal immunoreactivity toward the radiolabeled glycoproteins occurred at week 20 and remained at this level through week 50. Analogous experiments with sera from acutely- and chronically-infected humans resulted in immunoprecipitation patterns almost identical to those obtained with sera from the corresponding experimentally-infected mice. The kinetics of the antibody response against 125Iodine-labeled cercarial glycoproteins was the same as that observed with worm glycoproteins.

Partial purification of a saline extract of adult Fasciola gigantica by chromatography on Sephadex G200 gave four peaks, of which only the first two contained material which gave a precipitation reaction with sera from infected buffaloes. None of these gave false reactions with sera from uninfected animals but even the first and most sensitive fraction only reacted with 57.5 per cent of sera from animals known to be infected with moderate numbers of F gigantica.

The application of an enzyme immuno-assay is evaluated with regard to antibody reactivity to Opisthorchis viverrini antigen in 20 Laotian patients and control groups including patients with other helminthic infections as well as persons without parasitic infestation. It is concluded that the enzyme immuno-assay indicates infection by O. viverrini. In certain circumstances, which are discussed, the test may serve for valuation of treatment.

Five lambs were each sensitized with 400 metacercariae of Fasciola gigantica irradiated at 3 kr gamma rays. Eight weeks later, they were each challenged together with 5 controls with 500 non-irradiated metacercariae. Eight weeks later, all of the animals were necropsied and the worm burdens determined. The lambs which received the sensitizing infections had 80% less worms than the controls. The sensitized lambs also showed less hepatic damage compared with the controls as indicated by lower levels of the serum enzyme glutamate dehydrogenase. The blood indices showed insignificant reductions in the sensitized lambs whereas marked reductions were found in the erythrocytes, packed cell volume and haemoglobin values of the challenge controls. Bilirubinaemia was also evident in this latter group.

One or two mature primary infections with Fasciola gigantica which had been removed by anthelmintic treatment resulted in a significant reduction in the number of flukes recovered from challenge infection as compared with that from controls. Characteristic lesions of fascioliasis were seen in the livers of the 3 groups, however, goats with two primary abbreviated infections prior to challenge showed more severe lesions than those of animals with one primary abbreviated infection or those of challenge controls. The former group also showed the highest serum glutamate dehydrogenase and sorbitol dehydrogenase peaks following challenge infections and pulmonary fascioliasis was encountered in one of the goats of this group. Haemoglobin concentration and packed-cell volume decreased after infection in the three groups of goats.

Sensitisation of goats for eight weeks with metacercariae of Fasciola gigantica gamma-irradiated at 3 kr resulted in significant resistance to an homologous challenge with normal metacercariae. However, serum sorbitol dehydrogenase assay suggested that, whereas little damage was produced by immunising infections, considerable hepatic damage was caused by flukes remaining from challenge infections. On the other hand sensitisation with cercariae of Schistosoma bovis gamma-irradiated at 3 kr did not stimulate any resistance against heterologous challenge with F. gigantica.

The antibody response of six calves infected with 500 metacercariae of Fasciola gigantica each was monitored throughout 30 weeks of infection using an indirect fluorescent antibody technique (IFA). In vitro excysted F gigantica were employed as the test antigen. All animals showed high antibody titres from two to six weeks post-infection. Thereafter the antibody titres diminished gradually. Although all the experimentally infected animals harboured fluke burdens at autopsy, most gave negative IFA tests from 22 weeks post infection onwards. Specific immunofluorescent staining occurred on the surface glycocalyx of the newly excysted flukes. It is likely that this glycocalyx provides one of the earliest antigenic stimuli for the host's immune reactions to fascioliasis.

Using the local strains of Schistosoma bovis and Fasciola gigantica, it was shown that Sudanese zebu calves with mature primary infections of F. gigantica were highly resistant to challenge with S. bovis cercariae, and vice versa. Liver enzyme tests showed that, in both cases, the primary infections had caused some liver damage. Primary infection with irradiated S. bovis cercariae, which did not cause significant liver damage, did not protect significantly against challenge with F. gigantica.

Four lyophilizated liver flüke antigens and one of hydatid fluid were examined for the presence of blood group like antigens P1, A, B, M and N by an hemagglutination inhibition test with hyperimmune and natural hemagglutinating sera. P1 or P1-like substance was found in the extracts of "Fasciola hepatica" and "F. gigantica" in a lower concentration than in echinoccocal fluid. This presence may explain the occurrence of anti-P1 antibodies in patients infected with liver flüke and belonging to the P2 blood group. However biochemical studies will be necessary to determine if the P1 activity is due to the blood group P1 substance of the red cell itself or due to a P1 like substance.

The partially purified extract of Fasciola gigantica was incubated with enzyme pepsin and samples were taken at different time intervals from 0-24 hours, and tested intradermally for diagnosing bilharziasis. The enzymatic degradation of the protein molecule results in the progressive decrease and eventually the complete disappearance of serological activity. This showed that the protein portion of the antigen was deemed necessary for its activity in intradermal tests for diagnosing schistosomiasis. Amylase, even at a concentration of 5 per cent, did not influence the activity of the partially purified extract of Fasciola gigantica. This showed that the carbohydrate portion of the antigen has no effect on serological activity. The partially purified extract of Fasciola gigantica was subjected to heating at 37 degrees C, 50 degrees C, and 60 degrees C for periods of two, six and 24 hours, and tested intradermally for diagnosing schistosomiasis. Heating decreased the reactivity of the supernatant liquid of the protein solution but did not completely inactivate the serologically active component which is fairly stable at 50 degrees C. Temperatures higher than 50 degrees C started to affect the serological activity of the protein solution. The higher the temperature, the shorter is the time required for the inactivation of the protein. This shows that the serologically active component is protein and not polysaccharide which resists much higher temperatures.