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Dell A, Haslam SM, Morris HR, Khoo KH. Immunogenic glycoconjugates implicated in parasitic nematode diseases. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1455:353-62. [PMID: 10571024 DOI: 10.1016/s0925-4439(99)00064-2] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Parasitic nematodes infect billions of people world-wide, often causing chronic infections associated with high morbidity. The greatest interface between the parasite and its host is the cuticle surface, the outer layer of which in many species is covered by a carbohydrate-rich glycocalyx or cuticle surface coat. In addition many nematodes excrete or secrete antigenic glycoconjugates (ES antigens) which can either help to form the glycocalyx or dissipate more extensively into the nematode's environment. The glycocalyx and ES antigens represent the main immunogenic challenge to the host and could therefore be crucial in determining if successful parasitism is established. This review focuses on a few selected model systems where detailed structural data on glycoconjugates have been obtained over the last few years and where this structural information is starting to provide insight into possible molecular functions.
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Affiliation(s)
- A Dell
- Department of Biochemistry, Imperial College of Science Technology and Medicine, London, UK.
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103
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Gentner JM, Wentrup-Byrne E. Natural history specimen analysis using micro FT-IR attenuated total reflectance spectroscopy and transmission electron microscopy. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 1999; 55A:2281-2288. [PMID: 10581739 DOI: 10.1016/s1386-1425(99)00094-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A combination of micro Fourier transform infrared (FT-IR) attenuated total reflectance (ATR) spectroscopy and transmission electron microscopy (TEM) provided a complete analysis of the interaction between nematode cuticle structure and preservation fluids. Spectroscopic results were successfully correlated with TEM results. While fresh nematode cuticle yielded uniform spectra, damaged cuticles were characterised by large spectrum to spectrum variations in the 1000-1100 cm-1 region. An important outcome of this investigation was the demonstrated potential of micro FT-IR ATR as a technique for the analysis of challenging natural history samples.
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Affiliation(s)
- J M Gentner
- Centre for Instrumental and Developmental Chemistry, Queensland University of Technology, Brisbane, Australia
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104
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Abstract
Caenorhabditis elegans is a rhabditid nematode. What relevance does this have for the interpretation of the complete genome sequence, and how will it affect the exploitation of the sequence for scientific and social ends? Nematodes are only distantly related to humans and other animal groups; will this limit the universality of the C. elegans story? Many nematodes are parasites; can knowledge of the C. elegans sequence aid in the prevention and treatment of disease?
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Affiliation(s)
- M Blaxter
- Institute of Cell, Animal, and Population Biology, University of Edinburgh, Edinburgh EH9 3JT, UK
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105
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Joachim A, Ruttkowski B, Daugschies A. Changes in antigen and glycoprotein patterns during the development of Oesophagostomum dentatum. Int J Parasitol 1998; 28:1853-60. [PMID: 9925263 DOI: 10.1016/s0020-7519(98)00163-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
During its development from free-living infectious third-stage larvae to the adult worms in the large intestines of pigs, Oesophagostomum dentatum experiences several environmental changes. Differences in protein patterns can reflect such changes. Somatic and ES antigens and glycoproteins of pre-parasitic, histotropic and intestinal stages were compared by single-dimension SDS-PAGE and stage-specific proteins were defined. Furthermore, fourth-stage larvae derived from different sources--in-vitro cultivation and intestinal contents--were compared and also found to be different. It is hypothesised that O. dentatum reacts to environmental stimuli by differential expression of specific proteins as a possible mode of adaptation to the host.
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Affiliation(s)
- A Joachim
- Institute of Parasitology, Hannover School of Veterinary Medicine, Germany
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106
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Abstract
Caenorhabditis elegans has become a popular model system for genetic and molecular research, since it is easy to maintain and has a very fast life-cycle. Its genome is small and a virtually complete physical map in the form of cosmids and YAC clones exists. Thus it was chosen as a model system by the Genome Project for sequencing, and it is expected that by 1998 the complete sequence (100 million bp) will be available. The accumulated wealth of information about C. elegans should be a boon for nematode parasitologists, as many aspects of gene regulation and function can be studied in this simple model system. A large array of techniques is available to study many aspects of C. elegans biology. In combination with genome projects for parasitic nematodes, conserved genes can be identified rapidly. We expect many new areas of fertile research that will lead to new insights in helminth parasitology, which are based not only on the information gained from C. elegans per se, but also from its use as a heterologous system to study parasitic genes.
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Affiliation(s)
- T R Bürglin
- Department of Cell Biology, Biozentrum, University of Basel, Switzerland.
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107
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Martinez AM, De Souza W. A freeze-fracture and deep-etch study of the cuticle and hypodermis of infective larvae of Strongyloides venezuelensis (Nematoda). Int J Parasitol 1997; 27:289-97. [PMID: 9138031 DOI: 10.1016/s0020-7519(96)00172-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The body walls of infective 3rd-stage larvae of S. venezuelensis were studied by routine transmission electron microscopy, ruthenium red cytochemistry, quick-freeze, freeze-fracture and deep-etch techniques. In routine thin sections the cuticle is formed by 5 layers: epicuticle, cortical, medial, fibrous and basal. The epicuticle showed a trilaminate appearance and a surface coat stained with ruthenium red. Specimens submitted to freeze-fracture were frequently sectioned along the body wall at the level of the hypodermis, showing the E and P fracture faces of the outer and inner hypodermal membranes. In replicas of fractures submitted to etching, the external surface of the nematode was exposed, revealing particles and fine strands of fibrous elements, and was sometimes covered by a well organized structure with a crystalline pattern. At the level of the cortical, medial and basal layers, interconnecting fibrous and globous structures were seen. The fibrous layer was formed by parallel bars of thick fibrous elements. The cytoskeleton of the hypodermis and muscle cells also became evident with this technique.
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Affiliation(s)
- A M Martinez
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brasil
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108
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Grenache DG, Caldicott I, Albert PS, Riddle DL, Politz SM. Environmental induction and genetic control of surface antigen switching in the nematode Caenorhabditis elegans. Proc Natl Acad Sci U S A 1996; 93:12388-93. [PMID: 8901591 PMCID: PMC38001 DOI: 10.1073/pnas.93.22.12388] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Nematodes can alter their surface coat protein compositions at the molts between developmental stages or in response to environmental changes; such surface alterations may enable parasitic nematodes to evade host immune defenses during the course of infection. Surface antigen switching mechanisms are presently unknown. In a genetic study of surface antigen switching, we have used a monoclonal antibody, M37, that recognizes a surface antigen on the first larval stage of the free-living nematode Caenorhabditis elegans. We demonstrate that wild-type C. elegans can be induced to display the M37 antigen on a later larval stage by altering the growth conditions. Mutations that result in nonconditional display of this antigen on all four larval stages fall into two classes. One class defines the new gene srf-6 II. The other mutations are in previously identified dauer-constitutive genes involved in transducing environmental signals that modulate formation of the dauer larva, a developmentally arrested dispersal stage. Although surface antigen switching is affected by some of the genes that control dauer formation, these two process can be blocked separately by specific mutations or induced separately by environmental factors. Based on these results, the mechanisms of nematode surface antigen switching can now be investigated directly.
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Affiliation(s)
- D G Grenache
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, MA 01609, USA
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109
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110
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Bidochka MJ, Hajek AE. Protoplast plasma membrane glycoproteins in two species of entomophthoralean fungi. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s0953-7562(96)80219-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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111
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Gems D, Maizels RM. An abundantly expressed mucin-like protein from Toxocara canis infective larvae: the precursor of the larval surface coat glycoproteins. Proc Natl Acad Sci U S A 1996; 93:1665-70. [PMID: 8643687 PMCID: PMC39999 DOI: 10.1073/pnas.93.4.1665] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Evasion of host immunity by Toxocara canis infective larvae is mediated by the nematode surface coat, which is shed in response to binding by host antibody molecules or effector cells. The major constituent of the coat is the TES-120 glycoprotein series. We have isolated a 730-bp cDNA from the gene encoding the apoprotein precursor of TES-120. The mRNA is absent from T. canis adults but hyperabundant in larvae, making up approximately 10% of total mRNA, and is trans-spliced with the nematode 5' leader sequence SL1. It encodes a 15.8-kDa protein (after signal peptide removal) containing a typical mucin domain: 86 amino acid residues, 72.1% of which are Ser or Thr, organized into an array of heptameric repeats, interspersed with proline residues. At the C-terminal end of the putative protein are two 36-amino acid repeats containing six Cys residues, in a motif that can also be identified in several genes in Caenorhabditis elegans. Although TES-120 displays size and charge heterogeneity, there is a single copy gene and a homogeneous size of mRNA. The association of overexpression of some membrane-associated mucins with immunosuppression and tumor metastasis suggests a possible model for the role of the surface coat in immune evasion by parasitic nematodes.
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Affiliation(s)
- D Gems
- Wellcome Research Centre for Parasitic Infections, Imperial College of Science, Technology and Medicine, London, United Kingdom
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112
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Martinez AM, De Souza W. A quick-frozen, freeze-fracture and deep-etched study of the cuticle of adult forms of Strongyloides venezuelensis (Nematoda). Parasitology 1995; 111 ( Pt 4):523-9. [PMID: 11023416 DOI: 10.1017/s0031182000066038] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The cuticle of adult forms of Strongyloides venezuelensis was studied by routine transmission electron microscopy, conventional freeze-fracture and also using quick-freeze and deep-etch techniques. In routine thin sections the cuticle of S. venezuelensis comprises 7 layers: epicuticle, outer cortical, inner cortical, external medial, internal medial, fibrous and basal. Observation of replicas of specimens fractured across the thickness of the body wall, revealed at the epicuticle an ordered array of particles accompanying the cuticular annulations. At the level of the cortical and medial layers we observed few scattered particles embedded in an amorphous matrix without a particular arrangement. The fibrous layer was represented by several parallel lines of ordered particles of similar size. In tangentially fractured specimens, the epicuticle cleaves readily exposing 2 faces, one exhibiting intramembranous particles without any particular arrangement, immersed in a smooth matrix (P face), and the other showing depressions and very few particles (E face). In replicas of fractures submitted to etching, we observed at the level of the cortical, medial fibrous and basal layers an interconnecting fibrous and globous structure which was organized in a different direction at the fibrous layer. The association of freeze-fracture to deep-etch technique revealed the internal structural organization of the cuticle layers showing details that were not seen before using conventional freeze-fracture technique.
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Affiliation(s)
- A M Martinez
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brasil
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113
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Abstract
At ultrastructural level, the Caenorhabditis elegans (C. elegans) cuticle shows the presence of well-defined layers, one of them is a membrane-like structure designated as epicuticle, always present on the outermost surface of nematodes. Freeze-fracture replicas revealed the existance of two faces of the epicuticle: a inner face containing numerous particles, and a almost smooth outer face. Deep etching replicas confirmed the existance of these two faces of the epicuticle showing in some replicas two particle populations on the outer face of L4 and adult forms of C. elegans. Also a previously unrecognized structure was noted in the cuticle of C. elegans, a matrix composed by network of globular and filamentous structures, leaving in between them spaces, which probably are occupied by water in the living adult and L4 larvae specimen. This network demonstrates either a compact nature or loose nature according to their cuticle location. Deep etching replicas of the adults nematode revealed large spaces between the cortical and basal layers which are regularly interrupted by struts connecting each other by fibers in a particular arrangement.
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Affiliation(s)
- C A Peixoto
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofí Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil
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114
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Riga E, Perry RN, Barrett J, Johnston MR. Biochemical analyses on single amphidial glands, excretory-secretory gland cells, pharyngeal glands and their secretions from the avian nematode Syngamus trachea. Int J Parasitol 1995; 25:1151-8. [PMID: 8557460 DOI: 10.1016/0020-7519(95)00046-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The gape nematode, Syngamus trachea, has been used as a model to study nematode secretions. Individual and intact pairs of amphidial glands, pharyngeal glands and pairs of excretory-secretory gland cells have been dissected and their secretory products analysed. The protein profiles of each gland and the total nematode secretions were analysed on 12.5% homogeneous SDS-PAGE minigels. The protein analyses revealed that the structural protein profile of each gland is different. The amphidial gland secretes two major proteins of 36.0 and 41.5 kDa, the excretory-secretory gland cell secretes a protein of 28.2 kDa and a protein of 14.3 kDa, and the pharyngeal gland secretes proteins of 41.5 and 14.6 kDa. Analysis of the total nematode secretions revealed all of the above major secretory proteins and an additional protein of 49.3 kDa. Syngamus trachea secretes acetylcholinesterases and its secretions contain multiple proteases.
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Affiliation(s)
- E Riga
- Entomology and Nematology Department, IACR, Rothamsted Experimental Station, Harpenden, U.K
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115
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Gems D, Ferguson CJ, Robertson BD, Nieves R, Page AP, Blaxter ML, Maizels RM. An abundant, trans-spliced mRNA from Toxocara canis infective larvae encodes a 26-kDa protein with homology to phosphatidylethanolamine-binding proteins. J Biol Chem 1995; 270:18517-22. [PMID: 7629180 DOI: 10.1074/jbc.270.31.18517] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A full-length mRNA encoding a secreted 26-kDa antigen of infective larvae of the ascarid nematode parasite Toxocara canis has been identified. This was characterized as a 1,082-base pair clone highly abundant (0.8-1.9%) in cDNA prepared from infective stage larvae but absent from cDNA from adult male worms. Sequence analysis revealed an open reading frame corresponding to a hydrophilic 263-amino acid residue polypeptide with a 20-residue N-terminal signal peptide, indicating that it is secreted. The 5' end of the cDNA was isolated by polymerase chain reaction using a primer containing the nematode-spliced leader sequence, SL1, showing that the mRNA is trans-spliced. The molecular mass of the putative protein with the signal peptide removed is 26.01 kDa, and antibody to the recombinant protein expressed in bacterial vectors reacts with a similarly sized protein in T. canis excretory/secretory (TES) products. An identical sequence was obtained from a genomic clone isolated by expression screening with mouse antibody to TES. The 72 amino acid residues adjacent to the signal peptide form two homologous 36-residue motifs containing 6 cysteine residues; this motif is found also in the T. canis-secreted glycoprotein TES-120 and in genes of Caenorhabditis elegans. Sequence data base searches revealed significant similarity to 7 other sequences in a newly recognized gene family of phosphatidylethanolamine-binding proteins that includes yeast, Drosophila, rat, bovine, simian, and human genes and a representative from the filarial nematode Onchocerca volvulus. Assays with the T. canis recombinant 26-kDa protein expressed as a fusion with maltose-binding protein have confirmed phosphatidylethanolamine-binding specificity for this novel product.
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Affiliation(s)
- D Gems
- Wellcome Research Centre for Parasitic Infections, Department of Biology, Imperial College of Science, Technology and Medicine, London, United Kingdom
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116
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Gilleard JS, Duncan JL, Tait A. An immunodominant antigen on the Dictyocaulus viviparus L3 sheath surface coat and a related molecule in other strongylid nematodes. Parasitology 1995; 111 ( Pt 2):193-200. [PMID: 7675534 DOI: 10.1017/s0031182000064945] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Monoclonal antibody 2A6 binds to the surface of the Dictyocaulus viviparus L3 sheath and identifies a molecule which is highly antigenic in both infected and vaccinated cattle. Immunogold electron microscopy reveals that the antibody binds to a highly stable surface coat overlying the epicuticle of the L3 sheath. The binding to the cuticular surface is stage specific, being restricted to the surface of the L3 sheath, although the antigen can be detected on Western blots of parasite homogenates from the L1 stage. Immunofluorescence on live parasites demonstrates that the antibodies also bind to the L3 sheath surface of many other strongylid nematodes. The antigen detected by 2A6 differs in molecular weight between the species; in D. viviparus the antigen is poorly resolved between 29 and 40 kDa by SDS-PAGE whereas in nematodes from the family Trichostrongyloidea a single band or doublet of approximately 20 kDa is detected, suggesting that a related molecule is present in these species. Although infection and vaccination with D. viviparus elicits a strong immune response to the L3 sheath antigen this does not appear to be the case following infection with other strongylid nematodes.
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Affiliation(s)
- J S Gilleard
- Department of Veterinary Parasitology, University of Glasgow
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117
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Dennis RD, Baumeister S, Smuda C, Lochnit C, Waider T, Geyer E. Initiation of chemical studies on the immunoreactive glycolipids of adult Ascaris suum. Parasitology 1995; 110 ( Pt 5):611-23. [PMID: 7596644 DOI: 10.1017/s0031182000065331] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
There is a general lack of basic information concerning one class of glycoconjugate, the glycolipids, from parasitic nematodes. As the prototype, the neutral glycolipid fraction derived from adult males of Ascaris suum was investigated as to its chromatographic, differential chemical staining, antigenic and chemical properties. The thin-layer chromatography-resolved neutral fraction glycolipids could be classified into components of fast and slow migrating band groups. Immunoreactivity was restricted to the latter as detected by IgG and IgM anti-neutral fraction glycolipid antibody levels in serial infection sera of mice. Similarities of chromatography, antigenicity and serological cross-reactivity have been extended to the neutral glycolipid fractions of other parasitic nematodes: Litomosoides carinii and Nippostrongylus brasiliensis. Chemical, differential chemical staining and enzymatic analyses identified the Ascaris suum antigenic, slow migrating band group of components as amphoteric glycosphingolipids, and not the originally hypothesized glycoglycerolipids or glycosylphosphatidylinositols, that contained typical neutral monosaccharide constituents and a zwitterionic phosphodiester linkage, most probably phosphocholine. Glycosphingolipid-immunoreactivity is eliminated on cleavage of the zwitterionic phosphodiester linkage by hydrofluoric acid treatment.
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Affiliation(s)
- R D Dennis
- Allgemeine und Medizinische Parasitologie, FB Biologie, Philipps-Universität Marburg, Germany
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118
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Modha J, Kusel JR, Kennedy MW. A role for second messengers in the control of activation-associated modification of the surface of Trichinella spiralis infective larvae. Mol Biochem Parasitol 1995; 72:141-8. [PMID: 8538685 DOI: 10.1016/0166-6851(95)00080-k] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The involvement of second messengers in the control of activation-induced changes to the surface of Trichinella spiralis infective larvae was investigated using membrane-permeant photo-activatable 'caged' compounds to alter intracellular levels of inositol trisphosphate (IP3), calcium ions (Ca2+) and cyclic AMP (cAMP). Activation of larvae by incubation in culture medium containing trypsin and bile was followed by the loss of the surface coat labelled with the fluorescent PKH26 lipid probe and this correlated with the reciprocal acquisition of surface lipophilicity detected using the fluorescent lipid probe octadecanoyl aminofluorescein (AF18). Optimal surface coat shedding and AF18 insertion was also achieved following photolysis of caged mediators liberating IP3, Ca2+ or cAMP within the parasite. Chelation of Ca2+, however, abolished the effects of larval activation. Nevertheless, addition of cAMP (but not IP3) to Ca(2+)-depleted larvae overcame this inhibition and restored AF18 insertion to levels achieved by activated parasites. Therefore, the existence of a linear second messenger pathway involving the sequential release of IP3, Ca2+ and then cAMP is likely.
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Affiliation(s)
- J Modha
- Department of Biochemistry, University of Glasgow, UK
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119
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Ashman K, Mather J, Wiltshire C, Jacobs HJ, Meeusen E. Isolation of a larval surface glycoprotein from Haemonchus contortus and its possible role in evading host immunity. Mol Biochem Parasitol 1995; 70:175-9. [PMID: 7637698 DOI: 10.1016/0166-6851(94)00210-e] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- K Ashman
- Centre for Animal Biotechnology, School of Veterinary Science, University of Melbourne, Parkville, Australia
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120
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Plenge-Bönig A, Krömer M, Büttner DW. Light and electron microscopy studies on Onchocerca jakutensis and O. flexuosa of red deer show different host-parasite interactions. Parasitol Res 1995; 81:66-73. [PMID: 7724516 DOI: 10.1007/bf00932419] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Adult filariae of two intranodular Onchocerca species of red deer (Cervus elaphus) were examined at the ultrastructural level. In all, 90 nodules of O. flexuosa and 20 nodules of O. jakutensis were studied by histology. O. jakutensis caused cystic and pus-filled nodules in which the female and male worms were motile. Female worms possessed a thick cuticle and a well-developed somatic musculature. The basal lamina of the muscular syncytia was connected with the transhypodermal fibers through long protrusions. The epicuticle had only few protuberances and no visible surface coat. Female O. flexuosa showed morphological features similar to those of other intranodular filariae. A surface coat could not be detected. In 24% of 33 nodules with young live female worms and 40% of 38 nodules with older live female O. flexuosa the worms were surrounded by giant cells apparently attacking a cuticle. This was found even in nodules obtained from animals no older than 9 months. It is probable that the lack of a surface coat protecting the female worm and the inability to move due to the reduced somatic muscles lead to an early elimination of O. flexuosa by the host's immune system.
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Affiliation(s)
- A Plenge-Bönig
- Bernhard-Nocht-Institut für Tropenmedizin, Abteilung Helminthologie, Hamburg, Germany
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121
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Modha J, Robertson WM, Kennedy MW, Kusel JR. Characterization of a major surface-associated excretory-secretory antigen of Trichinella spiralis larvae with antibodies to keyhole limpet haemocyanin. Parasitology 1994; 109 ( Pt 4):531-8. [PMID: 7800420 DOI: 10.1017/s0031182000080793] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A multi-subunit antigen (native M(r) > 200 kDa, reduced M(r) 97-100 kDa) has been identified in homogenates of Trichinella spiralis larvae using affinity-purified rabbit anti-keyhole limpet haemocyanin (KLH) antibodies and its cross-reactivity with KLH was confirmed by competition blotting. The antigen was not present at the larval surface but was exposed after treatment of the larvae with the detergent cetyltrimethyl ammonium bromide (CTAB) which removed the surface coat. This correlated with a significant decrease in insertion of the surface-restricted fluorescent lipid probe AF18, indicating that the surface coat must be lipidic in nature. Unlike KLH, the larval antigen blotted onto nitrocellulose was itself periodate insensitive. Periodate treatment of whole larvae, however, resulted in shedding of the surface, to which anti-KLH antibodies then bound intensely. Anti-KLH antibodies also recognized three (49, 55, 108 kDa) of the four most dominant antigens in excretory-secretory (ES) products of cultured larvae, whose excretion-secretion was increased with CTAB. The nature, location and function of the antigen is discussed.
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Affiliation(s)
- J Modha
- Department of Biochemistry, University of Glasgow
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122
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Araujo A, Souto-Padrón T, De Souza W. An ultrastructural, cytochemical and freeze-fracture study of the surface structures of Brugia malayi microfilariae. Int J Parasitol 1994; 24:899-907. [PMID: 7982752 DOI: 10.1016/0020-7519(94)90016-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Ultrastructural analysis of the cuticle of Brugia malayi microfilariae indicated that it is composed of 2 regions: the inner one 15-20 nm thick with a homogeneous aspect and the outer one, designated as epicuticle, which is 15-20 nm thick. Three laminae separated by electron-lucent regions were seen in the epicuticle. Labeling of the cuticle and epicuticle of B. malayi and Wuchereria bancrofti microfilariae was observed when thin sections of Lowicryl-embedded parasites were incubated in the presence of gold-labeled phospholipase-C. Replicas of freeze-fractured microfilariae showed the presence of 2 fracture planes in the epicuticle and no fracture plane in the inner region of the cuticle. The P face of the epicuticle outer fracture plane presented few particles similar to intramembranous particles (IMPs). The epicuticle inner fracture plane P and E faces presented large numbers of densely-packed small particles and many protuberances. Also, fracture faces of hypodermal and muscle cell plasma membranes were analyzed. Faces P and E of fractured membranes showed the presence of typical IMPs. P faces of both membranes showed larger amounts of particles than E faces. Fracture of muscle plasma membrane revealed a linear array of particles disposed in parallel rows on its P face.
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Affiliation(s)
- A Araujo
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil
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Weber N, Vosmann K, Aitzetmüller K, Filipponi C, Taraschewski H. Sterol and fatty acid composition of neutral lipids of Paratenuisentis ambiguus and its host eel. Lipids 1994; 29:421-7. [PMID: 8090063 DOI: 10.1007/bf02537311] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The sterol composition of free sterol and steryl ester fractions of the fish parasite Paratenuisentis ambiguus was determined. In addition, the fatty acid composition of various neutral lipid classes, i.e., wax esters, steryl esters, triacylglycerols and free fatty acids, as well as the composition of the 1-O-alkyl moieties of total ether glycerolipids of the parasite, were investigated. The results of these studies were compared with those obtained on the intestinal tract tissue of its host, the eel (Anguilla anguilla). Cholesterol is the major sterol in both P. ambiguus and A. anguilla. However, the sterols of P. ambiguus contain high proportions (> 20%) of other sterols, such as campesterol and various dehydrosterols. [e.g., 7-dehydrocholesterol and cholesta-5,22(E)-dienol]. The presence of these minor sterols agrees with the known biotransformations of exogenous sterols in various helminths. Considerable differences are found in the fatty acid composition of neutral lipid fractions, as well as the total lipid extract from the endoparasite as compared to the host tissue. In particular, eicosapentaenoic acid (20:5n-3), other polyunsaturated fatty acids, such as 20:4n-6, 22:5n-3 and 22:6n-3, as well as long-chain saturated fatty acids, such as 20:0, are generally enriched in the neutral lipid fractions of the parasite as compared to those of infected eel intestine.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- N Weber
- Institut für Biochemie und Technologie der Fette, BAGKF, Münster, Germany
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Lee DL, Wright KA, Shivers RR. A freeze-fracture study of the cuticle of adult Nippostrongylus brasiliensis (Nematoda). Parasitology 1993; 107 ( Pt 5):545-52. [PMID: 8295793 DOI: 10.1017/s0031182000068128] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The surface of the cuticle of adult Nippostrongylus brasiliensis has been studied by means of the freeze-fracture technique and by transmission electron microscopy. Some of the surface coat appears to have been shed from the surface of the cuticle of adults fixed in situ in the intestine of its host and from the surface of individuals removed from the intestine and freeze-fractured. Freeze-fracturing the cuticle of individuals removed from the host has shown that this surface coat varies in thickness from 30 to 90 nm. The epicuticle is about 20 nm thick and cleaves readily to expose E- and P-faces. The P-face of the epicuticle possesses a small number of particles, similar to intra-membranous particles, whilst the E-face possesses a few, widely scattered depressions. Despite the presence of these particles the epicuticle is not considered to be a true membrane. Freeze-fracturing the remainder of the cuticle has confirmed its structure as described by conventional transmission electron microscopy. Clusters of particles on the P-face of the outer epidermal (hypodermal) membrane and corresponding depressions on the E-face of the membrane are though to be associated with points of attachment of the cuticle to the epidermis (hypodermis). No differences in appearance of the cuticle and its surface layers were observed in individuals taken from 7-, 10-, 13- and 15-day infections.
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Affiliation(s)
- D L Lee
- Department of Pure and Applied Biology, University of Leeds, U.K
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125
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Maizels RM, Bundy DA, Selkirk ME, Smith DF, Anderson RM. Immunological modulation and evasion by helminth parasites in human populations. Nature 1993; 365:797-805. [PMID: 8413664 DOI: 10.1038/365797a0] [Citation(s) in RCA: 402] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Helminth parasites are highly prevalent in human communities in developing countries. In an endemic area an infected individual may harbour parasitic worms for most of his or her life, and the ability of these infections to survive immunological attack has long been a puzzle. But new techniques are starting to expose the diverse mechanisms by which these agents modulate or evade their hosts' defences, creating a dynamic interaction between the human immune system and the parasite population.
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Affiliation(s)
- R M Maizels
- Wellcome Research Centre for Parasitic Infections, Department of Biology, Imperial College of Science, Technology and Medicine, London, UK
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126
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Pendland JC, Hung SY, Boucias DG. Evasion of host defense by in vivo-produced protoplast-like cells of the insect mycopathogen Beauveria bassiana. J Bacteriol 1993; 175:5962-9. [PMID: 8376342 PMCID: PMC206677 DOI: 10.1128/jb.175.18.5962-5969.1993] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
In vivo cells (hyphal bodies) of the hyphomycetous insect pathogen Beauveria bassiana collected from host Spodoptera exigua larval hemolymph were osmotically sensitive and lacked a well-defined cell wall. In light and electron microscope studies, a galactose-specific lectin purified from S. exigua hemolymph, concanavalin A (specific for alpha-mannose), and a polyclonal antibody to B. bassiana cell walls all bound to surfaces of in vitro-produced B. bassiana blastospores; however, none of these probes labelled the thin layer of extracellular material covering the plasma membranes of hyphal bodies. These cells were observed freely circulating in S. exigua hemolymph at 36 h postinfection, although immunocompetent hemocytes were known to be present. Additionally, association of hyphal bodies with hemocytes in monolayers was significantly less than for opsonized in vitro blastospores or submerged conidia. The absence of antigenically important galactomannan components on in vivo cells may therefore allow these cells to escape recognition and phagocytosis. Lack of structural components (e.g., chitin, as evidenced by the absence of binding of wheat germ agglutinin) may also be important with respect to evasion of host cellular defense mechanisms. Production of wall material resumed 48 to 60 h postinfection and therefore may coincide with loss of phagocytic capabilities of the hemocytes due to immunosuppressive effects of fungal metabolites. The protoplast-like cells may be formed by the action of hydrolytic enzymes in the hemocytes or by inhibition of fungal cell wall synthetases.
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Affiliation(s)
- J C Pendland
- Department of Entomology and Nematology, University of Florida, Gainesville 32611-0620
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