51
|
Zhang GJ, Qiu CP, Qiu DC, Xia MY. [Study on molecular phylogeny of Schistosoma sinensium based on mitochondrial genes]. Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi 2010; 20:10-3. [PMID: 12567532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Abstract
OBJECTIVE To determine the phylogenetic position of Schistosoma sinensium in the genus Schistosoma using mitochondrial cytochrome C oxidase 1 (CO1) and NADH dehydrogenase 1(ND1) as molecular markers. METHODS The genomic DNA of adult worms were extracted by the GNT-K method. The target regions were amplified by PCR using specific primers. The PCR products were purified before ligation into the plasmid Zero-Blunt. Recombinant plasmids were amplified in E. coli, extracted and purified using routine methods and then sequenced using M13 primers (F/R) on a Licor long-read auto-sequencer. Sequences of related schistosomes were retrieved from GenBank and aligned with our data in the sequence editor ESEE. Gene trees were constructed in PHYLIP and MEGA using both maximum parsimony and neighbor-joining methods. For parsimony analysis, all characters were treated as unordered and with equal weights. At least 3,000 cycles of bootstrapping were carried out. For analysis in MEGA, all gap columns were deleted. The third position of codon was included. RESULTS The nucleotide and amino acid sequences of CO1 and ND1 of S. sinensium were obtained. CONCLUSION The phylogenetic trees from these molecular data suggested that S. sinensium belongs to the Asian schistosome group, and the results coincided with the previous rDNA (ITS2 & LSU) analysis results.
Collapse
Affiliation(s)
- Guang-jun Zhang
- Institute for Parasitic Disease Control and Prevention, Chinese Center for Disease Control and Prenention, Shanghai 200025
| | | | | | | |
Collapse
|
52
|
Steinauer ML, Blouin MS, Criscione CD. Applying evolutionary genetics to schistosome epidemiology. Infection, Genetics and Evolution 2010; 10:433-43. [PMID: 20176142 PMCID: PMC2861999 DOI: 10.1016/j.meegid.2010.02.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Revised: 02/09/2010] [Accepted: 02/15/2010] [Indexed: 10/19/2022]
Abstract
We review how molecular markers and evolutionary analysis have been applied to the study of schistosome parasites, important pathogens that infect over 200 million people worldwide. Topics reviewed include phylogenetics and biogeography, hybridization, infection within snails, mating systems, and genetic structure. Some interesting generalizations include that schistosome species hybridize frequently and have switched definitive hosts repeatedly in evolutionary time. We show that molecular markers can be used to infer epidemiologically relevant processes such as spatial variation in transmission, or to reveal complex patterns of mate choice. Analysis of genetic structure data shows that transmission foci can be structured by watershed boundaries, habitat types, and host species. We also discuss sampling and analytical problems that arise when using larvae to estimate genetic parameters of adult schistosome populations. Finally, we review pitfalls in methodologies such as genotyping very small individuals, statistical methods for identifying clonemates or for identifying sibling groups, and estimating allele frequencies from pooled egg samples.
Collapse
Affiliation(s)
- Michelle L Steinauer
- Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, 105 Magruder Hall, Corvallis, OR 97331, United States.
| | | | | |
Collapse
|
53
|
Gomes LI, Marques LHDS, Enk MJ, de Oliveira MC, Coelho PMZ, Rabello A. Development and evaluation of a sensitive PCR-ELISA system for detection of schistosoma infection in feces. PLoS Negl Trop Dis 2010; 4:e664. [PMID: 20421918 PMCID: PMC2857640 DOI: 10.1371/journal.pntd.0000664] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Accepted: 03/09/2010] [Indexed: 11/18/2022] Open
Abstract
Background A PCR-enzyme-linked immunosorbent assay (PCR-ELISA) was developed to overcome the need for sensitive techniques for the efficient diagnosis of Schistosoma infection in endemic settings with low parasitic burden. Methodology/Principal Findings This system amplifies a 121-base pair tandem repeat DNA sequence, immobilizes the resultant 5′ biotinylated product on streptavidin-coated strip-well microplates and uses anti-fluorescein antibodies conjugated to horseradish peroxidase to detect the hybridized fluorescein-labeled oligonucleotide probe. The detection limit of the Schistosoma PCR-ELISA system was determined to be 1.3 fg of S. mansoni genomic DNA (less than the amount found in a single cell) and estimated to be 0.15 S. mansoni eggs per gram of feces (fractions of an egg). The system showed good precision and genus specificity since the DNA target was found in seven Schistosoma DNA samples: S. mansoni, S. haematobium, S. bovis, S. intercalatum, S. japonicum, S. magrebowiei and S. rhodaini. By evaluating 206 patients living in an endemic area in Brazil, the prevalence of S. mansoni infection was determined to be 18% by examining 12 Kato-Katz slides (41.7 mg/smear, 500 mg total) of a single fecal sample from each person, while the Schistosoma PCR-ELISA identified a 30% rate of infection using 500-mg of the same fecal sample. When considering the Kato-Katz method as the reference test, artificial sensitivity and specificity rates of the PCR-ELISA system were 97.4% and 85.1%, respectively. The potential for estimating parasitic load by DNA detection in feces was assessed by comparing absorbance values and eggs per gram of feces, with a Spearman correlation coefficient of 0.700 (P<0.0001). Conclusions/Significance This study reports the development and field evaluation of a sensitive Schistosoma PCR-ELISA, a system that may serve as an alternative for diagnosing Schistosoma infection. Schistosomiasis is a neglected disease caused by worms of the genus Schistosoma. The transmission cycle requires contamination of bodies of water by parasite eggs present in excreta, specific snails as intermediate hosts and human contact with water. Fortunately, relatively safe and easily administrable drugs are available and, as the outcome of repeated treatment, a reduction of severe clinical forms and a decrease in the number of infected persons has been reported in endemic areas. The routine method for diagnosis is the microscopic examination but it fails when there are few eggs in the feces, as usually occurs in treated but noncured persons or in areas with low levels of transmission. This study reports the development of the PCR-ELISA system for the detection of Schistosoma DNA in human feces as an alternative approach to diagnose light infections. The system permits the enzymatic amplification of a specific region of the DNA from minute amounts of parasite material. Using the proposed PCR-ELISA approach for the diagnosis of a population in an endemic area in Brazil, 30% were found to be infected, as compared with the 18% found by microscopic fecal examination. Although the technique requires a complex laboratory infrastructure and specific funding it may be used by control programs targeting the elimination of schistosomiasis.
Collapse
Affiliation(s)
- Luciana Inácia Gomes
- Laboratório de Pesquisas Clínicas, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (Fiocruz), Belo Horizonte, Minas Gerais, Brazil
| | - Letícia Helena dos Santos Marques
- Laboratório de Pesquisas Clínicas, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (Fiocruz), Belo Horizonte, Minas Gerais, Brazil
| | - Martin Johannes Enk
- Laboratório de Esquistossomose, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (Fiocruz), Belo Horizonte, Minas Gerais, Brazil
| | - Maria Cláudia de Oliveira
- Laboratório de Pesquisas Clínicas, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (Fiocruz), Belo Horizonte, Minas Gerais, Brazil
| | - Paulo Marcos Zech Coelho
- Laboratório de Esquistossomose, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (Fiocruz), Belo Horizonte, Minas Gerais, Brazil
| | - Ana Rabello
- Laboratório de Pesquisas Clínicas, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz (Fiocruz), Belo Horizonte, Minas Gerais, Brazil
- * E-mail:
| |
Collapse
|
54
|
Kato-Hayashi N, Kirinoki M, Iwamura Y, Kanazawa T, Kitikoon V, Matsuda H, Chigusa Y. Identification and differentiation of human schistosomes by polymerase chain reaction. Exp Parasitol 2009; 124:325-9. [PMID: 19948171 DOI: 10.1016/j.exppara.2009.11.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2009] [Revised: 11/06/2009] [Accepted: 11/16/2009] [Indexed: 11/19/2022]
Abstract
Recent increasing number of travelers, immigrants and foreign workers from schistosomiasis endemic area has thus resulted in the importation of schistosomiasis to non-endemic countries. To avoid ova-induced pathogenicity, sensitive and specific diagnostic means at an early stage of infection are therefore crucial. In this study, we developed polymerase chain reaction (PCR) primers specific for human schistosome species. The PCR products were obtained in a species-specific manner (479 bp, Schistosoma mansoni; 365 bp, S. haematobium; 614 bp, S. japonicum; 303 bp, S. mekongi) and were detectable from 0.01 pg of total worm DNA (S. haematobium, S. japonicum, S. mekongi). The primer sets were also available for multiplex use. Although some difficulties were experienced in amplifying the parasite DNA from the infected animals, schistosome DNA could be detected from one day post infection. The PCR method described herein will therefore be beneficial to detect human schistosomiasis, after some improvements in this method.
Collapse
Affiliation(s)
- Naoko Kato-Hayashi
- Laboratory of Tropical Medicine and Parasitology, Dokkyo Medical University, Tochigi, Japan.
| | | | | | | | | | | | | |
Collapse
|
55
|
Pierce RJ, Mitta G, Roger E. [Schistosome genomes: a key step in the war on the worm]. Med Sci (Paris) 2009; 25:761-2. [PMID: 19765394 DOI: 10.1051/medsci/2009258-9761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
56
|
Wichmann D, Panning M, Quack T, Kramme S, Burchard GD, Grevelding C, Drosten C. Diagnosing schistosomiasis by detection of cell-free parasite DNA in human plasma. PLoS Negl Trop Dis 2009; 3:e422. [PMID: 19381285 PMCID: PMC2667260 DOI: 10.1371/journal.pntd.0000422] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Accepted: 03/26/2009] [Indexed: 01/19/2023] Open
Abstract
Introduction Schistosomiasis (bilharzia), one of the most relevant parasitoses of humans, is confirmed by microscopic detection of eggs in stool, urine, or organ biopsies. The sensitivity of these procedures is variable due to fluctuation of egg shedding. Serological tests on the other hand do not distinguish between active and past disease. In patients with acute disease (Katayama syndrome), both serology and direct detection may produce false negative results. To overcome these obstacles, we developed a novel diagnostic strategy, following the rationale that Schistosoma DNA may be liberated as a result of parasite turnover and reach the blood. Cell-free parasite DNA (CFPD) was detected in plasma by PCR. Methodology/Principal Findings Real-time PCR with internal control was developed and optimized for detection of CFPD in human plasma. Distribution was studied in a mouse model for Schistosoma replication and elimination, as well as in human patients seen before and after treatment. CFPD was detectable in mouse plasma, and its concentration correlated with the course of anti-Schistosoma treatment. Humans with chronic disease and eggs in stool or urine (n = 14) showed a 100% rate of CFPD detection. CFPD was also detected in all (n = 8) patients with Katayama syndrome. Patients in whom no viable eggs could be detected and who had been treated for schistomiasis in the past (n = 30) showed lower detection rates (33.3%) and significantly lower CFPD concentrations. The duration from treatment to total elimination of CFPD from plasma was projected to exceed one year. Conclusions/Significance PCR for detection of CFPD in human plasma may provide a new laboratory tool for diagnosing schistosomiasis in all phases of clinical disease, including the capacity to rule out Katayama syndrome and active disease. Further studies are needed to confirm the clinical usefulness of CFPD quantification in therapy monitoring. Bilharzia (schistosomiasis) occurs in the tropics and subtropics and is one of the most important parasite diseases of humans. It is caused by flukes residing in the vessels of the gut or bladder, causing fever, pain, and bleeding. Bladder cancer or esophageal varices may follow. Diagnosis is difficult, requiring detection of parasite eggs in stool, urine, or gut/bladder biopsies. In this paper, we introduce a fundamentally new way of diagnosing bilharzia from the blood. It has been known for almost 20 years that patients with cancer have tumor-derived DNA circulating in their blood, which can be used for diagnostic purposes. During pregnancy, free DNA from the fetus can be detected in motherly blood, which can be used for diagnosing a range of fetal diseases and pregnancy-associated complications. We found that parasite DNA can be detected in the same way in the blood of patients with bilharzia. In patients with early disease, diagnosis was possible earlier than with any other test. DNA could be detected in all patients with active disease in our study. Patients after treatment had significantly lower parasite DNA concentrations and turned negative 1–2 years after treatment. Future studies should implement the method in large cohorts of patients and should define criteria for the confirmation of the success of treatment by comparing the concentration of fluke DNA before and after therapy.
Collapse
Affiliation(s)
- Dominic Wichmann
- Sektion Infektiologie und Tropenmedizin, I. Medizinische Klinik, Universitätsklinikum Eppendorf, Hamburg, Germany
| | - Marcus Panning
- Clinical Virology Group, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Thomas Quack
- Institute of Parasitology, Faculty of Veterinary Medicine, Justus Liebig University, Giessen, Germany
| | - Stefanie Kramme
- Clinical Virology Group, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Gerd-Dieter Burchard
- Sektion Infektiologie und Tropenmedizin, I. Medizinische Klinik, Universitätsklinikum Eppendorf, Hamburg, Germany
| | - Christoph Grevelding
- Institute of Parasitology, Faculty of Veterinary Medicine, Justus Liebig University, Giessen, Germany
| | - Christian Drosten
- Clinical Virology Group, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- * E-mail:
| |
Collapse
|
57
|
Qian MB, Hu W. [The structure and function of schistosome tegument and related proteomic study]. Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi 2008; 26:466-471. [PMID: 19288927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Schistosome is covered by a living syncytium, called tegument, which plays important role in nutrient uptake and immune evasion. Recently, tegumental proteomic research identified lots of proteins, of which there may be potential targets for diagnosis, drugs and vaccines.
Collapse
Affiliation(s)
- Men-bao Qian
- National Institute of Parasitic Diseases, Chinese Centre for Disease Control and Prevention, Key Laboratory of Parasite and Vector Biology, WHO Collaborating Centre for Malaria, Schistosomiasis and Filariasis, Shanghai 200025, China
| | | |
Collapse
|
58
|
Githui EK, Damian RT, Aman RA, Ali MA, Kamau JM. Schistosoma spp.: Isolation of microtubule associated proteins in the tegument and the definition of dynein light chains components. Exp Parasitol 2008; 121:96-104. [PMID: 18996374 DOI: 10.1016/j.exppara.2008.10.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Revised: 10/05/2008] [Accepted: 10/08/2008] [Indexed: 11/17/2022]
Abstract
Schistosomes are parasitic blood flukes that reside in human mesenteric veins or urinary bladder veins, depending on species of the parasite. The syncytial tegument of these parasites represents a dynamic interface that regulates nutritional and immunological interactions between the parasite and the host. It is known that the components for biogenesis and maintenance of the tegument are supplied via vesicles from the nucleated cell bodies beneath the syncytium and muscle layer. To investigate the common motor components of vesicular transport in the tegument of schistomes, we extracted Schistosoma mansoni tegumental microtubule associated proteins utilizing detergent/high-salt procedure and raised antiserum against these proteins. The antiserum was applied to screen Schistosoma haematobium lambda gt11 expression library and some of the isolated clones were sequenced. Blast search for the sequences against NCBI database identified clones that are dynein light chains and myosin genes. Further analysis of schistosome dynein genes in the databases identified three families of dynein light chains (Dlcs). The Tctex family protein sequences are significantly different from the mammalian homologs and, therefore, offer a potential vaccine/drug target against schistosomes.
Collapse
Affiliation(s)
- Elijah K Githui
- Department of Molecular Genetics, Institute of Primate Research/National Museums of Kenya, P.O. Box 40658, Nairobi, Kenya.
| | | | | | | | | |
Collapse
|
59
|
Beltran S, Cézilly F, Boissier J. Genetic dissimilarity between mates, but not male heterozygosity, influences divorce in schistosomes. PLoS One 2008; 3:e3328. [PMID: 18841198 PMCID: PMC2553268 DOI: 10.1371/journal.pone.0003328] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Accepted: 09/04/2008] [Indexed: 11/29/2022] Open
Abstract
Background Correlational studies strongly suggest that both genetic similarity and heterozygosity can influence female mate choice. However, the influence of each variable has usually been tested independently, although similarity and heterozygosity might be correlated. We experimentally determined the relative influence of genetic similarity and heterozygosity in divorce and re-mating in the monogamous endoparasite Schistosoma mansoni. Methodology/Principal Findings We performed sequential infections of vertebrate hosts with controlled larval populations of parasites, where sex and individual genetic diversity and similarity were predetermined before infection. Divorce rate increased significantly when females were given the opportunity to increase genetic dissimilarity through re-mating with a new partner, independently of the intensity of male-male competition. We found however no evidence for females attempting to maximize the level of heterozygosity of their reproductive partner through divorce. Conclusions/Significance Female preference for genetically dissimilar males should result in more heterozygous offspring. Because genetic heterozygosity might partly determine the ability of parasites to counter host resistance, adaptive divorce could be an important factor in the evolutionary arms race between schistosomes and their hosts.
Collapse
Affiliation(s)
- Sophie Beltran
- Laboratoire de Biologie et d'Ecologie Tropicale et Méditerranéenne, UMR 5244 CNRS-EPHE-UPVD, Université de Perpignan, Perpignan, France
| | - Frank Cézilly
- Equipe Ecologie Evolutive, UMR CNRS 5561 Biogéosciences, Université de Bourgogne, Dijon, France
| | - Jérôme Boissier
- Laboratoire de Biologie et d'Ecologie Tropicale et Méditerranéenne, UMR 5244 CNRS-EPHE-UPVD, Université de Perpignan, Perpignan, France
- * E-mail:
| |
Collapse
|
60
|
Abstract
Schistosomes represent a unique animal model for comparative analyses of monogamy. Indeed, schistosomes are classified at the lowest taxonomical level of monogamous species and lack complex social interactions, which could alter our understanding of their unusual mating system. Elements discussed here include the fact that monogamy in schistosomes could be an ancestral state between hermaphroditism and polygyny or polygynandry and the occurrence of mate changes. In addition, hypotheses are proposed to explain monogamy in schistosomes (e.g. female dispersion, the need for paternal care, oviposition site limitation or aggressiveness, and mate guarding). We also propose future experimental and analytical approaches to improve our understanding of the schistosomes' mating system.
Collapse
Affiliation(s)
- S Beltran
- UMR 5244 CNRS-EPHE-UPVD, Parasitologie Fonctionnelle et Evolutive, Laboratoire de Biologie et d'Ecologie Tropicale et Méditerranéenne, 52 Avenue Paul Alduy, 66 860 Perpignan, France
| | | |
Collapse
|
61
|
Dillon GP, Feltwell T, Skelton J, Coulson PS, Wilson RA, Ivens AC. Altered patterns of gene expression underlying the enhanced immunogenicity of radiation-attenuated schistosomes. PLoS Negl Trop Dis 2008; 2:e240. [PMID: 18493602 PMCID: PMC2375114 DOI: 10.1371/journal.pntd.0000240] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Accepted: 04/23/2008] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Schistosome cercariae only elicit high levels of protective immunity against a challenge infection if they are optimally attenuated by exposure to ionising radiation that truncates their migration in the lungs. However, the underlying molecular mechanisms responsible for the altered phenotype of the irradiated parasite that primes for protection have yet to be identified. METHODOLOGY/PRINCIPAL FINDINGS We have used a custom microarray comprising probes derived from lung-stage parasites to compare patterns of gene expression in schistosomula derived from normal and irradiated cercariae. These were transformed in vitro and cultured for four, seven, and ten days to correspond in development to the priming parasites, before RNA extraction. At these late times after the radiation insult, transcript suppression was the principal feature of the irradiated larvae. Individual gene analysis revealed that only seven were significantly down-regulated in the irradiated versus normal larvae at the three time-points; notably, four of the protein products are present in the tegument or associated with its membranes, perhaps indicating a perturbed function. Grouping of transcripts using Gene Ontology (GO) and subsequent Gene Set Enrichment Analysis (GSEA) proved more informative in teasing out subtle differences. Deficiencies in signalling pathways involving G-protein-coupled receptors suggest the parasite is less able to sense its environment. Reduction of cytoskeleton transcripts could indicate compromised structure which, coupled with a paucity of neuroreceptor transcripts, may mean the parasite is also unable to respond correctly to external stimuli. CONCLUSIONS/SIGNIFICANCE The transcriptional differences observed are concordant with the known extended transit of attenuated parasites through skin-draining lymph nodes and the lungs: prolonged priming of the immune system by the parasite, rather than over-expression of novel antigens, could thus explain the efficacy of the irradiated vaccine.
Collapse
Affiliation(s)
- Gary P Dillon
- Department of Biology, University of York, York, United Kingdom.
| | | | | | | | | | | |
Collapse
|
62
|
Steinauer ML, Mwangi IN, Maina GM, Kinuthia JM, Mutuku MW, Agola EL, Mungai B, Mkoji GM, Loker ES. Interactions between natural populations of human and rodent schistosomes in the Lake Victoria region of Kenya: a molecular epidemiological approach. PLoS Negl Trop Dis 2008; 2:e222. [PMID: 18414646 PMCID: PMC2291567 DOI: 10.1371/journal.pntd.0000222] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2007] [Accepted: 03/10/2008] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Schistosoma mansoni exists in a complex environmental milieu that may select for significant evolutionary changes in this species. In Kenya, the sympatric distribution of S. mansoni with S. rodhaini potentially influences the epidemiology, ecology, and evolutionary biology of both species, because they infect the same species of snail and mammalian hosts and are capable of hybridization. METHODOLOGY/PRINCIPAL FINDINGS Over a 2-year period, using a molecular epidemiological approach, we examined spatial and temporal distributions, and the overlap of these schistosomes within snails, in natural settings in Kenya. Both species had spatially and temporally patchy distributions, although S. mansoni was eight times more common than S. rodhaini. Both species were overdispersed within snails, and most snails (85.2% for S. mansoni and 91.7% for S. rodhaini) only harbored one schistosome genotype. Over time, half of snails infected with multiple genotypes showed a replacement pattern in which an initially dominant genotype was less represented in later replicates. The other half showed a consistent pattern over time; however, the ratio of each genotype was skewed. Profiles of circadian emergence of cercariae revealed that S. rodhaini emerges throughout the 24-hour cycle, with peak emergence before sunrise and sometimes immediately after sunset, which differs from previous reports of a single nocturnal peak immediately after sunset. Peak emergence for S. mansoni cercariae occurred as light became most intense and overlapped temporally with S. rodhaini. Comparison of schistosome communities within snails against a null model indicated that the community was structured and that coinfections were more common than expected by chance. In mixed infections, cercarial emergence over 24 hours remained similar to single species infections, again with S. rodhaini and S. mansoni cercarial emergence profiles overlapping substantially. CONCLUSIONS/SIGNIFICANCE The data from this study indicate a lack of obvious spatial or temporal isolating mechanisms to prevent hybridization, raising the intriguing question of how the two species retain their separate identities.
Collapse
|
63
|
Attwood SW, Fatih FA, Upatham ES. DNA-sequence variation among Schistosoma mekongi populations and related taxa; phylogeography and the current distribution of Asian schistosomiasis. PLoS Negl Trop Dis 2008; 2:e200. [PMID: 18350111 PMCID: PMC2265426 DOI: 10.1371/journal.pntd.0000200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Accepted: 01/23/2008] [Indexed: 02/05/2023] Open
Abstract
Background Schistosomiasis in humans along the lower Mekong River has proven a persistent public health problem in the region. The causative agent is the parasite Schistosoma mekongi (Trematoda: Digenea). A new transmission focus is reported, as well as the first study of genetic variation among S. mekongi populations. The aim is to confirm the identity of the species involved at each known focus of Mekong schistosomiasis transmission, to examine historical relationships among the populations and related taxa, and to provide data for use (a priori) in further studies of the origins, radiation, and future dispersal capabilities of S. mekongi. Methodology/Principal Findings DNA sequence data are presented for four populations of S. mekongi from Cambodia and southern Laos, three of which were distinguishable at the COI (cox1) and 12S (rrnS) mitochondrial loci sampled. A phylogeny was estimated for these populations and the other members of the Schistosoma sinensium group. The study provides new DNA sequence data for three new populations and one new locus/population combination. A Bayesian approach is used to estimate divergence dates for events within the S. sinensium group and among the S. mekongi populations. Conclusions/Significance The date estimates are consistent with phylogeographical hypotheses describing a Pliocene radiation of the S. sinensium group and a mid-Pleistocene invasion of Southeast Asia by S. mekongi. The date estimates also provide Bayesian priors for future work on the evolution of S. mekongi. The public health implications of S. mekongi transmission outside the lower Mekong River are also discussed. Schistosomiasis is a disease caused by parasitic worms of the genus Schistosoma. In the lower Mekong river, schistosomiasis in humans is called Mekong schistosomiasis and is caused by Schistosoma mekongi. In the past, Mekong schistosomiasis was known only from the lower Mekong river. Here DNA-sequence variation is used to study the relationships and history of populations of S. mekongi. Populations from other rivers are compared and shown to be S. mekongi, thus confirming that this species is not restricted to only a small section of one river. The dates of divergence among populations are also estimated. Prior to this study it was assumed that S. mekongi originated in Yunnan, China, migrated southwards across Laos and into Cambodia, later becoming extinct in Laos (due to conditions unsuitable for transmission). In contrast, the dates estimated here indicate that S. mekongi entered Cambodia from Vietnam, 2.5–1 Ma. The pattern of genetic variation fits better with a more recent, and ongoing, northwards migration from Cambodia into Laos. The implications are that Mekong schistosomiasis is more widespread than once thought and that the human population at risk is up to 10 times greater than originally estimated. There is also an increased possibility of the spread of Mekong schistosomiasis across Laos.
Collapse
Affiliation(s)
- Stephen W Attwood
- State Key Laboratory of Biotherapy, West China Hospital, West China Medical School, Sichuan University, Chengdu, People's Republic of China.
| | | | | |
Collapse
|
64
|
Abstract
An effective schistosome vaccine is a desirable control tool but progress towards that goal has been slow. Protective immunity has been difficult to demonstrate in humans, particularly children, so no routes to a vaccine have emerged from that source. The concept of concomitant immunity appeared to offer a paradigm for a vaccine operating against incoming larvae in the skin but did not yield the expected dividends. The mining of crude parasite extracts, the use of monoclonal antibodies and protein selection based on immunogenicity produced a panel of vaccine candidates, mostly of cytoplasmic origin. However, none of these performed well in independent rodent trials, but glutathione-S-transferase from Schistosoma haematobium is currently undergoing clinical trials as an anti-fecundity vaccine. The sequencing of the S. mansoni transcriptome and genome and the development of proteomic and microarray technologies has dramatically improved the possibilities for identifying novel vaccine candidates, particularly proteins secreted from or exposed at the surface of schistosomula and adult worms. These discoveries are leading to a new round of protein expression and protection experiments that will enable us to evaluate systematically all the major targets available for immune intervention. Only then will we know if schistosomes have an Achilles' heel.
Collapse
Affiliation(s)
- R Alan Wilson
- Department of Biology, University of York, York, UK.
| | | |
Collapse
|
65
|
Acosta D, Cancela M, Piacenza L, Roche L, Carmona C, Tort JF. Fasciola hepatica leucine aminopeptidase, a promising candidate for vaccination against ruminant fasciolosis. Mol Biochem Parasitol 2007; 158:52-64. [PMID: 18178266 DOI: 10.1016/j.molbiopara.2007.11.011] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Revised: 11/08/2007] [Accepted: 11/14/2007] [Indexed: 11/17/2022]
Abstract
Leucyl aminopeptidases (LAP) from different parasitic organisms are attracting attention as relevant players in parasite biology, and consequently being considered as candidates for drug and vaccine design. In fact, the highest protection level achieved in ruminant immunization by a native antigen was previously reported by us, using a purified LAP as immunogen in a sheep trial against fasciolosis. Here, we report the cloning of a full-length cDNA from adult F. hepatica encoding a member of the M17 family of LAP (FhLAP) and functional expression and characterization of the corresponding enzyme. FhLAP was closely related to Schistosoma LAPs, but interestingly distant from their mammalian host's homologues, and was expressed in all stages of the parasite life cycle. The recombinant enzyme, functionally expressed in Escherichia coli, showed a marked amidolytic preference against the synthetic aminopeptidase substrate l-leucine-7-amino-4-methylcoumarin (Leu-AMC) and was also active against Cys-AMC and Met-AMC. Both native and recombinant enzyme were stimulated by the addition of divalent cations predominantly Mn(2+), and strongly inhibited by bestatin and cysteine. Physico-chemical properties, localization by immunoelectron microscopy, MALDI-TOF analysis, and cross-reactivity of anti-rFhLAP immune serum demonstrated that the recombinant enzyme was identical to the previously purified gut-associated LAP from adult F. hepatica. Vaccination trials using rFhLAP for rabbit immunization showed a strong IgG response and a highly significant level of protection after experimental infection with F. hepatica metacercariae, confirming that FhLAP is a relevant candidate for vaccine development.
Collapse
Affiliation(s)
- Daniel Acosta
- Unidad de Biología Parasitaria, Instituto de Higiene, Facultad de Ciencias, Uruguay
| | | | | | | | | | | |
Collapse
|
66
|
Attwood SW, Fatih FA, Mondal MMH, Alim MA, Fadjar S, Rajapakse RPVJ, Rollinson D. A DNA sequence-based study of theSchistosoma indicum(Trematoda: Digenea) group: population phylogeny, taxonomy and historical biogeography. Parasitology 2007; 134:2009-20. [PMID: 17822572 DOI: 10.1017/s0031182007003411] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
SUMMARYPartial (DNA) sequences were collected for 2 mitochondrial loci (SrrnaandLrrna, therrnS andrrnL rRNA genes respectively) forSchistosoma indicumgroup species from 4 Southeast Asian countries. The samples included 7 populations, 4 of which were previously unstudied. In 11 cases the combination of locus and population was new. The aim of the study was to provide a phylogeny based on new independent data and multiple populations (earlier studies had mostly used a common set of field samples or laboratory lines) and to examine interrelationships and phylogeography within this species group. Paraphyly of theS. indicumgroup was confirmed, as was the basal position ofSchistosoma incognitumin theSchistosomaphylogeny. Southeast AsianSchistosoma spindaleandS. incognitumpopulations were shown to fall into their respective con-specific cohesive groupings. Estimated divergence times for these taxa were shown to be related to Pleistocene changes in sea level and the radiation of definitive host groups. A revised phylogeographical model is proposed in the light of these findings.
Collapse
Affiliation(s)
- S W Attwood
- State Key Laboratory of Biotherapy, West China Hospital, West China Medical School, Sichuan University, Chengdu 610041, PR China.
| | | | | | | | | | | | | |
Collapse
|
67
|
Abstract
As a consequence of comprehensive transcriptome analysis followed by sequencing and draft assembly of the genome, the emphasis of schistosome research is shifting from the identification of genes to the characterization of their functions and interactions. Developmental biologists have long used whole mount in situ hybridization (WISH) to determine gene expression patterns, as a vital tool for formulating and testing hypotheses about function. This paper describes the application of WISH to the study of gene expression in larval and adult schistosomes. Fixed worms were permeablized by proteinase K treatment for hybridization with digoxygenin-labelled RNA probes, with binding being detected by alkaline phosphatase-coupled anti-digoxygenin antibodies, and BM Purple substrate. Discrete staining patterns for the transcripts of the molecules Sm29, cathepsin L, antigen 10.3 and chorion were observed in the tegument cell bodies, gut epithelium, oesophageal gland and vitelline lobules, respectively, of adult worms. Transcripts of the molecules SGTP4, GP18-22 and cathepsin L were localized to tegument cell bodies and embryonic gut, respectively, of lung schistosomula. We also showed that Fast Red TR fluorescent substrate can refine the pattern of localization permitting use of confocal microscopy. We believe that method of WISH will find broad application, in synergy with other emerging post-genomic techniques, such as RNA interference, to studies focused at increasing our molecular understanding of schistosomes.
Collapse
Affiliation(s)
- G P Dillon
- Biology Department, University of York, Heslington, York YO10 5DD, UK.
| | | | | | | |
Collapse
|
68
|
Abstract
Schistosomes are multicellular parasites of humans exhibiting interesting biological adaptations to their parasitic lifestyle. Concerted and in depth analyses of these adaptations and their cell and molecular biology requires further development of molecular genetic tools in schistosomes. In the current study, we demonstrate that a Gaussia luciferase reporter leads to significantly higher levels of luciferase activity in schistosomes compared to other tested luciferases. In addition, Gaussia luciferase can be secreted into culture media enabling non-invasive analysis of reporter activity. The secretion of Gaussia luciferase should allow a variety of new experimental paradigms for schistosome studies. Comparison of biolistic and electroporation transfection methods using luciferase RNA reporters and the luciferase acitivty produced indicates that electroporation of sporocysts and schistosomula is the most efficient transfection method for the four stages analyzed. These data should facilitate additional studies in schistosomes and provide a framework for further development of DNA transfection and gene expression analysis.
Collapse
Affiliation(s)
| | - Richard E. Davis
- Address correspondence to: Dr. Richard E. Davis, Departments of Pediatrics and Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Mail Stop 8101, RC-1 South, P.O. Box 6511, 12801 East 17th Avenue, Aurora, CO 80045; Tel: 303-724-3226; Fax: 303-724-3215;
| |
Collapse
|
69
|
Jones MK, Higgins T, Stenzel DJ, Gobert GN. Towards tissue specific transcriptomics and expression pattern analysis in schistosomes using laser microdissection microscopy. Exp Parasitol 2007; 117:259-66. [PMID: 17662980 DOI: 10.1016/j.exppara.2007.06.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2007] [Revised: 06/08/2007] [Accepted: 06/09/2007] [Indexed: 12/23/2022]
Abstract
One difficulty facing post-genomic analyses of schistosomes is the limited data on sites of expression of many gene products expressed by the parasites in their hosts. The potential for use of laser microdissection microscopy as a preparative technique for transcriptional and proteomic profiling is reviewed. This technique allows tissues to be dissected for subsequent molecular and protein analysis. The method is reviewed in the light of the acoelomate triploblastic nature of tissue organisation in the parasite.
Collapse
Affiliation(s)
- Malcolm K Jones
- Queensland Institute of Medical Research, 300 Herston Road, Herston, Qld 4006, Australia.
| | | | | | | |
Collapse
|
70
|
van Hellemond JJ, van Balkom BWM, Tielens AGM. Schistosome biology and proteomics: progress and challenges. Exp Parasitol 2007; 117:267-74. [PMID: 17577589 DOI: 10.1016/j.exppara.2007.05.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2007] [Revised: 05/09/2007] [Accepted: 05/09/2007] [Indexed: 11/28/2022]
Abstract
The recent availability of schistosomal genome-sequence information allows protein identification in schistosome-derived samples by mass spectrometry (proteomics). Over the last few years, several proteome studies have been performed that addressed important questions in schistosome biology. This review summarizes the applied experimental approaches that have been used so far, it provides an overview of the most important conclusions that can be drawn from the performed studies and finally discusses future challenges in this research area.
Collapse
Affiliation(s)
- Jaap J van Hellemond
- Department of Medical Microbiology and Infectious Diseases, Erasmus MC, University Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD Rotterdam, The Netherlands.
| | | | | |
Collapse
|
71
|
Zarowiecki MZ, Huyse T, Littlewood DTJ. Making the most of mitochondrial genomes--markers for phylogeny, molecular ecology and barcodes in Schistosoma (Platyhelminthes: Digenea). Int J Parasitol 2007; 37:1401-18. [PMID: 17570370 DOI: 10.1016/j.ijpara.2007.04.014] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2007] [Revised: 04/19/2007] [Accepted: 04/24/2007] [Indexed: 11/27/2022]
Abstract
An increasing number of complete sequences of mitochondrial (mt) genomes provides the opportunity to optimise the choice of molecular markers for phylogenetic and ecological studies. This is particularly the case where mt genomes from closely related taxa have been sequenced; e.g., within Schistosoma. These blood flukes include species that are the causative agents of schistosomiasis, where there has been a need to optimise markers for species and strain recognition. For many phylogenetic and population genetic studies, the choice of nucleotide sequences depends primarily on suitable PCR primers. Complete mt genomes allow individual gene or other mt markers to be assessed relative to one another for potential information content, prior to broad-scale sampling. We assess the phylogenetic utility of individual genes and identify regions that contain the greatest interspecific variation for molecular ecological and diagnostic markers. We show that variable characters are not randomly distributed along the genome and there is a positive correlation between polymorphism and divergence. The mt genomes of African and Asian schistosomes were compared with the available intraspecific dataset of Schistosoma mansoni through sliding window analyses, in order to assess whether the observed polymorphism was at a level predicted from interspecific comparisons. We found a positive correlation except for the two genes (cox1 and nad1) adjoining the putative control region in S. mansoni. The genes nad1, nad4, nad5, cox1 and cox3 resolved phylogenies that were consistent with a benchmark phylogeny and in general, longer genes performed better in phylogenetic reconstruction. Considering the information content of entire mt genome sequences, partial cox1 would not be the ideal marker for either species identification (barcoding) or population studies with Schistosoma species. Instead, we suggest the use of cox3 and nad5 for both phylogenetic and population studies. Five primer pairs designed against Schistosoma mekongi and Schistosoma malayensis were tested successfully against Schistosoma japonicum. In combination, these fragments encompass 20-27% of the variation amongst the genomes (average total length approximately 14,000bp), thus providing an efficient means of encapsulating the greatest amount of variation within the shortest sequence. Comparative mitogenomics provides the basis of a rational approach to molecular marker selection and optimisation.
Collapse
Affiliation(s)
- M Z Zarowiecki
- Wolfson Wellcome Biomedical Laboratories, Department of Zoology, Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | | | | |
Collapse
|
72
|
Abbasi I, King CH, Sturrock RF, Kariuki C, Muchiri E, Hamburger J. Differentiation of Schistosoma haematobium from related schistosomes by PCR amplifying an inter-repeat sequence. Am J Trop Med Hyg 2007; 76:950-5. [PMID: 17488921 PMCID: PMC2254496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/15/2023] Open
Abstract
Schistosoma haematobium infects nearly 150 million people, primarily in Africa, and is transmitted by select species of local bulinid snails. These snails can host other related trematode species as well, so that effective detection and monitoring of snails infected with S. haematobium requires a successful differentiation between S. haematobium and any closely related schistosome species. To enable differential detection of S. haematobium DNA by simple polymerase chain reaction (PCR), we designed and tested primer pairs from numerous newly identified Schistosoma DNA repeat sequences. However, all pairs tested were found unsuitable for this purpose. Differentiation of S. haematobium from S. bovis, S. mattheei, S. curassoni, and S. intercalatum (but not from S. margrebowiei) was ultimately accomplished by PCR using one primer from a newly identified repeat, Sh110, and a second primer from a known schistosomal splice-leader sequence. For evaluation of residual S. haematobium transmission after control interventions, this differentiation tool will enable accurate monitoring of infected snails in areas where S. haematobium is sympatric with the most prevalent other schistosome species.
Collapse
Affiliation(s)
- Ibrahim Abbasi
- Kuvin Center, Hebrew University, Hadassah Medical School, Jerusalem, Israel.
| | | | | | | | | | | |
Collapse
|
73
|
Abstract
In contrast to the situations with model organisms and parasitic protozoa, progress with gene manipulation with schistosomes has been delayed by impediments that include our inability to maintain the life cycle in vitro, absence of immortalized cell lines, large genome sizes, unavailability of drug resistance markers and other difficulties. However, in the past few years, tangible progress has been reported towards development of tools for gene manipulation and transgenesis of schistosomes, and there is reason to believe that the field is on the verge of transformation into an era where genetic manipulation is routine. Recent reports dealing with approaches and tools to manipulate the genome and gene expression in schistosomes are reviewed here.
Collapse
Affiliation(s)
- Paul J Brindley
- Department of Tropical Medicine, Tulane University Health Sciences Center, New Orleans, Louisiana 70112, USA.
| | | |
Collapse
|
74
|
Kalinna BH, Brindley PJ. Manipulating the manipulators: advances in parasitic helminth transgenesis and RNAi. Trends Parasitol 2007; 23:197-204. [PMID: 17383233 DOI: 10.1016/j.pt.2007.03.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Revised: 02/01/2007] [Accepted: 03/12/2007] [Indexed: 01/26/2023]
Abstract
Because tropical medicine and parasitology research has moved into the postgenomic era, an enormous amount of gene sequence information for parasitic helminths is now accumulating. These sequences undoubtedly hold information that can be used for new interventions and control. However, to exploit the new resource, methods for gene manipulation and transformation of parasitic worms are needed. Until recently, gene manipulation approaches had not been seriously addressed. This situation is now changing in response to the availability of genome sequences and other advances. In this article, we review advances in the transgenesis and gene silencing of parasitic worms.
Collapse
Affiliation(s)
- Bernd H Kalinna
- Centre for Animal Biotechnology, Faculty of Veterinary Science, The University of Melbourne, Parkville, 3010 VIC, Australia.
| | | |
Collapse
|
75
|
Abstract
Past and more recent research has examined the ultrastructure, metabolism, cell biology, genomics and post-genomics of schistosome schistosomula. These areas are considered and discussed in this review with particular emphasis on (1) the early migration phases through the host, (2) interaction of the host immune response with the parasite surface, (3) glucose uptake mechanisms, and (4) defining the transcriptional profiles of lung-stage schistosomula compared with other developmental stages using microarrays. The microarray profiling studies suggest caution is required when considering the use of schistosomes obtained by in vitro means for molecular or biochemical studies.
Collapse
Affiliation(s)
- G N Gobert
- Molecular Parasitology Laboratory, Infectious Diseases and Immunology Division, The Queensland Institute of Medical Research, 300 Herston Road, Brisbane, Queensland 4006 Australia.
| | | | | |
Collapse
|
76
|
Wilson RA, Ashton PD, Braschi S, Dillon GP, Berriman M, Ivens A. 'Oming in on schistosomes: prospects and limitations for post-genomics. Trends Parasitol 2006; 23:14-20. [PMID: 17097923 DOI: 10.1016/j.pt.2006.10.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Revised: 10/18/2006] [Accepted: 10/24/2006] [Indexed: 11/30/2022]
Abstract
The recent release of version 3 of the Schistosoma mansoni genome assembly has made a wealth of information available to researchers. Here, progress made in schistosome genomics and post-genomics is considered. The current status of knowledge about the genome, transcriptome, proteome, glycome and immunome is summarized and recent publications briefly reviewed. The prospects for advances in understanding schistosome biology are highlighted. Most importantly, the limitations (which are mostly technical) that need to be addressed before the full potential of the genome database(s) can be realized are emphasized.
Collapse
Affiliation(s)
- R Alan Wilson
- Department of Biology, University of York, PO Box 373, York YO10 5YW, UK.
| | | | | | | | | | | |
Collapse
|
77
|
Abstract
The present work is a contribution to the systematics of Bilhorziello and Dendritobilharzio. Wildfowl was killed in hunting seasons or found dead in Champagne-Ardenne region, France, and autopsied with focus on schistosomes. Seven Anas plotyrhynchos (mallards), one Ardeo cinerea (grey heron) and two Cygnus olor (mute swans) were parasitized by Bilharziella. One C. olor was parasitized by Dendritobilharzia. Depending on season and hosts, various morphological forms of Bilharziello suggesting several species were observed. The differences in male and female worms concerned the morphology of genital apparatus, the spination on suckers, the body size and proportions. However, the comparison of DNA sequences led to a conclusion that these forms belonged to one species, Bilharziella polonica (Kowalewski, 1895). The morphological features and the body sizes of our samples of Dendritobilharzia seemed to differ from the type species of D. pulverulenta (Braun, 1901). Nevertheless, molecular analysis confirmed identity. We hypothesize that the differences in Bilharziella and Dendritobilharzia might be linked to internal host factors (e.g. hormonal levels), and influenced by season, host, and worm age. The definition of the genera Bilharziello and Dendritobilharzio was amended.
Collapse
Affiliation(s)
- C Bayssade-Dufour
- USM 602, Biologie parasitaire, Systématique et Evolution, MNHN, 61, rue Buffon,75231 Paris, France
| | | | | | | | | |
Collapse
|
78
|
Webster BL, Tchuem Tchuenté LA, Southgate VR. A single-strand conformation polymorphism (SSCP) approach for investigating genetic interactions of Schistosoma haematobium and Schistosoma guineensis in Loum, Cameroon. Parasitol Res 2006; 100:739-45. [PMID: 17058111 DOI: 10.1007/s00436-006-0310-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2006] [Accepted: 08/08/2006] [Indexed: 11/30/2022]
Abstract
Single-strand conformation polymorphism (SSCP) analysis of the second internal transcribed spacer (ITS2) of nuclear ribosomal DNA provides a molecular tool for the identification of Schistosoma haematobium, Schistosoma guineensis and the hybrids of these two species. This molecular tool was utilized to provide a detailed analysis of the interactions between S. haematobium and S. guineensis in hybrid zones of Loum, Littoral Province, Cameroon. Individual hybrid schistosomes were identified within the natural populations collected from Loum in 1990, 1999 and 2000, which would have been misidentified as S. haematobium using solely morphological and sequence criteria. This study indicates the complexities of the hybridization between S. haematobium and S. guineensis and emphasizes the importance of assessing morphological, biological and molecular data to gain insights into the interaction of these two species over time.
Collapse
Affiliation(s)
- B L Webster
- Wolfson Wellcome Biomedical Laboratories, Department of Zoology, The Natural History Museum, Cromwell Road, South Kensington London, SW7 5BD, UK.
| | | | | |
Collapse
|
79
|
Copeland CS, Lewis FA, Brindley PJ. Identification of the Boudicca and Sinbad retrotransposons in the genome of the human blood fluke Schistosoma haematobium. Mem Inst Oswaldo Cruz 2006; 101:565-71. [PMID: 17072464 DOI: 10.1590/s0074-02762006000500015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2006] [Accepted: 06/08/2006] [Indexed: 11/22/2022] Open
Abstract
Schistosomes have a comparatively large genome, estimated for Schistosoma mansoni to be about 270 megabase pairs (haploid genome). Recent findings have shown that mobile genetic elements constitute significant proportions of the genomes of S. mansoni and S. japonicum. Much less information is available on the genome of the third major human schistosome, S. haematobium. In order to investigate the possible evolutionary origins of the S. mansoni long terminal repeat retrotransposons Boudicca and Sinbad, several genomes were searched by Southern blot for the presence of these retrotransposons. These included three species of schistosomes, S. mansoni, S. japonicum, and S. haematobium, and three related platyhelminth genomes, the liver flukes Fasciola hepatica and Fascioloides magna and the planarian, Dugesia dorotocephala. In addition, Homo sapiens and three snail host genomes, Biomphalaria glabrata, Oncomelania hupensis, and Bulinus truncatus, were examined for possible indications of a horizontal origin for these retrotransposons. Southern hybridization analysis indicated that both Boudicca and Sinbad were present in the genome of S. haematobium. Furthermore, low stringency Southern hybridization analyses suggested that a Boudicca-like retrotransposon was present in the genome of B. truncatus, the snail host of S. haematobium.
Collapse
Affiliation(s)
- Claudia S Copeland
- United States Department of Agriculture, Associated Research Service, Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, FL, USA.
| | | | | |
Collapse
|
80
|
Sandoval N, Siles-Lucas M, Pérez-Arellano JL, Carranza C, Puente S, López-Abán J, Muro A. A new PCR-based approach for the specific amplification of DNA from different Schistosoma species applicable to human urine samples. Parasitology 2006; 133:581-7. [PMID: 16834820 DOI: 10.1017/s0031182006000898] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2006] [Revised: 05/02/2006] [Accepted: 06/05/2006] [Indexed: 12/14/2022]
Abstract
Currently available methods for the diagnosis of human schistosomiasis often lack enough sensitivity and specificity. Recently, several authors have developed more specific and sensitive diagnostic methods, mainly based on the polymerase chain reaction (PCR) technique. Nevertheless, these have been only applied for the diagnosis of 1 out of 4 Schistosoma species affecting man (S. mansoni). Additionally, application of specific PCR has been exclusively used for blood or faecal patients' samples. Here, we develop a new, high sensitive PCR approach that allows the genus- and species-specific amplification of the main 4 Schistosoma species causing disease in man plus S. bovis. We further successfully apply this technique for the detection of parasite DNA in easy-to-handle urine samples from patients with schistosomiasis. With these samples, we have found 94.4% sensitivity and 99.9% specificity when applying a genus-specific (Schistosoma spp.) primer pair, and 100% sensitivity and 98.9% specificity in a species-specific (S. mansoni) PCR.
Collapse
Affiliation(s)
- N Sandoval
- Laboratorio de Inmunología y Parasitología Molecular, CISET, Facultad de Farmacia, Universidad de Salamanca. Avda. Campo Charro, s/n. 37007-Salamanca, Spain
| | | | | | | | | | | | | |
Collapse
|
81
|
Webster BL, Southgate VR, Littlewood DTJ. A revision of the interrelationships of Schistosoma including the recently described Schistosoma guineensis☆. Int J Parasitol 2006; 36:947-55. [PMID: 16730013 DOI: 10.1016/j.ijpara.2006.03.005] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2005] [Revised: 03/10/2006] [Accepted: 03/21/2006] [Indexed: 11/30/2022]
Abstract
In light of the recently described human schistosome Schistosoma guineensis and recent phylogenetic studies of the genus Schistosoma, a revision of the interrelationships of the members of this genus is needed. This paper adds to previous phylogenetic studies on the family Schistosomatidae and offers the most up to date and robust phylogeny of the group based on complete small and large nuclear subunit rRNA genes and partial mitochondrial cox1, incorporating most of the 21 species of Schistosoma. Our findings show that the group retains the same topology as that resolved in previous studies except Schistosoma margrebowiei was resolved as the sister taxon to all others in the Schistosoma haematobium species group and S. guineensis was placed as sister species to both Schistosoma bovis and Schistosoma curassoni. The S. haematobium species group contains eight species of which many are of significant medical and veterinary importance. Additionally, many of these species have been shown to hybridise both in the wild and experimentally, making the correct identification and recognition of species very important. A pairwise comparison of cox1 among Schistosoma species suggests this gene alone would fail as a reliable barcode for species identification. Phylogenetic results clearly treat Schistosoma intercalatum and S. guineensis as separate taxa with each more closely related evolutionarily to S. haematobium than to each other. The study also highlights the problems associated with wrongly attributed sequences on public databases such as GenBank.
Collapse
Affiliation(s)
- Bonnie L Webster
- Department of Zoology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | | | | |
Collapse
|
82
|
Kolárová L, Rudolfová J, Hampl V, Skírnisson K. Allobilharzia visceralis gen. nov., sp. nov. (Schistosomatidae-Trematoda) from Cygnus cygnus (L.) (Anatidae). Parasitol Int 2006; 55:179-86. [PMID: 16627001 DOI: 10.1016/j.parint.2005.10.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2005] [Revised: 09/06/2005] [Accepted: 10/18/2005] [Indexed: 10/24/2022]
Abstract
In Iceland, the examination of whooper swans (Cygnus cygnus L.) viscera resulted in the detection of adult digenean flukes of the family Schistosomatidae. The mature worms occurring in the blood vessels of the large intestine and mesenterium caused vascular lesions, around the eggs deposited in the intestinal mucosa and liver granulomatous reactions developed. The morphology of the isolated schistosomes shows certain similarity with the flukes of the genus Trichobilharzia; in males reduced gynecophoral canal, and on both sexes both suckers and spatulate ends are present. However, the Icelandic flukes possess other morphological features which are distinct from the genus: the point of caecal reunion in males takes place posterior to gynecophoral canal and the genital pore is behind acetabulum and anterior to caecal reunion. In order to evaluate the identity of Icelandic schistosomes, sequencing of ITS region of DNA was performed, and the obtained sequence was deposited in GenBank under the accession no. DQ067561. Following phylogenetic analysis of relationship between the sequence of Icelandic flukes and database sequences of other bird schistosome genera (Trichobilharzia, Gigantobilharzia and Dendritobilharzia) showed different position of Icelandic worms in the phylogenetic tree. In conclusion, our study revealed new genus and species of schistosome flukes--Allobilharzia visceralis gen. et sp. n.
Collapse
Affiliation(s)
- Libuse Kolárová
- National Reference Laboratory for Tissue Helminthoses, Department of Microbiology, Institute for Postgradual Medical Education and 3rd Faculty of Medicine, Charles University, Ruská 85, 100 05 Prague 10, Czech Republic.
| | | | | | | |
Collapse
|
83
|
Xu D, Curtis J, Feng Z, Minchella DJ. On the Role of Schistosome Mating Structure in the Maintenance of Drug-resistant Strains. Bull Math Biol 2006; 68:209-29. [PMID: 16794928 DOI: 10.1007/s11538-005-9001-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2004] [Accepted: 01/20/2005] [Indexed: 10/24/2022]
Abstract
The effects of drug treatment of human hosts on a population of schistosome parasites depends on a variety of factors. Previous models have shown that multiple strains of drug-resistant parasites are likely to be favored as the treatment rate increases. However, such models have neglected to account for the complex nature of schistosome mating biology. To more accurately account for the biology of these parasites, a simple mating structure is included in a multi-strain schistosome model, with parasites under the influence of drug treatment of their human hosts. Parasites are assumed to pay a cost for drug resistance in terms of reduced reproduction and transmission. The dynamics of the parasite population are described by a system of homogeneous differential equations, and the existence and stability of the exponential solutions for this system are used to infer the impact of drug treatment on the maintenance of schistosome genetic diversity.
Collapse
Affiliation(s)
- Dashun Xu
- Department of Mathematics, Purdue University, West Lafayette, IN 47907, USA.
| | | | | | | |
Collapse
|
84
|
Abstract
Interactions between schistosomes are complex with some different species being able to mate and hybridize. The epidemiology of schistosomiasis in specific areas of South West Cameroon has evolved remarkably over 30 years as a result of hybridization between Schistosoma guineensis and S. haematobium. Morphological and biological data suggest that S. haematobium replaced S. guineensis in areas of Cameroon through introgressive hybridization. Data are reported on the use of single stranded conformational polymorphism (SSCP) analysis of the nuclear ribosomal second internal transcribed spacer (ITS2) of individual schistosomes from hybrid zones of Cameroon. The data show that since 1990 S. haematobium has completely replaced S. guineensis in Loum, with S. haematobium and the recombinants still present in 2000. This study illustrates the complexities of the dynamics between S. haematobium and S. guineensis in South West Cameroon.
Collapse
Affiliation(s)
- B L Webster
- Biomedical Parasitology Division, Wolfson Wellcome Biomedical Laboratories, Department of Zoology, The Natural History Museum, South Kensington, London SW7 5BD, UK.
| | | | | | | |
Collapse
|
85
|
Littlewood DTJ, Lockyer AE, Webster BL, Johnston DA, Le TH. The complete mitochondrial genomes of Schistosoma haematobium and Schistosoma spindale and the evolutionary history of mitochondrial genome changes among parasitic flatworms. Mol Phylogenet Evol 2006; 39:452-67. [PMID: 16464618 DOI: 10.1016/j.ympev.2005.12.012] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2005] [Revised: 12/20/2005] [Accepted: 12/23/2005] [Indexed: 11/28/2022]
Abstract
Complete mitochondrial genome sequences for the schistosomes Schistosoma haematobium and Schistosoma. spindale have been characterized. S. haematobium is the causative agent of urinary schistosomiasis in humans and S. spindale uses ruminants as its definitive host; both are transmitted by freshwater snail intermediate hosts. Results confirm a major gene order rearrangement among schistosomes in all traditional Schistosoma species groups other than Schistosoma japonicum; i.e., species groups S. mansoni, S. haematobium, and S. indicum. These data lend support to the 'out of Asia' (East and Southeast Asia) hypothesis for Schistosoma. The gene order change involves translocation of atp6-nad2-trnA and a rearrangement of nad3-nad1 relative to other parasitic flatworm mt genomes so far sequenced. Gene order and tRNA secondary structure changes (loss and acquisition of the DHU and/or TPsiC arms of trnC, trnF, and trnR) between mitochondrial genomes of these and other (digenean and cestode) flatworms were inferred by character mapping onto a phylogeny estimated from nuclear small subunit rRNA gene sequences of these same species, in order to find additional rare genomic changes suitable as synapomorphies. Denser and wider taxon sampling of mt genomes across the Platyhelminthes will validate these putative characters.
Collapse
|
86
|
Abstract
Twenty years ago, an article by Carter and Colley was published in an early issue of this journal. The report outlined pioneering studies by several laboratories into schistosome molecular biology and molecular genetics. To commemorate that prescient report and, in like fashion, to provide a brief (and non-comprehensive) synopsis of progress in this field up to the present time, I will outline some key aspects of the molecular biology of schistosomes that have been reported in the intervening years.
Collapse
Affiliation(s)
- Paul J Brindley
- Department of Tropical Medicine and Center for Infectious Diseases, Tulane University, Health Sciences Center, New Orleans, LA 70112, USA.
| |
Collapse
|
87
|
Abstract
Horizontal gene transfer (HGT), in relation to genetic transfer between hosts and parasites, is a little described mechanism. Since the complement inhibitor CRIT was first discovered in the human Schistosoma parasite (the causative agent of Bilharzia) and in Trypanosoma cruzi (a parasite causing Chagas' disease), it has been found to be distributed amongst various species, ranging from the early teleost cod to rats and humans. In terms of evolutionary distance, as measured in a phylogenetic analysis of these CRIT genes at nucleotide level, the parasitic species are as removed from their human host as is the rat sequence, suggesting HGT. The hypotheses that CRIT in humans and schistosomes is orthologous and that the presence of CRIT in schistosomes occurs as a result of host-to-parasite HGT are presented in the light of empirical data and the growing body of data on mobile genetic elements in human and schistosome genomes. In summary, these data indicate phylogenetic proximity between Schistosoma and human CRIT, identity of function, high nucleotide/amino acid identity and secondary protein structure, as well as identical genomic organization.
Collapse
Affiliation(s)
- Jameel M Inal
- Immunonephrology, Department of Research, University Hospital Basel, Basel, Switzerland.
| |
Collapse
|
88
|
Li Y, Tao K, Jin H, Zhang J, Cao M, Zhou J, Tang Y, Zhu J, Guo H. Design and development of a DNA array for rapid detection and genotyping of seven kinds of pathogenic microbes. J Nanosci Nanotechnol 2005; 5:1220-4. [PMID: 16193981 DOI: 10.1166/jnn.2005.215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
A DNA array for rapid detection and genotyping of the pathogenic microbes of epidemic hemorrhagic fever, tsutsugamushi disease, leptospirosis, malaria, schistosomiasis, cholera, and hemorrhagic colitis was developed. The specific and relatively conserved PCR primers and DNA probes were screened from the characteristic genes of the pathogenic microbes. The PCR or RT-PCR methods were established for amplifying and labeling the DNA fragments of the pathogenic microbes. All the probes with the same Tm value were synthesized chemically and modified with an NH2 at their 5' terminus, they were printed on glass slides for fabrication of a oligonucleotide DNA array. The developed DNA array could be used for detecting and genotyping the pathogenic microbes simultaneously, and they had a high sensitivity and specificity.
Collapse
Affiliation(s)
- Yuexi Li
- East-China Institute of Medicine and Biotechniques, Nanjing 210002, P R. China
| | | | | | | | | | | | | | | | | |
Collapse
|
89
|
Guo J, Guo JG. [Research progress of the evaluation methods on the resistance of schistosome to praziquantel]. Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi 2005; 23:182-4. [PMID: 16300016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
|
90
|
Prugnolle F, Roze D, Théron A, DE Meeûs T. F-statistics under alternation of sexual and asexual reproduction: a model and data from schistosomes (platyhelminth parasites). Mol Ecol 2005; 14:1355-65. [PMID: 15813776 DOI: 10.1111/j.1365-294x.2005.02541.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Accurate inferences on population genetics data require a sound underlying theoretical null model. Nearly nothing is known about the gene dynamics of organisms with complex life cycles precluding any biological interpretation of population genetics parameters. In this article, we used an infinite island model to derive the expectations of those parameters for the life cycle of a dioecious organism obligatorily alternating sexual and asexual reproductions as it is the case for schistosomes (plathyhelminth parasites). This model allowed us to investigate the effects of the degree of mixing among individuals coming from different subpopulations at each new generation (represented in the model by the migration rates before and after clonal reproductions) and the variance in the reproductive success of individuals during the clonal phase. We also consider the effects of different migration rates and degrees of clonal reproductive skew between male and female individuals. Results show that the variance in the reproductive success of clones is very important in shaping the distribution of the genetic variability both within and among subpopulations. Thus, higher variance in the reproductive success of clones generates heterozygous excesses within subpopulations and also increases genetic differentiation between them. Migration occurring before and after asexual reproduction has different effects on the patterns of F(IS) and F(ST). When males and females display different degrees of reproductive skew or migration rates, we observe differences in their respective population genetic structure. While results of the model apply to any organism alternating sexual and clonal reproductions (e.g. all parasitic trematodes, many plants, and all aphididae), we finally confront some of these theoretical expectations to empirical data from Schistosoma mansoni infecting Rattus rattus in Guadeloupe.
Collapse
Affiliation(s)
- Franck Prugnolle
- Equipe ESS, GEMI, UMR-2724, IRD de Montpellier, 911 av. Agropolis, BP 64501, 34394 Montpellier cedex 5, France.
| | | | | | | |
Collapse
|
91
|
Bentley GN, Jones AK, Agnew A. Expression and comparative functional characterisation of recombinant acetylcholinesterase from three species of Schistosoma. Mol Biochem Parasitol 2005; 141:119-23. [PMID: 15811534 DOI: 10.1016/j.molbiopara.2005.01.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2004] [Accepted: 01/21/2005] [Indexed: 11/20/2022]
Affiliation(s)
- Geoffrey N Bentley
- The School of Biology, University of Leeds, Leeds, West Yorkshire LS2 9JT, UK.
| | | | | |
Collapse
|
92
|
Aksoy E, Zouain CS, Vanhoutte F, Fontaine J, Pavelka N, Thieblemont N, Willems F, Ricciardi-Castagnoli P, Goldman M, Capron M, Ryffel B, Trottein F. Double-stranded RNAs from the Helminth Parasite Schistosoma Activate TLR3 in Dendritic Cells. J Biol Chem 2005; 280:277-83. [PMID: 15519998 DOI: 10.1074/jbc.m411223200] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Stimulation of dendritic cells (DCs) by the egg stage of the helminth parasite Schistosoma mansoni activates a signaling pathway resulting in type I interferon (IFN) and IFN-stimulated gene (ISG) expression. Here, we demonstrate that S. mansoni eggs disjointedly activate myeloid differentiation factor 88 (MyD88)-dependent and MyD88-independent pathways in DCs. Inflammatory cytokine expression and NF-kappa B activation in DCs from MyD88-deficient mice were impaired, whereas signaling transducer activator of transcription (STAT) 1(Tyr701) phosphorylation and ISG expression were intact in MyD88 or Toll-like receptor (TLR)4-deficient counterparts. Accordingly, we analyzed distinct TLR members for their ability to respond to schistosome eggs and established that TLR3 resulted in the activation of NF-kappa B and the positive regulatory domain III-I site from IFN-beta promoter. Unexpectedly, egg-derived RNA possessed RNase A-resistant and RNase III-sensitive structures capable of triggering TLR3 activation, suggesting the involvement of double-stranded (ds) structures. Moreover, DCs from TLR3-deficient mice displayed a complete loss of signaling transducer activator of transcription 1 phosphorylation and ISG expression in response to egg-derived dsRNA. Finally, TLR3-deficient DCs showed a reduced response to schistosome eggs relative to wild-type cells. Collectively, our data suggest for the first time that dsRNA from a non-viral pathogen may act as an inducer of the innate immune system through TLR3.
Collapse
Affiliation(s)
- Ezra Aksoy
- INSERM U547, Institut Pasteur de Lille, Lille 59019, France
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
93
|
Abstract
PURPOSE OF REVIEW Schistosomiasis is an important poverty-related health problem and more than 200 million people are infected. This review summarizes papers from April 2003 to June 2004 with a focus on schistosomiasis morbidity and the various factors that affect the level of morbidity in endemic populations. The aim is to provide an update on the current state of knowledge and, hopefully, thereby stimulate continued research interest in this important area. RECENT FINDINGS Research into the immune responses associated with severe morbidity has provided new insights into the mechanisms of immune regulation as well as the role of genetic predisposition to periportal fibrosis. Malaria and schistosomiasis are co-endemic and co-infection with malaria may increase the level of morbidity in hepatosplenic schistosomiasis, and alter the host immune response towards schistosome antigens. Schistosome infections may render the host more susceptible to human immunodeficiency virus infection by either interfering with immune responses or increasing the risk of transmission due to genital lesions. An important advance in schistosomiasis research, and parasite genomics, is the recent availability of two major Schistosoma mansoni and Schistosoma japonicum DNA bioinformatic resources. SUMMARY Significant advances have been achieved in our understanding of the epidemiology, immunology and genetics of schistosomiasis, and the various factors that may influence morbidity. However, good research is vital for sustainable disease control, and continued progress requires a critical mass of researchers with a range of expertise from basic parasite biology to public-health interventions. It is therefore important to strengthen research capacity in endemic countries.
Collapse
|
94
|
|
95
|
Abstract
The hammerhead ribozyme is a small RNA motif that catalyzes the cleavage and ligation of RNA. The well-studied minimal hammerhead motif is inactive under physiological conditions and requires high Mg(2+) concentrations for efficient cleavage. In contrast, natural hammerheads are active under physiological conditions and contain motifs outside the catalytic core that lower the requirement for Mg(2+). Single-turnover kinetics were used here to characterize the Mg(2+) and pH dependence for cleavage of a trans-cleaving construct of the Schistosoma mansoni natural hammerhead ribozyme. Compared to the minimal hammerhead motif, the natural Schistosoma ribozyme requires 100-fold less Mg(2+) to achieve a cleavage rate of 1 min(-1). The improved catalysis results from tertiary interactions between loops in stems I and II and likely arises from increasing the population of the active conformation. Under optimum pH and Mg(2+) conditions this ribozyme cleaves at over 870 min(-1) at 25 degrees C, further demonstrating the impressive catalytic power of this ribozyme.
Collapse
Affiliation(s)
- Marella D Canny
- Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, CO 80309-0215, USA
| | | | | | | | | | | |
Collapse
|
96
|
Abstract
Schistosomiasis is one of the most serious parasitic diseases. More than 250 million people are infected with schistosomes in the tropics or subtropics. The parasitic flukes have some unique biological features: dioecism, complex life cycles, mechanisms to avoid host immune responses, and an apparent reliance on host endocrine and immune signals to complete their development, maturation and egg production. Recently, a large dataset of expressed sequence tags (ESTs) were generated from Schistosoma japonicum and Schistosoma mansoni, from which numerous novel genes were identified. The transcriptome analyses provide the basis for a comprehensive understanding of the molecular mechanisms involved in schistosome nutrition and metabolism, host-dependent development and maturation, immune evasion and invertebrate evolution. In addition, new potential vaccine candidates and drug targets have been predicted.
Collapse
Affiliation(s)
- Wei Hu
- Department of Tropical Medicine, Tulane University Health Sciences Center, New Orleans, LA 70112, USA
| | | | | | | | | |
Collapse
|
97
|
McCarthy E, Stack C, Donnelly SM, Doyle S, Mann VH, Brindley PJ, Stewart M, Day TA, Maule AG, Dalton JP. Leucine aminopeptidase of the human blood flukes, Schistosoma mansoni and Schistosoma japonicum. Int J Parasitol 2004; 34:703-14. [PMID: 15111092 DOI: 10.1016/j.ijpara.2004.01.008] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2003] [Revised: 01/28/2004] [Accepted: 01/29/2004] [Indexed: 10/26/2022]
Abstract
An array of schistosome endoproteases involved in the digestion of host hemoglobin to absorbable peptides has been described, but the exoprotease responsible for catabolising these peptides to amino acids has yet to be identified. By searching the public databases we found that Schistosoma mansoni and Schistosoma japonicum express a gene encoding a member of the M17 family of leucine aminopeptidases (LAPs). A functional recombinant S. mansoni LAP produced in insect cells shared biochemical properties, including pH optimum for activity, substrate specificity and reliance on metal cations for activity, with the major aminopeptidase activity in soluble extracts of adult worms. The pH range in which the enzyme functions and the lack of a signal peptide indicate that the enzyme functions intracellularly. Immunolocalisation studies showed that the S. mansoni LAP is synthesised in the gastrodermal cells surrounding the gut lumen. Accordingly, we propose that peptides generated in the lumen of the schistosome gut are absorbed into the gastrodermal cells and are cleaved by LAP to free amino acids before being distributed to the internal tissues of the parasite. Since LAP was also localised to the surface tegument it may play an additional role in surface membrane re-modelling.
Collapse
Affiliation(s)
- Elaine McCarthy
- Molecular Parasitology Unit, School of Biotechnology, Dublin City University, Dublin 9, Ireland
| | | | | | | | | | | | | | | | | | | |
Collapse
|
98
|
Abstract
Although we live in what is often touted as the 'post-genomic era', this term is hardly appropriate when we consider the paucity of knowledge of the genomic biology of parasitic flatworms. The situation is, however, changing-at least for two species of Schistosoma. Recent transcriptome analysis of Schistosoma mansoni and of Schistosoma japonicum has identified novel genes and genes not previously reported for schistosomes, as well as the identification of the molecular mechanisms for host-dependent maturation, immune evasion, development, signalling and sexual dimorphism. The analyses also identify potential vaccine candidates and drug targets. Here, the current state of knowledge is reviewed for mitochondrial and nuclear genomes of parasitic flatworms. We highlight the remarkable recent progress in gene discovery for schistosomes and the goal of sequencing complete schistosome genomes.
Collapse
Affiliation(s)
- Donald P McManus
- Australian Centre for International and Tropical Health and Nutrition, The Queensland Institute of Medical Research and The University of Queensland, Brisbane, Qld 4029, Australia.
| | | | | |
Collapse
|
99
|
|
100
|
Liang Y, Xiao JH. [Current status and prospects of the research on sex-specific gene of schistosomes]. Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi 2004; 20:183-6. [PMID: 12568006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
|