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Anais Da Academia Brasileira de Ciencias Jun 2011
Topics: Animals; Congresses as Topic; Schistosoma mansoni
PubMed: 21670866
DOI: 10.1590/s0001-37652011000200001 -
Current Protocols in Immunology May 2001The trematode parasites in the family Schistosomatidae (phylum Platyhelminthes) infect a wide range of vertebrates. Three species of the genus Schistosoma are of major...
The trematode parasites in the family Schistosomatidae (phylum Platyhelminthes) infect a wide range of vertebrates. Three species of the genus Schistosoma are of major medical importance. This unit deals exclusively with the parasite Schistosoma mansoni, which is the species most frequently maintained in the laboratory. Among the far-ranging investigations in the immunology of schistosomiasis are studies in vaccine development, immunopathology of granulomatous inflammation and fibrosis, eosinophil function, and in vivo regulation of T(H)1 and T(H)2 responses. This unit describes maintenance and collection procedures for various stages of the schistosome that have immunologic interest, including infection of mice with cercariae, collection of cercariae, preparation of in vitro-derived schistosomules and in vivo-derived schistosomules, and collection of adult worms and eggs. Included also are techniques for preparing soluble egg antigen (SEA), one of the more commonly used schistosome antigenic preparations. A discussion is given of the basic steps that are important in maintaining the snail intermediate host, and infecting the snails with schistosome miracidia. The unit deals exclusively with the parasite Schistosoma mansoni, which is the species most frequently maintained in the laboratory. Since part of the life cycle of all schistosomes involves a snail host, a description of proper maintenance for the snails is provided. Often, problems in experiments can be traced back to improper snail and parasite maintenance, or lack of attention to detail during mammalian exposure to the infective stage (cercaria) of the parasite.
Topics: Animals; Antigens, Helminth; Humans; Life Cycle Stages; Mice; Schistosoma mansoni; Schistosomiasis; Snails; Solubility
PubMed: 18432750
DOI: 10.1002/0471142735.im1901s28 -
PLoS Neglected Tropical Diseases Aug 2020Schistosomiasis is a water-based disease acquired through contact with cercaria-infested water. Communities living in endemic regions often rely on parasite-contaminated...
BACKGROUND
Schistosomiasis is a water-based disease acquired through contact with cercaria-infested water. Communities living in endemic regions often rely on parasite-contaminated freshwater bodies for their daily water contact activities, resulting in recurring schistosomiasis infection. In such instances, water treatment can provide safe water on a household or community scale. However, to-date there are no water treatment guidelines that provide information on how to treat water containing schistosome cercariae. Here, we rigorously test the effectiveness of chlorine against Schistosoma mansoni cercariae.
METHOD
S. mansoni cercariae were chlorinated using sodium hypochlorite under lab and field condition. The water pH was controlled at 6.5, 7.0 or 7.5, the water temperature at 20°C or 27°C, and the chlorine dose at 1, 2 or 3 mg/l. Experiments were conducted up to contact times of 45 minutes. 100 cercariae were used per experiment, thereby achieving up to 2-log10 inactivations of cercariae. Experiments were replicated under field conditions at Lake Victoria, Tanzania.
CONCLUSION
A CT (residual chlorine concentration x chlorine contact time) value of 26±4 mg·min/l is required to achieve a 2-log10 inactivation of S. mansoni cercariae under the most conservative condition tested (pH 7.5, 20°C). Field and lab-cultivated cercariae show similar chlorine sensitivities. A CT value of 30 mg·min/l is therefore recommended to disinfect cercaria-infested water, though safety factors may be required, depending on water quality and operating conditions. This CT value can be achieved with a chlorine residual of 1 mg/l after a contact time of 30 minutes, for example. This recommendation can be used to provide safe water for household and recreational water activities in communities that lack safe alternative water sources.
Topics: Animals; Cercaria; Chlorine; Halogenation; Hydrogen-Ion Concentration; Schistosoma mansoni; Schistosomiasis; Snails; Tanzania; Temperature; Water; Water Purification
PubMed: 32822356
DOI: 10.1371/journal.pntd.0008665 -
Frontiers in Immunology 2022Schistosomiasis is a disease caused by trematode parasites of the genus that affects approximately 200 million people worldwide. Schistosomiasis has been a persistent...
Schistosomiasis is a disease caused by trematode parasites of the genus that affects approximately 200 million people worldwide. Schistosomiasis has been a persistent problem in endemic areas as there is no vaccine available, currently used anti-helmintic medications do not prevent reinfection, and most concerning, drug resistance has been documented in laboratory and field isolates. Thus, alternative approaches to curtail this human disease are warranted. Understanding the immunobiology of the obligate intermediate host of these parasites, which include the freshwater snail , may facilitate the development of novel methods to stop or reduce transmission to humans. Molecules from the thioester-containing protein (TEP) superfamily have been shown to be involved in immunological functions in many animals including corals and humans. In this study we identified, characterized, and compared TEP transcripts and their expression upon exposure in resistant and susceptible strains of snails. Results showed the expression of 11 unique TEPs in snails. These transcripts present high sequence identity at the nucleotide and putative amino acid levels between susceptible and resistant strains. Further analysis revealed differences in several TEPs' constitutive expression levels between resistant and susceptible snail strains, with C3-1, C3-3, and CD109 having higher constitutive expression levels in the resistant (BS90) strain, whereas C3-2 and TEP-1 showed higher constitutive expression levels in the susceptible (NMRI) strain. Furthermore, TEP-specific response to miracidia exposure reiterated their differential expression, with resistant snails upregulating the expression of both TEP-4 and TEP-3 at 2 h and 48 h post-exposure, respectively. Further understanding the diverse TEP genes and their functions in invertebrate animal vectors will not only expand our knowledge in regard to this ancient family of immune proteins, but also offer the opportunity to identify novel molecular targets that could aid in the efforts to develop control methods to reduce schistosomiasis transmission.
Topics: Animals; Biomphalaria; Disease Susceptibility; Gene Expression; Proteins; Schistosoma mansoni; Transcription Factors
PubMed: 35967434
DOI: 10.3389/fimmu.2022.903158 -
Trends in Parasitology Nov 2018Linkage mapping - utilizing experimental genetic crosses to examine cosegregation of phenotypic traits with genetic markers - is now 100 years old. Schistosome parasites... (Review)
Review
Linkage mapping - utilizing experimental genetic crosses to examine cosegregation of phenotypic traits with genetic markers - is now 100 years old. Schistosome parasites are exquisitely well suited to linkage mapping approaches because genetic crosses can be conducted in the laboratory, thousands of progeny are produced, and elegant experimental work over the last 75 years has revealed heritable genetic variation in multiple biomedically important traits such as drug resistance, host specificity, and virulence. Application of this approach is timely because the improved genome assembly for Schistosoma mansoni and developing molecular toolkit for schistosomes increase our ability to link phenotype with genotype. We describe current progress and potential future directions of linkage mapping in schistosomes.
Topics: Animals; Chromosome Mapping; Crosses, Genetic; Genetic Markers; Genetic Variation; Genotype; Host Specificity; Phenotype; Schistosoma; Schistosoma mansoni; Schistosomiasis; Virulence
PubMed: 30150002
DOI: 10.1016/j.pt.2018.08.001 -
PLoS Neglected Tropical Diseases Oct 2021Schistosomiasis is one of the widely distributed neglected tropical diseases. It is a serious public health problem in sub-Saharan Africa. The disease is highly...
BACKGROUND
Schistosomiasis is one of the widely distributed neglected tropical diseases. It is a serious public health problem in sub-Saharan Africa. The disease is highly prevalent and widely distributed in Ethiopia due to suitable environmental factors and human activities. The prevalence and infection intensity varied from locality to locality in the country. This study aimed to assess the prevalence and intensity of S. mansoni infection and associated risk factors among schoolchildren around Lake Tana.
METHODS
A school-based cross-sectional study was conducted among 710 schoolchildren from February to April 2021 in eight selected primary schools around Lake Tana. A questionnaire was used to collect data on socio-demographic information and potential risk factors of S. mansoni infection. After collecting socio-demographic information, students were requested to bring about 2grams of stool specimens for parasitological examination. The collected stool samples were processed using a single Kato-Katz and Ritchie's concentration techniques. The data were analyzed using SPSS software version 23 and factors with a p-value < 0.05 were considered as statistically significant.
RESULTS
The overall prevalence of S. mansoni was 34.9% (95% CI: 31.4-38.7) among schoolchildren in the study area. The eggs per gram (EPG) of stool ranged from 24 to 1659 with arithmetic and geometric mean values of 138.1 EPG and 85.1 EPG, respectively. The majority of S. mansoni infections (61.4%) were classified as low infection intensity. Among the different determinant factors being male (AOR = 1.74; 95%CI = 1.233-2.457; P-value = 0.002), bathing habits (AOR = 1.494; 95%CI = 1.013-2.199; P-value = 0.043) and students attending at Qunzela primary school (AOR = 10.545; 95%CI = 3.264-34.067; P-value = 0.001), Alabo primary school (AOR = 3.386; 95%CI = 1.084-10.572; P-value = 0.036) were significantly associated with S. mansoni infection.
CONCLUSION
This study revealed that more than one-third of schoolchildren were infected by S. mansoni in the study area. The majority of the infections were classified as low infection intensity. Being male, bathing habits and schools in which students attended were independent explanatory factors for S. mansoni infection. Therefore, integrated control strategies are needed to improve the health conditions of schoolchildren in the study area.
Topics: Adolescent; Animals; Child; Child, Preschool; Cross-Sectional Studies; Ethiopia; Feces; Female; Humans; Lakes; Male; Risk Factors; Schistosoma mansoni; Schistosomiasis mansoni; Schools; Students; Young Adult
PubMed: 34705817
DOI: 10.1371/journal.pntd.0009861 -
Molecular Biotechnology Nov 2021Schistosomiasis causes significant morbidity and mortality. Vaccine efforts to date indicate the need to increase the immunogenicity of Schistosoma antigens. The...
Schistosomiasis causes significant morbidity and mortality. Vaccine efforts to date indicate the need to increase the immunogenicity of Schistosoma antigens. The multiple antigen-presenting system, whereby proteins are genetically fused to rhizavidin and affinity linked to biotinylated templates, enables the generation of robust immune responses. The objective of this work was to express and purify the S. mansoni antigens, SmTSP-2 and SmCD59.2, in fusion with rhizavidin. The fusion with rhizavidin greatly decreased the expression level of rSmTSP-2, but not rSmCD59.2, and both were expressed in the insoluble fraction, requiring optimization of culture conditions. Evaluation of different E. coli strains and media showed that BL21-DE3 cultured in Terrific Broth provided the highest expression levels of both proteins. Investigation of a range of time and temperature of induction showed that E. coli strains expressing rRzv:SmTSP-2 and rRzv:SmCD59.2 showed the highest protein production at 23 °C for 15 h. Recombinant proteins were purified by a single step of affinity chromatography allowing isolation of these proteins in high concentration and purity. The optimization process increased final soluble protein yield of rRzv:SmTSP-2 by fourfold and rRzv:SmCD59.2 by tenfold, providing ~ 20 mg/L of each protein. Optimized fusion protein production will allow antigen use in biotin-rhizavidin affinity platforms.
Topics: Animals; Antigens, Helminth; Bacterial Proteins; Chromatography, Affinity; Recombinant Fusion Proteins; Schistosoma mansoni; Schistosomiasis mansoni
PubMed: 34165770
DOI: 10.1007/s12033-021-00355-2 -
Parasitology May 2020Schistosoma mansoni is the most common species causing schistosomiasis. It has a complex life cycle involving a vertebrate definitive host and a snail intermediate host... (Review)
Review
Schistosoma mansoni is the most common species causing schistosomiasis. It has a complex life cycle involving a vertebrate definitive host and a snail intermediate host of the genus Biomphalaria. Each stage encounters a plethora of environmental stresses specially heat stress. Another sort of stress arises from repeated exposure of the parasite to praziquantel (PZQ), the only drug used for treatment, which leads to the development of resistance in the fields and the labs. Heat shock protein 70 (Hsp70) is found in different developmental stages of S. mansoni. It is immunogenic and regulate cercarial invasion besides its chaperone function. In the Biomphalaria/S. mansoni interaction, epigenetic modulations of the Hsp70 gene underscore the susceptibility phenotype of the snail. Hsp70 is up-regulated in adult S. mansoni with decreased sensitivity to PZQ. This could be due to the induction of oxidative and endoplasmic reticulum stress, induction of apoptosis, exposure to the stressful drug pressure and increase influx of calcium ions. Up-regulation of Hsp70 might help the worm to survive the schistosomicidal effect of the drug mainly by dealing with misfolded proteins, inhibition of apoptosis, induction of autophagy, up-regulation of the P-glycoprotein transporter and attenuation of the signalling from G protein coupled receptors.
Topics: Animals; Anthelmintics; Drug Resistance; HSP70 Heat-Shock Proteins; Helminth Proteins; Praziquantel; Schistosoma mansoni
PubMed: 32127065
DOI: 10.1017/S0031182020000347 -
Scientific Reports Jan 2022Patterns of diversity in pathogen genomes provide a window into the spatiotemporal spread of disease. In this study, we tested the hypothesis that Schistosoma mansoni...
Patterns of diversity in pathogen genomes provide a window into the spatiotemporal spread of disease. In this study, we tested the hypothesis that Schistosoma mansoni parasites form genetic clusters that coincide with the communities of their human hosts. We also looked for genetic clustering of parasites at the sub-community level. Our data consists of 14 microsatellite DNA markers, typed from pooled DNA samples from [Formula: see text] infected individuals living in three Brazilian communities. We found a one-to-one correspondence between genetic clusters found by K-means cluster analysis and communities when [Formula: see text]. These clusters are also easily identified in a neighbor-joining tree and principal coordinates plots. K-means analysis with [Formula: see text] also reveals genetic clusters of parasites at the sub-community level. These sub-clusters also appear on the neighbor-joining tree and principal coordinates plots. A surprising finding is a genetic relationship between subgroups in widely separated human communities. This connection suggests the existence of common transmission sites that have wide influence. In summary, the genetic structure of S. mansoni in Brazil juxtaposes local isolation that is occasionally broken by long-range migration. Permanent eradication of schistosomes will require both local efforts and the identification of regional infection reservoirs.
Topics: Animals; Brazil; Cluster Analysis; Genetics, Population; Host-Parasite Interactions; Humans; Microsatellite Repeats; Schistosoma mansoni; Schistosomiasis mansoni
PubMed: 35058485
DOI: 10.1038/s41598-022-04776-0 -
International Journal of Molecular... Jul 2015The present study describes a real-time PCR approach with high resolution melting-curve (HRM) assay developed for the detection and differentiation of Schistosoma...
The present study describes a real-time PCR approach with high resolution melting-curve (HRM) assay developed for the detection and differentiation of Schistosoma mansoni and S. haematobium in fecal and urine samples collected from rural Yemen. The samples were screened by microscopy and PCR for the Schistosoma species infection. A pair of degenerate primers were designed targeting partial regions in the cytochrome oxidase subunit I (cox1) gene of S. mansoni and S. haematobium using real-time PCR-HRM assay. The overall prevalence of schistosomiasis was 31.8%; 23.8% of the participants were infected with S. haematobium and 9.3% were infected with S. mansoni. With regards to the intensity of infections, 22.1% and 77.9% of S. haematobium infections were of heavy and light intensities, respectively. Likewise, 8.1%, 40.5% and 51.4% of S. mansoni infections were of heavy, moderate and light intensities, respectively. The melting points were distinctive for S. mansoni and S. haematobium, categorized by peaks of 76.49 ± 0.25 °C and 75.43 ± 0.26 °C, respectively. HRM analysis showed high detection capability through the amplification of Schistosoma DNA with as low as 0.0001 ng/µL. Significant negative correlations were reported between the real-time PCR-HRM cycle threshold (Ct) values and microscopic egg counts for both S. mansoni in stool and S. haematobium in urine (p < 0.01). In conclusion, this closed-tube HRM protocol provides a potentially powerful screening molecular tool for the detection of S. mansoni and S. haematobium. It is a simple, rapid, accurate, and cost-effective method. Hence, this method is a good alternative approach to probe-based PCR assays.
Topics: Animals; DNA Primers; Nucleic Acid Denaturation; Real-Time Polymerase Chain Reaction; Schistosoma haematobium; Schistosoma mansoni; Schistosomiasis; Sensitivity and Specificity; Temperature
PubMed: 26193254
DOI: 10.3390/ijms160716085