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Query: UMLS:C0042961 (volvulus)
 4,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Infestation with organisms causing lymphatic filariasis (i.e. Wuchereria bancrofti and Brugia malayi) results in a variety of clinical presentations. It is possible that some of the variation is due to differences in host response to parasite. To determine whether individuals who live in an endemic area but differ in their clinical manifestations respond to different filarial antigens, we screened Onchocerca volvulus expression libraries with sera from a number of individuals belonging to different clinical groups. The results of the study demonstrate that there are indeed differences in the recognition of three cloned filarial antigens and that this differential recognition is related to clinical symptomatology. The most striking finding is that an Onchocerca volvulus protein homologous to the 70 kDa Xenopus laevis heat shock protein is primarily recognized by individuals who are amicrofilaremic. Further analysis is required to determine whether these antigens play any role in the pathogenesis of filarial infection or have any potential value in protective immunity.
Mol Biochem Parasitol 1989 Mar 15
PMID:Onchocerca volvulus heat shock protein 70 is a major immunogen in amicrofilaremic individuals from a filariasis-endemic area. 270 88

Surface radioiodination of adult Onchocerca parasites reveals a restricted range of proteins associated with the cuticle. We present data to show that prominent among these is a complex of low-molecular-weight proteins which can be released in soluble form by homogenisation of surface-labelled Onchocerca gutturosa in phosphate-buffered saline (PBS). One of this groups of proteins, designated gp20, has a molecular mass of 20,000, is glycosylated with two N-linked carbohydrate side chains, and has a basic pI. Other PBS-soluble, 125I-labelled proteins of similar size appear not to be glycosylated. A distinct group of molecules are released only in the presence of reducing agents, and are likely to be cuticular collagens. The low-molecular-weight components are antigenic and cross-reactive with Onchocerca volvulus infection sera. Cross-reactions are also observed in immunoprecipitation experiments using sera from Brugia-immunised animals and infected humans. Comparative two-dimensional analyses of these immunoprecipitates reveal at least two Onchocerca specific components. As an alternative to radiolabelling and PBS homogenisation, incubation of worms in medium containing the reducing agent 2-mercaptoethanol resulted in a similar set of molecules being released into the medium. Since surface antigens of O. gutturosa from bovines and O. volvulus from humans appear similar in size and are antigenically cross-reactive, the more readily available parasite is being used to study further the properties of these molecules and to provide reagents for raising antisera reactive to the equivalent O. volvulus antigens.
Mol Biochem Parasitol 1989 May 15
PMID:Biochemical and immunochemical characterisation of a 20-kilodalton complex of surface-associated antigens from adult Onchocerca gutturosa filarial nematodes. 273 28

Nematode spermatozoa, unlike their mammalian counterparts, are nonflagellated crawling cells. The pseudopod of these cells contains the major sperm protein (MSP) which comprises more than 15% of the protein in the sperm. MSP is presumed to function as a cytoskeletal element involved in motility. An Ascaris MSP cDNA sequence was used as a probe to identify and isolate Onchocerca volvulus MSP clones from a lambda gt11 genomic library. Two clones, OVGS-1 (765 bp) and OVGS-2 (1765 bp), were characterized by restriction endonuclease mapping and sequence analysis. Both genomic clones contain MSP protein coding regions of 99 and 282 bp separated by an intervening sequence of 153 bp. The genes OVGS-1 and OVGS-2 are 95% similar in nucleotide sequence in the protein coding regions, but only 79% similar in their intron sequences. A number of potential regulatory sequences in the flanking regions and at the exon/intron junctions of the O. volvulus MSP genes are in good agreement with consensus sequences in other eukaryotic cells. The nucleotide sequence of the O. volvulus MSP genes were over 80% similar to the Ascaris MSP cDNA sequence and 79% similar to the Caenorhabditis MSP-3 cDNA. The predicted amino acid sequence of the O. volvulus MSPs were 96% similar to each other, 90-91% similar to Ascaris MSP and 81-82% similar to Caenorhabditis MSP-3. These results offer evidence that the MSP sequences have been highly conserved throughout nematode evolution but are variable in their genomic organization and the presence of introns.
Mol Biochem Parasitol 1989 Sep
PMID:Major sperm protein genes from Onchocerca volvulus. 277 Jul 87

A cloned sequence, pOvs134, was isolated from a genomic library prepared from Onchocerca volvulus of savanna origin in the plasmid pUC9. pOvs134 hybridizes to all the geographic isolates of O. volvulus tested from both the New and the Old World, but not to the species Onchocerca gibsoni, Onchocerca gutturosa, Onchocerca ochengi, Onchocerca cervicalis, the filarial parasites Brugia malayi, or Dirofilaria immitis, nor to human or simuliid DNA. As little as 250 pg of DNA can be detected on a dot blot hybridization, suggesting that pOvs134 is sensitive enough to detect a single third stage larva. DNA sequence analysis of the inserted DNA of pOvs134 revealed that it consisted of twelve examples of a 149-bp repeat. The sequence of this repeat is strikingly similar to that of two O. volvulus genomic clones previously described, one of which has been reported to be specific for forest form O. volvulus, and one of which hybridizes to genomic DNA of several species of Onchocerca. These results suggest that the 149-bp repeat sequence is highly repeated in the genome of O. volvulus, and that variants of this repeat with different specificities exist.
Mol Biochem Parasitol 1989 Aug
PMID:Cloning and characterization of an Onchocerca volvulus specific DNA sequence. 281 41

Dolichol kinase was demonstrated in the microsomal fraction of Ascaris suum and Onchocerca volvulus. The enzyme from nematodes exhibited specificity for CTP as phosphoryl donor and was found to be inhibited by the reaction product CDP. Enzyme activity was optimal at pH 7.4, in the temperature range between 30 degrees and 37 degrees C, and in the presence of 0.5% Triton X-100. In addition, the enzyme was found to depend on divalent cations for activity; Mg2+ being more effective than Mn2+ and Ca2+. The dolichol kinase from both nematodes was shown to be independent of Ca2+-calmodulin for activity. The apparent Km values for dolichol were determined to be 7.5 and 9.0 micrograms ml-1 for the enzyme from A. suum and O. volvulus, respectively. Those for CTP were estimated to be 0.85 and 0.75 mM, respectively.
Mol Biochem Parasitol 1985 Feb
PMID:Dolichol kinase in Ascaris suum and Onchocerca volvulus. 298 82

The presence of 5'-nucleotidase was demonstrated in Onchocerca volvulus and Dirofilaria immitis; the bulk of activity was found in the particulate fraction. The enzyme of filarial worms exhibited a broad pH-optimum between 6.4 and 8.0 and substrate specificity for nucleotides compared to glucose-6-phosphate and p-nitrophenyl phosphate. The apparent Km-values for AMP were found to be 0.15 mM and 0.22 mM for the enzyme from O. volvulus and D. immitis, respectively. The activity of 5'-nucleotidase from both filarial worms was effectively inhibited by the filaricidal compound CGP 8065, a dithiocarbamate-derivative of amoscanate, whereas the 5'-nucleotidase from rat liver was not affected. The parasite-specific inhibition by CGP 8065 was found to be reversible and to be competitive with respect to the substrate AMP. The inhibition constants were calculated to be 24 microM and 8 microM for the enzyme from O. volvulus and D. immitis, respectively.
Mol Biochem Parasitol 1985 Aug
PMID:Parasite-specific inhibition of 5'-nucleotidase from Onchocerca volvulus and Dirofilaria immitis by the amoscanate-derivative CGP 8065. 299 82

Two repeated sequences, plasmids pOV8 and pOV26, were cloned and characterized from the filarial parasite Onchocerca volvulus. Both clones can be used to distinguish O. volvulus DNA from other Onchocerca species or other nematodes by restriction fragment length polymorphisms, but neither clone can differentiate between DNA from savanna (Mali) or forest (Ivory Coast) O. volvulus isolates. DNA from one O. volvulus infective larva can be detected by both clones in dot blot hybridization assays. Neither clone cross hybridizes with DNA from host or vector species (human or simuliid, respectively). pOV26 is a member of an interspersed repeated DNA family composed of at least 100 members, and is only observed in the genus Onchocerca. Repeated DNA clone pOV8 cross reacts with DNA from other parasitic filarial nematodes, and is also present in at least 100 copies per O. volvulus genome. pOV26 is a potential tool in the diagnosis of human onchocerciasis, since it is specific for the genus Onchocerca. In the future, we plan to look for regions of these repeated sequences which may serve as a basis for the development of probes to discriminate among Onchocerca species and strains using a simple dot hybridization test.
Mol Biochem Parasitol 1986 Nov
PMID:Cloning and characterization of two Onchocerca volvulus repeated DNA sequences. 302 1

The existence of the nuclear enzyme ADP-ribosyl transferase in the filarial worm Onchocerca volvulus was demonstrated. The enzyme activity was observed in the nuclear preparation from the parasitic organism. Poly(ADP-ribose) was identified as the reaction product by the isolation of phosphoribosyl-AMP and 5'AMP as the major products of snake-venom phosphodiesterase digestion. The temperature and pH optima for the enzyme were 25 degrees C and 8.5, respectively. The apparent Km value exhibited by the substrate NAD+, is 750 microM and the activity of the enzyme is inhibited by four chemical classes of inhibitors, nicotinamides, methylxanthines, thymidine and aromatic amides.
Mol Biochem Parasitol 1987 May
PMID:Detection of adenosine diphosphate-ribosyl transferase activity in the filarial worm, Onchocerca volvulus. 311 72

Two clones, pOA1 and pOA5, have been isolated from a genomic DNA library prepared from pools of Onchocerca armillata adults in the plasmid vector pUC12. In dot-blot hybridisations, these two clones do not cross-hybridise significantly with total genomic DNA from O. volvulus, O. gutturosa, O. ochengi, O. gibsoni, O. lienalis, bovine, human, Culicoides nubeculosus, Simulium species or Brugia pahangi, but do hybridise with as little as 100 pg of DNA from two separate geographic isolates of O. armillata. The sequence of pOA1 and pOA5 has been determined and found to contain a repetitive DNA sequence 147 bp in length. These clones can be used as specific and sensitive DNA probes for the identification of O. armillata capable of identifying a single L3 larva.
Mol Biochem Parasitol 1988 Sep
PMID:Cloning and characterization of a species-specific repetitive DNA sequence from Onchocerca armillata. 318 12

The objectives of the present study were to identify and characterize biochemically the major antigens of Brugia malayi microfilariae, a filarial parasite that infects humans. IgG antibodies in sera of mice which had cleared parasites from the bloodstream reacted with 30, 55, 94 and 150 kDa molecules of living microfilariae radioiodinated by the Iodo-bead method. Sera of humans infected with the related filariae Wuchereria bancrofti, Loa loa or Onchocerca volvulus immunoprecipitated molecules of similar size as well as two additional proteins of 22 and 43 kDa. Sera of uninfected North Americans or mice infected with Trichinella spiralis or Schistosoma mansoni did not recognize these radioiodinated antigens. Experiments to examine the possible surface localization and metabolism of these antigens showed that they were removed from intact parasites exposed to chymotrypsin or trypsin and that immunogenic molecules of 30, 55, and 150 kDa were released into excretory-secretory products by viable microfilariae. [35S]Methionine biosynthetically labeled polypeptide antigens of 22, 30, 35 and 150 kDa were detected by antibody reacted with intact microfilariae and/or their excretion products. Antigens of 30, 55, and 150 kDa appear to be glycoproteins as they bound wheat germ agglutinin and were biosynthetically labeled with [14C]N-acetyl-D-glucosamine. These data suggest that the surface of B. malayi microfilariae is a dynamic structure which synthesizes and sheds antigens.
Mol Biochem Parasitol 1987 Jan 15
PMID:Immunochemical characterization and biosynthesis of major antigens of iodo-bead surface-labeled Brugia malayi microfilariae. 357 45


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