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

We report here a panel of cDNA clones from Onchocerca volvulus which were isolated on the basis of being uniquely recognised by onchocerciasis sera and not by sera from patients infected with the major lymphatic filarial nematode parasite Wuchereria bancrofti. Over 90% of O. volvulus recombinants from a primary screen were found to cross-react with lymphatic filariasis sera and were discarded. The subset of specific clones, selected with pooled sera, was then screened with panels of individual patient sera. Individual onchocerciasis cases showed a highly heterogeneous pattern of recognition of recombinant peptides, but several clones were identified which could be combined in a cocktail of antigenic epitopes to successfully detect all infected cases in the study. All these clones encode low molecular weight proteins of the parasite, confirming earlier reports that antigens of this size class show greater species specificity. Several clones encode proteins of 20-23 kDa, the same molecular weight range as the major surface protein of adult worms. The two most commonly recognised clones, Ov22/31M and Ov20/36M were subcloned into the vector pNGS 8 which produces fusion proteins attached to a polyasparagine leader. The fusion peptides of both Ov22/31M and Ov20/36M were soluble and easily purified by gel filtration. Purified fusion protein was used in ELISA to assess reactivity of infected patients giving 90% sensitivity with 100% specificity.
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PMID:cDNA clones of Onchocerca volvulus low molecular weight antigens provide immunologically specific diagnostic probes. 192 97

By using radioiodination methods which are thought to label preferentially the surface followed by SDS-PAGE and autoradiography, components of different developmental stages of O. volvulus have been identified. Between 2 and 10 polypeptide antigens were revealed on infective larvae (L3), females, males, eggs, nodular and skin microfilariae by using immunoblotting assays with human onchocerciasis sera. Antigen recognition did not vary with the density of skin microfilariae in the patients from whom the sera were obtained. Some of the antigens seemed to be stage specific; for example, antigens of 31 kDa which were detected only on skin microfilariae, or the 67.5 and 25 kDa components that occurred on the adult females, but were absent from adult males. Some of these antigens were also identified as glycoproteins. A 68 kDa glycoprotein was found in adult females, males and nodular microfilariae. Two glycoproteins of 74 and 45 kDa were found on egg shells, and a 18.5 kDa glycoprotein was recovered from L3. Type VI collagen was found with a specific antiserum on skin microfilariae, but not on eggs and females. Laminin was found on nodular mf. It is concluded that the changing antigenic profiles of the worm stages and the coating of these worms with connective tissue epitopes contribute to the evasion of host immunity.
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PMID:Identification of different radiolabelled antigens of the developmental stages of Onchocerca volvulus. 197 31

We compared the chemical and immunological properties of cuticular collagens from four species of filarial nematodes, Onchocerca volvulus, O. gutturosa, Brugia malayi, and Dirofilaria immitis. The electrophoretic mobility of the major polypeptides extracted from adult worms is characteristic for each species studied. Cuticular collagens from adult worms and infective larvae differ in their susceptibility to proteases that cleave vertebrate collagens and to collagenases prepared from different developmental stages of filarial parasites. The overall amino acid composition of filarial collagens resembles that of vertebrate interstitial collagens and differs from that reported for collagens from free-living or intestinal nematodes. However, cuticular proteins of the four filarial species studied significantly differed in amino acid composition and in their reactivity with antisera to interstitial and basement membrane collagens of vertebrates.
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PMID:Onchocerca volvulus, O. gutturosa, Brugia malayi, and Dirofilaria immitis: a comparative study of the immunochemical properties of cuticular proteins from filarial parasites. 200 21

Several members of a series of 2-acetylpyridine thiosemicarbazones possess in vivo and in vitro macrofilaricidal properties. The most promising of the group tested is N4-(2-aminophenyl)-2-[1-(2-pyridinyl)ethylidene]-hydrazinecarbothioam ide (4), which suppressed 100% of the macrofilariae of Brugia pahangi and 94% of those of Acanthocheilonema viteae in the jird at a dose of 25 mg/kg per day x 5. Compounds 4 and 14 were also shown to inactivate or kill Onchocerca gutturosa and Onchocerca volvulus adult worms as measured by the loss of their motility or the inhibition of the conversion by the worms of the dye MTT to formazan.
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PMID:2-acetylpyridine thiosemicarbazones. 13. Derivatives with antifilarial activity. 201 17

The population from five Guatemalan plantations in areas endemic for onchocerciasis was surveyed, and 1032 individuals were recruited to participate in our study. From physical examination, past clinical history (5 to 8 yr), laboratory evidence and sample availability, a group of 778 long term residents with confirmed disease status were selected for detailed examination. We were able to identify 268 long term residents of endemic areas who had never been infected, 44 of these are from hyper- and mesoendemic areas. The 44 uninfected individuals from the hyper- and mesoendemic areas, because of their considerable exposure to this disease, were classified as "putatively immune." Intact nodules containing adult worms of Onchocerca volvulus were homogenized in the presence of protease inhibitors and fractionated into particulate and aqueous isotonic soluble antigens. Systematic analysis of these Ag fractions showed considerable amounts of Ig, presumably associated with Ag in the form of immune complexes. Individual specific antibody reactions from all 778 patients to nodule Ag were examined. Reactions to O. volvulus antigens by antibodies from patients with confirmed parasitic infections were almost exclusively restricted to IgG1 and IgG4 isotypes. Antigenic activity appeared to be primarily associated with low molecular mass (14 to 29 kDa) components. Some competitive blocking of antibody activities of other isotypes by IgG1 was observed, most notable was that of IgG3 and IgA. IgG4 and IgM activities were not significantly blocked.
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PMID:Guatemalan human onchocerciasis. I. Systematic analysis of patient populations, nodular antigens, and specific isotypic reactions. 203 67

The isolation and characterization of a recombinant cDNA clone (OV7) expressing an antigen present in Onchocerca volvulus infective larvae and adult stages is described. Using chimpanzee antiserum generated against irradiated infective larvae, we isolated a cDNA clone from a lambda gt11 cDNA expression library derived from adult O. volvulus mRNA. The open reading frame encodes 131 amino acids corresponding to a 15.2-kDa protein. Affinity purified antibodies which bound specifically to OV7 fusion polypeptide recognized a single antigen with an apparent molecular weight of 17,000 in extracts of L3, L4 and adult worms. Immunoelectron microscopy established that the antigen encoded by this clone is present in the hypodermis and the basal layer of the cuticle of L3 and female adult worm, and in the egg shell around developing microfilariae. Since the OV7 fusion polypeptide is onchocerca-specific and is recognized specifically by sera from onchocerciasis patients, and sera from non-patent but infected chimpanzees, and not by sera from patients with other filarial parasites, it may have potential as an antigenic component in a test for detection of non-patent and patent infections of O. volvulus. The OV7 amino acid sequence contains residues that have a probable homology with the cysteine proteinase inhibitor superfamily.
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PMID:Characterization of an Onchocerca volvulus cDNA clone encoding a genus specific antigen present in infective larvae and adult worms. 205 41

Twenty patients from an area of vector control in the savannah region of northern Ghana with moderate to heavy infection with Onchocerca volvulus were randomised to receive two priming doses of levamisole 150 mg on two occasions followed either by mebendazole-citrate (500 mg) given daily or twice daily for 14 days. The two dose levels produced a similar effect on skin microfilariae (80-88% reduction) with a very mild systemic clinical reaction: low levels were maintained over 42 weeks. Both regimes were embryotoxic for O. volvulus; an effect which was transient in the single dose group but persisted for more than three months in the twice daily dose group. Mebendazole-citrate appeared to be absorbed more predictably than has been observed previously for mebendazole. The degree of systemic exposure as determined by measurement of AUC (0-24 h) was 2.5 times greater for the twice daily dose as compared to the single dose and this fact was reflected in the efficacy of the two dose regimes against the adult female worms at three months.
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PMID:The chemotherapy of onchocerciasis. XIV. Studies with mebendazole citrate. 207 82

Onchocerca volvulus worms, extracted from nodules by collagenase digestion, stained with haematoxylin and cleared in glycerol, were unravelled for longitudinal examination and later embedded in brain blocks for study of serial transverse sections. A classification system for female worms is proposed, based on the reproductive status of 446 worms from Guatemala, 94 from Liberia and 125 from Mali. They were categorized into fecund, inseminated specimens; uninseminated, but potentially fertile specimens, shedding ova destined to degenerate; worms changing from the uninseminated to the inseminated state and vice versa, which were few in number; old worms, with degenerate ovaries, whose genital tracts were either empty or had disappeared; and moribund or dead worms, characterized by loss of turgor, collapse and degeneration, calcification, or invasion by polymorphic, basophilic cells. Potentially fertile worms shed oocytes continuously and, when they were inseminated, embryonic development ensured. No evidence was found of a periodic cycle of reproduction. Inseminated worms were found in nodules without a male worm, and uninseminated worms in nodules harbouring male worms. Measurements are recorded of portions of the female reproductive tract and of the length of uterus occupied by the various embryonic stages in fully fecund worms. A significant difference in the length of the body behind the first and second ovaries was observed as between worms from West African savanna (Mali) and forest (Liberia). Limited observations were also made on meiosis in the oocyte, penetration of the oocyte by sperm, formation of the ovum, syngamy and zygote formation.
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PMID:On the reproductive activity of the female Onchocerca volvulus. 207 83

Immunoelectroblotting and enzyme-linked immunosorbent assay were used to identify non-cross-reacting antigenic components of Dracunculus medinensis and the filarial worms Onchocerca volvulus, Loa loa, Wuchereria bancrofti, Brugia malayi, and Mansonella ozzardi. Parasite specific serodiagnostic ELISA systems for onchocerciasis and dracunculiasis were devised based on these findings. Phosphate buffered saline extracts of adult worms were passed through a column of monoclonal antibodies to phosphorylcholine (PC). Crude and PC-depleted extracts were reacted on ELISA plates with individual sera from subjects infected with a range of nematodes. Binding of total antibody (Ig) or IgG class antibody and IgG4 subclass antibody was revealed using goat antihuman-Ig-phosphatase conjugate, or appropriate mouse monoclonal antihuman-Ig-type-specific reagents, followed by goat antimouse-Ig-phosphatase conjugate. Specificity of ELISA was improved by restricting reaction to the host's IgG4 antibody subclass, and/or by removing PC determinants from crude antigens. In parallel immunoelectroblots, crude and PC-depleted extracts probed with pooled sera showed potentially useful diagnostic antigens, including a 12 kDa protein from D. medinensis and 14, 18, and 27 kDa proteins from O. volvulus. Two Onchocerca specific ELISA systems non-reactive with antibodies to D. medinensis were devised.
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PMID:Specific and cross-reacting antibodies in human responses to Onchocerca volvulus and Dracunculus medinensis infections. 213 30

In order to identify Onchocerca volvulus antigens that could be considered as either diagnostic and/or immunoprophylactic, mouse monoclonal antibodies were produced against O. volvulus soluble antigens. Three were selected on the basis of their staining patterns in an indirect fluorescent antibody assay carried out on cryosections of adult O. volvulus. The first monoclonal antibody (K1-159) recognized a cuticular antigen which appeared in IFA to be restricted to the genus Onchocerca. However, neither Western blotting, nor the immunoprecipitation experiments performed on radiolabelled O. volvulus soluble antigen allowed detection of the corresponding antigen(s). The second monoclonal antibody (K1-126) bound to the muscle cells of adults. A 30,000 Mr antigen was detected by Western blot analysis of adult O. volvulus homogenate. This antigen was also recognised by sera from infected patients and corresponding antigenic determinants were detected in extracts of O. gutturosa, Acanthocheilonema viteae and Ascaris suum, but not in Brugia malayi. The third monoclonal antibody (K1-143) recognized egg shells and the surface of adult worms. The target epitope was not species specific and could be found in O. gutturosa, A. viteae, B. malayi and A. suum. The electrophoretic analysis of I-125 labelled soluble antigens and radiolabelled surface antigens of adult O. volvulus, showed numerous antigens (molecular weights ranging from 30,000 to 120,000 Mr) precipitated by K1-143. In an inhibition radioimmunoassay, K1-143 allowed the detection of corresponding antibodies in 79% of the O. volvulus patient sera tested.
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PMID:Use of monoclonal antibodies for the characterization of Onchocerca volvulus antigens. 218 26


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