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Infection and Immunity Jan 2008Chitinases of pathogens have been proposed as potential targets of vaccines or specific inhibitors. We studied the genomic organization, transcript levels, developmental...
Chitinases of pathogens have been proposed as potential targets of vaccines or specific inhibitors. We studied the genomic organization, transcript levels, developmental expression, and biological function of chitinases in the rodent filarial nematode Acanthocheilonema viteae, a model organism for human-pathogenic filarial worms. Characterization of nine genomic clones from an A. viteae phage library and Southern blot experiments revealed the existence of three different chitinase genes, two of which could theoretically yield functional transcripts. The deduced proteins of these genes had the common modular organization of family 18 chitinases. Northern blot experiments and rapid amplification of cDNA ends-PCR with adult worms and larval stages showed that only one gene is expressed, with high variation in transcript levels, as determined by real-time PCR. Chitinase transcript levels were lowest in the late male stage 4 larva (L4) and peaked in the stage 3 larva (L3), which was corroborated by Western blotting. RNA interference (RNAi) experiments showed that treatment of L3 and adult female worms with double-stranded RNA of chitinase inhibited molting of L3 worms and hatching of microfilariae. RNAi also led to the death of 50% of female worms, revealing the essential role of chitinase in the life cycle of filarial nematodes.
Topics: Animals; Chitinases; Dipetalonema; Female; Gene Expression Regulation; Genes, Helminth; Genome, Helminth; Helminth Proteins; Life Cycle Stages; Male; Molecular Sequence Data; RNA Interference
PubMed: 17938220
DOI: 10.1128/IAI.00701-07 -
The Journal of Parasitology Jun 2007We describe a new species of Dipetalonema occurring in the body cavity of Ateles chamek (Humboldt, 1812) from north-central Bolivia. Morphologic characters serving to...
We describe a new species of Dipetalonema occurring in the body cavity of Ateles chamek (Humboldt, 1812) from north-central Bolivia. Morphologic characters serving to separate Dipetalonema yatesi n. sp. from known forms include a vagina vera with a simple tube and thin walls and a left spicule, which possesses a handle shorter than the lamina (ratio 2.7); the latter displays an anterior membranous alae similar in length to the terminal flagellum, a distal extremity of the left spicule within a simple hook and a membrane, phasmids at the basis of the lappets, and heterogeneous muscles occupying the whole cavity. Dipetalonema yatesi n. sp. can be separated from Dipetalonema robini, Dipetalonema gracile, and Dipetalonema graciliformis, between other characters, in having a simple vagina vera instead of a sinuous one, and from Dipetalonema caudispina and Dipetalonema freitasi in having the lamina of the left spicule divided in a membranous alae and a terminal flagellum.
Topics: Animals; Atelinae; Bolivia; Dipetalonema; Dipetalonema Infections; Female; Male; Microscopy, Electron, Scanning; Monkey Diseases
PubMed: 17626361
DOI: 10.1645/GE-962R1.1 -
Microbiology (Reading, England) Dec 2005Current phylogenies of the intracellular bacteria belonging to the genus Wolbachia identify six major clades (A-F), termed 'supergroups', but the branching order of...
Phylogeny of Wolbachia pipientis based on gltA, groEL and ftsZ gene sequences: clustering of arthropod and nematode symbionts in the F supergroup, and evidence for further diversity in the Wolbachia tree.
Current phylogenies of the intracellular bacteria belonging to the genus Wolbachia identify six major clades (A-F), termed 'supergroups', but the branching order of these supergroups remains unresolved. Supergroups A, B and E include most of the wolbachiae found thus far in arthropods, while supergroups C and D include most of those found in filarial nematodes. Members of supergroup F have been found in arthropods (i.e. termites), and have previously been detected in the nematode Mansonella ozzardi, a causative agent of human filariasis. To resolve the phylogenetic positions of Wolbachia from Mansonella spp., and other novel strains from the flea Ctenocephalides felis and the filarial nematode Dipetalonema gracile, the authors generated new DNA sequences of the Wolbachia genes encoding citrate synthase (gltA), heat-shock protein 60 (groEL), and the cell division protein ftsZ. Phylogenetic analysis confirmed the designation of Wolbachia from Mansonella spp. as a member of the F supergroup. In addition, it was found that divergent lineages from Dip. gracile and Cte. felis lack any clear affiliation with known supergroups, indicating further genetic diversity within the Wolbachia genus. Finally, although the data generated did not permit clear resolution of the root of the global Wolbachia tree, the results suggest that the transfer of Wolbachia spp. from arthropods to nematodes (or vice versa) probably occurred more than once.
Topics: Animals; Bacterial Proteins; Chaperonin 60; Cytoskeletal Proteins; DNA, Bacterial; Filarioidea; Genes, Bacterial; Insecta; Phylogeny; RNA, Ribosomal, 16S; Symbiosis; Wolbachia
PubMed: 16339946
DOI: 10.1099/mic.0.28313-0 -
Parasite Immunology Jan 2003Filarial infections are characterized by high IgE antibody responses. So far, it is not clear whether IgE antibodies are involved in protection, pathology or both. We...
Filarial infections are characterized by high IgE antibody responses. So far, it is not clear whether IgE antibodies are involved in protection, pathology or both. We established a bioassay to detect reactive IgE antibodies in jirds infected with the filaria Acanthocheilonema viteae. Sera of A. viteae-infected jirds were used to sensitize rat basophil leukaemia (RBL) cells and degranulation was stimulated by addition of antigens of A. viteae. Reactive IgE responses were detected from 2 weeks post infection (p.i.) and throughout the A. viteae infection. Male antigen triggered the strongest mediator release, followed by female worms, infective larvae (L3) and microfilariae. Separation of male and female antigen indicated that several antigens of both genders are potent allergens. In particular, one male specific allergen of about 550 kDa induced strongest degranulation of RBL cells. In addition, mediator release stimulated by antigen fractions of about 15 kDa was due to filarial cystatin. In conclusion, we describe a convenient in vitro assay to examine IgE mediated responses in jirds. A sex specific filarial protein with high allergenic potential is identified and cystatin is established as a potent allergen of A. viteae.
Topics: Allergens; Animals; Antibodies, Helminth; Antigens, Helminth; Biological Assay; Cells, Cultured; Chromatography, High Pressure Liquid; Cystatins; Dipetalonema; Dipetalonema Infections; Female; Filariasis; Gerbillinae; Immunoglobulin E; Male; Rats
PubMed: 12753433
DOI: 10.1046/j.1365-3024.2003.00496.x -
Biophysical Journal Jan 2003ES-62, a protein secreted by filarial nematodes, parasites of vertebrates including humans, has an unusual posttranslational covalent addition of phosphorylcholine to an... (Comparative Study)
Comparative Study
ES-62, a protein secreted by filarial nematodes, parasites of vertebrates including humans, has an unusual posttranslational covalent addition of phosphorylcholine to an N-type glycan. Studies on ES-62 from the rodent parasite Acanthocheilonema viteae ascribe it a dominant role in ensuring parasite survival by modulating the host immune system. Understanding this immunomodulation at the molecular level awaits full elucidation but distinct components of ES-62 may participate: the protein contributes aminopeptidase-like activity whereas the phosphorylcholine is thought to act as a signal transducer. We have used biophysical and bioinformatics-based structure prediction methods to define a low-resolution model of ES-62. Sedimentation equilibrium showed that ES-62 is a tightly bound tetramer. The sedimentation coefficient is consistent with this oligomer and the overall molecular shape revealed by small angle x-ray scattering. A 19 A model for ES-62 was restored from the small-angle x-ray scattering data using the program DAMMIN which uses simulated annealing to find a configuration of densely packed scattering elements consistent with the experimental scattering curve. Analysis of the primary sequence with the position-specific iterated basic local alignment search tool, PSI-BLAST, identified six closely homologous proteins, five of which are peptidases, consistent with observed aminopeptidase activity in ES-62. Differences between the secondary structure content of ES-62 predicted using the consensus output from the secondary structure prediction server JPRED and measured using circular dichroism are discussed in relation to multimeric glycosylated proteins. This study represents the first attempt to understand the multifunctional properties of this important parasite-derived molecule by studying its structure.
Topics: Amino Acid Sequence; Animals; Circular Dichroism; Dipetalonema; Helminth Proteins; Models, Molecular; Molecular Sequence Data; Protein Conformation; Protein Structure, Quaternary; Protein Structure, Secondary; Protein Structure, Tertiary; Sequence Alignment; Sequence Analysis, Protein; Sequence Homology, Amino Acid; Solutions
PubMed: 12524301
DOI: 10.1016/S0006-3495(03)74868-1 -
Parasite Immunology May 2002Cystatins of two filarial nematodes were studied with regard to their capacity to up-regulate the production of nitric oxide (NO) in vitro, and the effects were...
Cystatins of two filarial nematodes were studied with regard to their capacity to up-regulate the production of nitric oxide (NO) in vitro, and the effects were analysed. Recombinant cystatin of the human pathogenic filaria Onchocerca volvulus and of the rodent filaria Acanthocheilonema viteae significantly enhanced the NO production of interferon (IFN)-gamma-activated macrophages of BALB/c and C3H/HeJ mice. Truncated cystatins lacking the N-terminal protease inhibitory active site, and showing marginal protease inhibitory activity, up-regulated the NO production to the same extent as the full-length proteins, indicating that the effect on the NO production is independent of cysteine protease inhibition. NO did not contribute to the suppression of proliferative T cell responses exerted by filarial cystatins, as shown in other studies, since NO synthase inhibitors did not restore proliferative responses. The up-regulation of NO production induced by filarial cystatins was partly dependent on the production of interleukin-10 and tumour necrosis factor-alpha, since depletion of both cytokines by antibodies led to a diminution of the enhanced NO production by 22-48%. Our data suggest that filarial cystatins are potent triggers of the production of NO, a mediator which was shown to have a role as an effector molecule against filarial worms in vitro and in vivo.
Topics: Adjuvants, Immunologic; Animals; Cystatins; Dipetalonema; Filariasis; Interferon-gamma; Interleukin-10; Life Cycle Stages; Macrophage Activation; Mice; Nitric Oxide; Onchocerca volvulus; Polysaccharides, Bacterial; T-Lymphocytes; Tumor Necrosis Factor-alpha; Up-Regulation
PubMed: 12060319
DOI: 10.1046/j.1365-3024.2002.00459.x -
Cadernos de Saude Publica 2001A survey on the prevalence of Dirofilaria immitis and Dipetalonema reconditum was conducted in 1,519 dogs from Maceió and two coastal areas in the State of Alagoas,...
A survey on the prevalence of Dirofilaria immitis and Dipetalonema reconditum was conducted in 1,519 dogs from Maceió and two coastal areas in the State of Alagoas, Northeast Brazil, from 1995 to 1999, by testing for microfilariae in blood. All blood samples were from exclusively domiciled dogs with a known history, showing that the infections were autochthonous, confirming transmission of canine filariasis in these areas. In Greater Metropolitan Maceió, 15 (1.3%) microfilaremic dogs were detected with D. immitis and 15 (1,3%) with D. reconditum. In the southern coastal area there was an estimated prevalence of 12.7% for D. immitis. D. immitis and D. reconditum microfilaria were 298.1 micrometer and 249.2 micrometer long and 7.3 micrometer and 4.4 micrometer wide, respectively. A Witness immunotest that detects D. immitis antigen was used to confirm parasitological results and reveal occult dirofilariasis cases. Of the total 6,579 females examined, 8 (0.1%) Culex quinquefasciatus were observed to be naturally infected with D. immitis larvae. These results proved dirofilariasis transmission in Maceió and demonstrated D. reconditum in the same geographic area.
Topics: Animals; Antigens, Helminth; Brazil; Dipetalonema; Dipetalonema Infections; Dirofilaria immitis; Dirofilariasis; Dog Diseases; Dogs; Female; Male; Prevalence
PubMed: 11784911
DOI: 10.1590/s0102-311x2001000600021 -
The British Journal of Ophthalmology Nov 2001
Topics: Anesthesia, Local; Animals; Dipetalonema; Dipetalonema Infections; Eye Infections, Parasitic; Filaricides; Humans; Male; Middle Aged; Treatment Outcome
PubMed: 11702740
DOI: 10.1136/bjo.85.11.1384i -
Parasite Immunology Dec 1999ES-62 is a phosphorylcholine (PC)-containing glycoprotein which is secreted by the rodent filarial nematode Acanthocheilonema viteae. A homologue exists in the human... (Review)
Review
ES-62 is a phosphorylcholine (PC)-containing glycoprotein which is secreted by the rodent filarial nematode Acanthocheilonema viteae. A homologue exists in the human filarial nematode Brugia malayi and indeed PC is found attached to glycoproteins of many, if not all, filarial species. At concentrations equivalent to those found for PC-containing molecules in the bloodstream of parasitized humans, ES-62 is able to polyclonally activate certain protein tyrosine kinase and mitogen-activating protein kinase signal-transduction elements in B and T lymphocytes following in-vitro exposure. Although this interaction is insufficient to cause lymphocyte proliferation per se, it serves to desensitize the cells to subsequent activation of the phosphoinositide-3-kinase, protein kinase C and Ras mitogen-activating protein kinase pathways and hence also to proliferation via the antigen receptors. The active component of ES-62 appears to be PC, as the results obtained with ES-62 are broadly mimicked by PC conjugated to BSA or PC alone. Although PC can also be shown to desensitize B cells following in-vivo administration, not all cells are affected, as it is still possible to generate an antibody response. Dissection of this response indicates that it is of the Th2 type.
Topics: Animals; Antibodies, Helminth; B-Lymphocytes; Dipetalonema; Glycoproteins; Helminth Proteins; Humans; Interleukin-4; Molecular Sequence Data; Phosphatidylinositol 3-Kinases; Phosphorylcholine; Protein Kinase C; Signal Transduction; T-Lymphocytes; ras Proteins
PubMed: 10583862
DOI: 10.1046/j.1365-3024.1999.00267.x -
Infection and Immunity Dec 1999Ov20 is a structurally novel 20-kDa retinol binding protein secreted by Onchocerca volvulus. Immunological and biological investigation of this protein has been hampered... (Comparative Study)
Comparative Study
Ov20 is a structurally novel 20-kDa retinol binding protein secreted by Onchocerca volvulus. Immunological and biological investigation of this protein has been hampered by the inability to maintain O. volvulus in a laboratory setting. In an effort to find a system more amenable to laboratory investigation, we have cloned, sequenced, and expressed cDNA encoding homologues of Ov20 from two closely related filarial species, Brugia malayi (Bm20) and Acanthocheilonema viteae (Av20). Sequence comparisons have highlighted differences in glycosylation of the homologues. We present here an analysis of mouse immune responses to Ov20, Bm20, and Av20. The results suggest a strong genetic restriction in response to native Bm20 that is overcome when recombinant, nonnative material is used. Reactivity of human filarial sera to the three recombinant proteins confirmed previous specificity studies with Ov20 but highlighted important differences in the reactivity patterns of the O. volvulus and B. malayi homologues that may be due to differences in glycosylation patterns. Ov20 is a dominant antigen in infected individuals, while Bm20 is not. The availability of the B. malayi homologue enabled us to use defined murine reagents and inbred strains for genetic analysis of responsiveness in a way that is not possible for Ov20. However, the close sequence similarity between Ov20 and Av20 suggests that the A. viteae model may be more suited to the investigation of the biological functions of Ov20.
Topics: Amino Acid Sequence; Animals; Antibodies, Helminth; Antigens, Helminth; Brugia malayi; Cloning, Molecular; Dipetalonema; Filariasis; Glycosylation; Helminth Proteins; Humans; Immunization; Mice; Mice, Inbred Strains; Molecular Sequence Data; Onchocerca volvulus; Onchocerciasis; Recombinant Proteins; Retinol-Binding Proteins; Sequence Homology, Amino Acid; Wuchereria bancrofti
PubMed: 10569745
DOI: 10.1128/IAI.67.12.6329-6334.1999