Previous workers at Cultus Lake discovered a new species of Schistosome cercaria. In the present attempts to find this cercaria and to elucidate its life cycle, four completely different dermatitis-producing forms were discovered, two of which are considered new species. The other two may be new. Three of the cercariae are described in detail. These are the cercaria of Trichobilharzia adamsi n.sp., Cercaria chilliwackensis n.sp. and Cercaria 10 which may be a new species. The description includes morphology, behavior, snail hosts, dermatitis-producing ability, and observations on the sporocysts of these forms. All were found to be capable of producing Schistosome dermatitis. Therefore two and possibly three more cercariae have been added to the list of known dermatitis-producers. The three cercariae were found in specific areas along the north-west shoreline of Cultus Lake. Attempts were made to complete the life cycle of the three cercariae. Two approaches were adopted. Animals were trapped within the areas at which the cercariae were found, but examination showed that they did not possess adult Schistosomes. Laboratory experiments were carried out in which animals were subjected to the various cercariae and later examined for adult worms. An immature female worm was recovered from a domestic duck which had been exposed to cercariae. The worm, Trichobilharzia adamsi, is described as a new species. Part of the life cycle of this trematode is described. The domestic duck was established as a definitive host under experimental conditions. The specific definitive host of the trematode at Cultus Lake was not determined. The cercaria of T. adamsi is placed in the "ocellata group" on the basis of its morphology. Cercaria chilliwackensis is placed along with Cercaria douthitti in the "douthitti group". Cercaria 10 is very similar to the cercaria of Gigantobilharzia huronensis, and is placed with the latter in the "spindalis group". All three of the cercariae described possess papillar spination. These spines have been described only once in the past as occuring on a dermatitis-producing cercaria. The papillar supination is described in detail. The spines are located in similar patterns on the bodies of the three cercariae. This pattern is carried through to the adult of T. adamsi. Evidence is given of the occurance of papillar spination on cercariae elsewhere in the Province. A modification of the perfusion technique of Yolles et al is described. This was used for the investigation of the experimental animals for adult worms. Further, a new technique using the side-arm flask of McMullen and Beaver is described. The apparatus concentrates Schistosome cercariae in large numbers in a relatively small area. / Science, Faculty of / Zoology, Department of / Graduate

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Schistosomiasis is one of the most widespread parasite diseases in the world, whereas Schistosoma mansoni is a major schistosome species in Africa, America, and the Caribbean islets. Many antigenic vaccine candidates have been postulated, including sm22.6 and GST. Although the lower level of re-infection of human schistosomiasis is related to the higher level of IgE against rsm22.6, unfortunately, the observation of the experimental vaccination in mice finds some difficulties in further development of vaccine. In addition, the biochemical and biophysical properties of the antigen are virtually unknown, thus the present study intends to characterize sm22.6 from biochemistry and cell biology. To do this, sm22.6 was expressed in E. coli (BL21DE3) and purified to homogeneity. Analyses of the recombinant protein showed that the antigen was highly hydrophobic and formed polymers readily as judged by both native and denatured electrophoreses. Because various technologies including NMR and DNA binding which had been applied to the study of the antigen generated vague results, we decided to express the antigen in human breast cancer cell (MDA-MB-435s) to locate in the subcellular compartments where the antigen is situated. Results showed that the antigen, not like the recombinant expressed in E. coli, located in both cellular fluids and membrane, suggesting that the antigen might not be a skeleton protein as predicted by proteomics.

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This thesis focuses on humoral immune response of specific hosts to antigens of various developmental stages of bird schistosomes T. regenti and T. szidati, and follows up on previous research of antibody response in non-specific hosts (mouse, human). Sera of experimentally infected and hunted-down wild ducks were examined using the ELISA and western blot methods. The sera samples were taken in predefined intervals. Results of the ELISA analysis show the process of humoral immune response after infection by bird schistosomes. The level of specific antibodies IgY against homogenate of T. regenti cercariae increased significantly 20 d.p.i. in ducks infected by T. regenti. Such reaction wasn't observed in ducks infected by T. szidati. Slight changes in level of specific antibodies IgM against T. szidati cercariae homogenate were observed 10 d.p.i. only in fully immunocompetent ducks and in reinfected ducks. Examination of hunted-down wild ducks didn't prove infection by bird schisosomes; this conclusion was confirmed by results of the ELISA analysis. IgY antibodies from ducks infected by T. regenti demonstrated strong reactions with 2 antigens in ranges 49-47 kDa and 47-45 kDa. Other reactions, which were recognized, have not been observed in all specimen. An Western blott with homogenate from 7 days...

(English): Trichobilharzia regenti is a neurotropic parasite of birds from the family Schistosomatidae. Cercariae, the invasive stages of these trematodes actively penetrate the host skin employing excretory- secretory products (ESPs), which contain proteolytic enzymes able to disrupt host tissues and thus reach the successful transmission. The most abundant secreted enzyme responsible for cercarial penetration of the human schistosome S. mansoni is a cercarial elastase. This serine peptidase is well known for the degradation of skin proteins such as elastin, keratin, collagen or laminin. However, the active expression of the orthologue of this enzyme has never been found in the genus Trichobilharzia. For this reason, it was firmly believed, that cercaria of T. regenti uses mainly cysteine peptidases for the invasion of the host, particularly cathepsins, which were repeatedly identified in this life stage. To strengthen this hypothesis, we incubated T. regenti cercariae in the apparatus with the excised duck skin stimulating the release of their glands' content. The collected ESPs were further analysed by shotgun mass-spectrometry and for the first time, the protein form of cercarial elastase was identified. Unfortunately, we failed to produce its active recombinant protein in yeast and bacterial...