Trematodes of the order Diplostomida are well known as serious pathogens of man, and both farm and wild animals; members of the genus Schistosoma (Schistosomatidae) are responsible for human schistosomosis (schistosomiasis) affecting more than 200 million people in tropical and subtropical countries, and infections of mammals and birds by animal schistosomes are of great veterinary importance. The order Diplostomida is also rich in species parasitizing other major taxa of vertebrates. The "Aporocotylidae" sensu lato are pathogenic in fish, "Spirorchiidae" sensu lato in reptiles. All these flukes have two-host life cycles, with asexually reproducing larvae usually in mollusks and occasionally in annelids, and adults usually live in the blood vessels of their vertebrate hosts. Pathology is frequently associated with inflammatory reactions to eggs trapped in various tissues/organs. On the other hand, the representatives of Diplostomidae and Strigeidae have three- or four-host life cycles in which vertebrates often serve not only as definitive but also as intermediate or paratenic hosts. Pathology is usually associated with migration of metacercariae and mesocercariae within the host tissues. The impact of these trematode infections on both farm and wild animals may be significant.

• Klíčová slova
• Aporocotylidae, Blood flukes, Diplostomidae, Sanguinicolidae, Schistosoma, Schistosomatidae, Skin penetration, Spirorchiidae, Strigeidae, Trematodes,
• MeSH
• infekce červy třídy Trematoda * parazitologie   veterinární   MeSH
• interakce hostitele a parazita MeSH
• lidé MeSH
• Schistosomatidae genetika   MeSH
• stadia vývoje MeSH
• Trematoda fyziologie   patogenita   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

No effective method has yet been developed to prevent the threat posed by the emerging disease-cercarial dermatitis (swimmer's itch), caused by infective cercariae of bird schistosomes (Digenea: Schistosomatidae). In our previous studies, the New Zealand mud snail-Potamopyrgus antipodarum (Gray, 1853; Gastropoda, Tateidae)-was used as a barrier between the miracidia of Trichobilharzia regenti and the target snails Radix balthica. Since the presence of non-indigenous snails reduced the parasite prevalence under laboratory conditions, we posed three new research questions: (1) Do bird schistosomes show totally perfect efficacy for chemotactic swimming behavior? (2) Do the larvae respond to substances emitted by incompatible snail species? (3) Do the excretory-secretory products of incompatible snail species interfere with the search for a compatible snail host? The experiments were carried out in choice-chambers for the miracidia of T. regenti and T. szidati. The arms of the chambers, depending on the variant, were filled with water conditioned by P. antipodarum, water conditioned by lymnaeid hosts, and dechlorinated tap water. Miracidia of both bird schistosome species chose more frequently the water conditioned by snails-including the water conditioned by the incompatible lymnaeid host and the alien species, P. antipodarum. However, species-specific differences were noticed in the behavior of miracidia. T. regenti remained more often inside the base arm rather than in the arm filled with water conditioned by P. antipodarum or the control arm. T. szidati, however, usually left the base arm and moved to the arm filled with water conditioned by P. antipodarum. In conclusion, the non-host snail excretory-secretory products may interfere with the snail host-finding behavior of bird schistosome miracidia and therefore they may reduce the risk of swimmer's itch.

• Klíčová slova
• Chemo-orientation, Lymnaeid hosts, Miracidia, Potamopyrgus antipodarum, Trichobilharzia spp.,
• Publikační typ
• časopisecké články MeSH

Schistosomula (the post-infective stages) of the neurotropic schistosome Trichobilharzia regenti possess multiple isoforms of cathepsin B1 peptidase (TrCB1.1-TrCB1.6) with involvement in nutrient digestion. The comparison of substrate preferences of TrCB1.1 and TrCB1.4 showed that TrCB1.4 had a very narrow substrate specificity and after processing it was less effective toward protein substrates when compared to TrCB1.1. Self-processing of both isoforms could be facilitated by sulfated polysaccharides due to a specific binding motif in the pro-sequence. Trans-activation by heterologous enzymes was also successfully employed. Expression profiling revealed a high level of transcription of genes encoding the enzymatically inactive paralogs TrCB1.5 and TrCB1.6. The transcription level of TrCB1.6 was comparable with that of TrCB1.1 and TrCB1.2, the most abundant active isoforms. Recombinant TrCB1.6wt, a wild type paralog with a Cys29-to-Gly substitution in the active site that renders the enzyme inactive, was processed by the active TrCB1 forms and by an asparaginyl endopeptidase. Although TrCB1.6wt lacked hydrolytic activity, endopeptidase, but not dipeptidase, activity could be restored by mutating Gly29 to Cys29. The lack of exopeptidase activity may be due to other mutations, such as His110-to-Asn in the occluding loop and Asp224-to-Gly in the main body of the mature TrCB1.6, which do not occur in the active isoforms TrCB1.1 and TrCB1.4 with exopeptidase activity. The catalytically active enzymes and the inactive TrCB1.6 paralog formed complexes with chicken cystatin, thus supporting experimentally the hypothesis that inactive paralogs could potentially regulate the activity of the active forms or protect them from being inhibited by host inhibitors. The effect on cell viability and nitric oxide production by selected immune cells observed for TrCB1.1 was not confirmed for TrCB1.6. We show here that the active isoforms of TrCB1 have different affinities for peptide substrates thereby facilitating diversity in protein-derived nutrition for the parasite. The inactive paralogs are unexpectedly highly expressed and one of them retains the ability to bind cystatins, likely due to specific mutations in the occluding loop and the enzyme body. This suggests a role in sequestration of inhibitors and protection of active cysteine peptidases.

• Klíčová slova
• cathepsin B, cystatin, helminth, occluding loop, peptidase, processing, schistosome, substrate specificity,
• MeSH
• astrocyty metabolismus   MeSH
• cystatiny metabolismus   MeSH
• hydrolýza MeSH
• izoenzymy metabolismus   MeSH
• kathepsin B chemie   genetika   metabolismus   MeSH
• makrofágy metabolismus   MeSH
• myši MeSH
• oxid dusnatý metabolismus   MeSH
• prekurzory enzymů metabolismus   MeSH
• proteolýza MeSH
• RAW 264.7 buňky MeSH
• rekombinantní proteiny metabolismus   MeSH
• Schistosomatidae enzymologie   patogenita   MeSH
• substituce aminokyselin MeSH
• substrátová specifita MeSH
• vazba proteinů MeSH
• viabilita buněk MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• cystatin, egg-white MeSH Prohlížeč
• cystatiny MeSH
• izoenzymy MeSH
• kathepsin B MeSH
• oxid dusnatý MeSH
• prekurzory enzymů MeSH
• rekombinantní proteiny MeSH

Cercarial dermatitis (CD) is an allergic skin disease that rises in consequence of infection by invasive stages (cercariae) of trematodes of the family Schistosomatidae. CD has been considered a re-emerging disease, human cases have been reported from all continents, and tourism-threatening outbreaks occur even in frequented recreational areas. Although the symptoms of CD are generally known, the data on immune response in human patients are sporadic and incomprehensive. In the present study, we attempted to correlate the symptoms, personal history, and time course of CD in human patients with differential cell counts, dynamics of selected cytokines, and dynamics and quality of antibody response. By a systematic follow-up, we obtained a uniquely complex dataset from ten persons accidentally and concurrently infected by the same parasite species in the same locality. The onset of CD was significantly faster, and the symptoms were heavier in participants with a history of CD if compared to naive ones, who, however, also developed some of the symptoms. The repeatedly infected persons had elevated proportion of eosinophils 1 week post exposure (p.e.) and a stronger specific IgG but not IgM response, whereas specific IgE response was not observed. Increased serum levels of IL-4 occurred 1 and 3 week(s) p.e. in all participants. There was high variability in individual immunoblot patterns of IgG response, and no antigen with a universal diagnostic potential was confirmed. The presented analyses suggested that a complex approach can improve the accuracy of the diagnosis of CD, but component data should be interpreted carefully.

• Klíčová slova
• Allergy, Diagnosis, Immunity, Schistosome, Skin, Trichobilharzia,
• MeSH
• dermatitida imunologie   parazitologie   MeSH
• dospělí MeSH
• epidemický výskyt choroby MeSH
• imunoglobulin E krev   MeSH
• imunoglobulin G krev   MeSH
• imunoglobulin M krev   MeSH
• infekce červy třídy Trematoda diagnóza   imunologie   parazitologie   MeSH
• interleukin-4 krev   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• následné studie MeSH
• protilátky protozoální krev   MeSH
• průzkumy a dotazníky MeSH
• rybníky parazitologie   MeSH
• Schistosomatidae imunologie   MeSH
• zvířata MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• IL4 protein, human MeSH Prohlížeč
• imunoglobulin E MeSH
• imunoglobulin G MeSH
• imunoglobulin M MeSH
• interleukin-4 MeSH
• protilátky protozoální MeSH

Swimmer's itch is a re-emerging human disease caused by bird schistosome cercariae, which can infect bathing or working people in water bodies. Even if cercariae fail after penetrating the human skin, they can cause dangerous symptoms in atypical mammal hosts. One of the natural methods to reduce the presence of cercariae in the environment could lie in the introduction of non-host snail species to the ecosystem, which is known as the "dilution" or "decoy" effect. The caenogastropod Potamopyrgus antipodarum-an alien in Europe-could be a good candidate against swimmer's itch because of its apparent resistance to invasion by European bird schistosome species and its high population density. As a pilot study on this topic, we have carried out a laboratory experiment on how P. antipodarum influences the infestation of the intermediate host Radix balthica (a native lymnaeid) by the bird schistosome Trichobilharzia regenti. We found that the co-exposure of 200 P. antipodarum individuals per one R. balthica to the T. regenti miracidia under experimental conditions makes the infestation ineffective. Our results show that a non-host snail population has the potential to interfere with the transmission of a trematode via suitable snail hosts.

• Klíčová slova
• Miracidia, Potamopyrgus antipodarum, Radix balthica, Trichobilharzia regenti, “Decoy effect”,
• Publikační typ
• časopisecké články MeSH

The invasive larvae (cercariae) of schistosomes penetrate the skin of their definitive hosts. During the invasion, they undergo dramatic ultrastructural and physiological transitions. These changes result in the development of the subsequent stage, schistosomulum, which migrates through host tissues in close contact with host's immune system. One of the striking changes in the transforming cercariae is the shedding of their thick tegumental glycocalyx, which represents an immunoattractive structure; therefore its removal helps cercariae to avoid immune attack. A set of commercial fluorescently labeled lectin probes, their saccharide inhibitors and monoclonal antibodies against the trisaccharide Lewis-X antigen (LeX, CD15) were used to characterize changes in the surface saccharide composition of the neuropathogenic avian schistosome Trichobilharzia regenti during the transformation of cercariae to schistosomula, both in vitro and in vivo. The effect of various lectins on glycocalyx shedding was evaluated microscopically. The involvement of peptidases and their inhibitors on the shedding of glycocalyx was investigated using T. regenti recombinant cathepsin B2 and a set of peptidase inhibitors. The surface glycocalyx of T. regenti cercariae was rich in fucose and mannose/glucose residues. After the transformation of cercariae in vitro or in vivo within their specific duck host, reduction and vanishing of these epitopes was observed, and galactose/N-acetylgalactosamine emerged. The presence of LeX was not observed on the cercariae, but the antigen was gradually expressed from the anterior part of the body in the developing schistosomula. Some lectins which bind to the cercarial surface also induced secretion from the acetabular penetration glands. Seven lectins induced the shedding of glycocalyx by cercariae, among which five bound strongly to cercarial surface; the effect could be blocked by saccharide inhibitors. Mannose-binding protein, part of the lectin pathway of the complement system, also bound to cercariae and schistosomula, but had little effect on glycocalyx shedding. Our study did not confirm the involvement of proteolysis in glycocalyx shedding.

• MeSH
• glykokalyx metabolismus   MeSH
• glykosylace MeSH
• Schistosomatidae metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

BACKGROUND: The nasal avian schistosome Trichobilharzia regenti spends part of its intravertebrate period of life within the central nervous system. Migration of the parasites can be accompanied by neuromotor disorders or paralysis in natural definitive hosts (ducks) and even in laboratory mammals. Cercariae are also able to penetrate human skin and induce cercarial dermatitis. While the cellular and antibody responses against cercariae and migrating schistosomula have been investigated in mice, little is known about immune reactions in birds. This study first describes the dynamics of antibody response in infected ducks and identifies frequently recognized antigens that may serve as diagnostic markers of infection by T. regenti. METHODS: Groups of 35 domestic ducks and 10 mallards were exposed to different doses of T. regenti cercariae. Sera were collected at predefined time intervals and tested by ELISA for the presence of specific anti-cercarial IgY and IgM. Antigens recognized by the antibodies were identified on Western blots of cercariae and schistosomula. The applicability in immunodiagnostics was statistically evaluated by expression of specificity and sensitivity values for individual antigens. RESULTS: In ELISA, the levels of anti-cercarial IgM peaked on day 15 pi. Increased production of IgY associated with the later phases of infection was observed in most individuals around 20 dpi and culminated 30 dpi. The time course of antibody response did not differ among experimental groups, variations were only observed in the levels of specific IgY which depended rather on the age of ducks at the time of infection than on the infectious dose. On Western blots, 40 cercarial and 7 schistosomular antigens were recognized by IgY from infected ducks. Among them, 4 cercarial antigens of 50, 47, 32 and 19 kDa provided the most sensitive and specific reactions. CONCLUSIONS: Antigens of cercariae and schistosomula elicited distinct antibody response in ducks, which correlated positively with the age of animals at the time of infection. Several antigens originating in cercariae and fewer in schistosomula were recognized by IgY with diverse sensitivity and specificity; only a few seemed to be common to both stages. Four of them were considered as the most promising candidates for immunodiagnostics.

• MeSH
• antigeny helmintové imunologie   MeSH
• imunoglobulin M krev   MeSH
• imunoglobuliny krev   MeSH
• infekce červy třídy Trematoda krev   imunologie   parazitologie   veterinární   MeSH
• kachny * MeSH
• nemoci ptáků krev   imunologie   parazitologie   MeSH
• protilátky helmintové krev   MeSH
• Schistosomatidae * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antigeny helmintové MeSH
• IgY MeSH Prohlížeč
• imunoglobulin M MeSH
• imunoglobuliny MeSH
• protilátky helmintové MeSH

The neurotropic bird schistosome Trichobilharzia regenti possesses papain-like cysteine peptidases which have also been shown to be crucial enzymes in various developmental stages of the related human parasites Schistosoma spp. In this paper, we present data obtained by real-time polymerase chain reaction on the temporal distribution of transcripts of two cathepsins in different developmental stages of T. regenti: cathepsin B1 originally described from the gut lumen of schistosomula with presumptive role in nutrient digestion and cathepsin B2 originally found in penetration glands of cercariae with probable involvement in invasion of the final host. In spite of their mutual resemblance at the sequence level, the mRNA expression profiles clearly show distinct expression of cathepsins B1 and B2 during the development from eggs to cercariae. In the case of both cathepsins, the highest level of transcription was detected in intravertebrate stages. Putative functions of cathepsins B1 and B2 in schistosome developmental stages are discussed.

• MeSH
• hlemýždi MeSH
• izoenzymy genetika   metabolismus   MeSH
• kachny MeSH
• kathepsin B genetika   metabolismus   MeSH
• proteiny červů genetika   metabolismus   MeSH
• Schistosomatidae enzymologie   genetika   růst a vývoj   MeSH
• stadia vývoje MeSH
• stanovení celkové genové exprese * MeSH
• vývojová regulace genové exprese * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• izoenzymy MeSH
• kathepsin B MeSH
• proteiny červů MeSH