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G Utter

Publications and source records attributed to G Utter.

At least 37 records · Page 2Linked to original sources
PubMed1989

Analysis of a subclass-restricted HIV-1 gp41 epitope by omission peptides.

To define the amino acids involved in IgG subclass reactivity to two overlapping HIV-1 gp41 (E34/32; amino acid positions 582-613) peptides, sera from 18 HIV-infected individuals were studied. Peptides mimicking E34 but with single amino acid deletions or glycine substitutions were used to define the amino acid residues necessary for antibody binding. Two dominating immunogenic epitopes, containing highly hydrophilic amino acids, were found on the original peptide. Further analysis was undertaken with two corresponding omission sets of dodecapeptides representing halves of the complete E34 plus a terminal cystein peptide. The subclass reactivities usually differed between the patients with regard to the epitopes with which the different IgG subclasses reacted and also to the importance of different amino acids in antibody binding. The 600 glycine and the 601 lysine were involved in the binding of all IgG1, 2 and 4 and most IgG3. The development of E34/32-reactive IgM and IgG subclasses showed different patterns in four patients with primary HIV infections, contradicting the existence of a general pattern for the development of IgG subclasses to this peptide. The findings suggest that different progenitor clones are selected for synthesis of the different subclasses.

Amino Acid Sequence↗
PubMed1986

Detection of antigen in immune precipitates by silver staining of SDS-polyacrylamide gels.

The silver staining technique of Merril et al. (1981) was used to identify antigens separated by SDS-PAGE after dissociation of immune complexes purified by absorption with staphylococcus A protein. The five and four dominating structural components of measles and RS virus (Mr range 28,000 to 79,000) respectively precipitated with monoclonal antibodies were readily identified, except when the Mr of the virus-specific antigen was in the same range as immunoglobulin heavy and light chains. Specific antigens were identified less effectively after precipitation with polyclonal sera because of a larger background of stainable proteins. This method, which combines the sensitivity and high resolution of silver staining and the specificity of immune complexing with monoclonal antibodies, is rapid and inexpensive.

Antibodies, Monoclonal↗
PubMed1986

Protection against canine distemper virus in dogs after immunization with isolated fusion protein.

Canine distemper virus attachment (hemagglutinin [H] equivalent) and fusion (F) antigens were purified by affinity chromatography with monoclonal antibodies. The purified antigens were used to immunize groups of three dogs. Radioimmune precipitation assays with sera from these animals showed that the F antigen preparation was pure and induced only an F polypeptide-specific antibody response but that the H antigen preparation had a slight contamination by the F antigen. Immunized animals were challenged with virulent canine distemper virus. Two animals in each group developed pronounced humoral and cellular immune responses after challenge. Among these infected animals, only the dogs immunized with H antigen developed symptoms, albeit mild. In contrast, three nonimmunized control animals developed severe disease, with a fatal outcome in two cases. The complete resistance against challenge in two dogs was interpreted to reflect in one case anti-F immunity and in the other case most likely a high level of anti-H immunity. It is suggested that the F antigen may be of particular interest for the development of morbillivirus and possibly other paramyxovirus subunit or synthetic vaccines, because it can induce immunity capable of blocking virus infection and in situations of virus replication prevent the emergence of symptoms.

Animals↗
PubMed1984

Purification, morphology and antigenic characterization of measles virus envelope components.

Measles virus haemagglutinin (H), fusion (F) and matrix (M) components were purified by affinity chromatography using monoclonal antibodies coupled to CNBr-activated Sepharose. H and M proteins were purified to homogeneity as determined by polyacrylamide gel electrophoresis by a single cycle of adsorption-desorption. The corresponding purification of the F protein required two cycles of adsorption-desorption. After the second adsorption an extra wash with 1 M-guanidine-HCl was employed to remove the contaminating cellular actin. Electron microscopic examination of the purified envelope proteins showed that, at pH 6.0, the H peplomers had a truncated conical shape (width 6.5 to 4 nm, length 16 nm), and the F peplomers had a club-like shape (dimensions of the oval head 6 X 9 nm, length 15 nm). Lengths of both peplomers were measured excluding their undiscernible hydrophobic part. The M component at pH 3.0 appeared as a rounded particle (diam. 8 nm, central accumulation of contrast 1.5 nm) suggested to include four to six M polypeptides. Rabbit hyperimmune sera were prepared against all three purified envelope components. These sera reacted only with the homologous antigen in radioimmunoprecipitation assays. Both antisera against the H and F components neutralized the virus and blocked virus-specific haemolysis, but only anti-H serum inhibited haemagglutination.

Animals↗
PubMed1984

The influence of specific antibodies and complement on the motility and the viability of Entamoeba histolytica trophozoites.

The distribution of peroxidase-labeled normal or specific rabbit immunoglobulin (Ig) in Entamoeba histolytica trophozoites was studied by transmission electron microscopy. Small amounts of normal Ig became attached to the cell surface but did not redistribute. Internalized specific Ig was firmly bound to the inner membranes of phagocytosis vacuoles, while aggregates of normal Ig were dispersed over the vacuolar lumen. The distribution of fluorescein isothiocyanate-labeled Ig in living amebae was correlated with the cell motility at different times. Immobilization coincided with the cellular metabolic processing of internalized material. Remobilization occurred when the Ig was degraded and antibodies again bound to the reappearing surface antigens. E. histolytica activated complement by the classical pathway. Fresh guinea pig serum alone did not produce lysis which, however, did occur when it was added together with normal rabbit Ig. Normal rabbit Ig may constitute a complement-fixing substrate and activate complement by the classical pathway. Immobilization of the amebae by cytochalasin B (10 micrograms/ml) increased the susceptibility to cytolytic effects of specific antibodies or complement, or both. Pharmacological inhibition of cell motility might augment the immunological defence of the host against amebic infection.

Animals↗
PubMed1983

Antigenicity of Entamoeba histolytica strain nih 200: a survey of clinically relevant antigenic components.

The molecular weights of the major polypeptides of Entamoeba histolytica NIH 200 soluble whole extract, and its five fractions eluted from a Sephadex G-200 column, were in the range 150,000-9,000 daltons according to sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Autoradiography of SDS-PAGE analysis of 125I surface-labeled amebae revealed more than 12 bands, eight of which corresponded to those recovered in soluble extract. Considering the pronounced phagocytosis and the rapid cell membrane turnover of the ameba, it seems likely that the same antigenic components would be present both on and within the ameba at different stages. The first four gel-filtered fractions were immunogenic and showed non-identical precipitates with sera from 12 Swedish and 12 Ethiopian patients with verified amebic disease. Seven polypeptides in the whole extract reacted with human anti-ameba IgG covalently bound to CNBr activated Sepharose 4B. Immune replica (Western blotting) of SDS-PAGE of whole extract produced by human anti-ameba antisera demonstrated eight bands. The response to the different amebic antigens was not correlated to clinical symptoms, duration of illness or origin of ameba strain. Thus the present results did not support the use of purified fractions rather than the whole soluble extract for diagnostic tests.

Antigen-Antibody Complex↗
PubMed1982

Non-specific precipitin reactions of IgG at low ionic strength.

Precipitin reactions apparently not involving specific antibodies were obtained in immunodiffusion experiments performed at low salt concentration between IgG and the muscle proteins, actin and tropomyosin. The precipitates, which dissolved at physiologic ionic strength, may result from electrostatic interaction of molecules of different net charge and different distribution and number of charged groups.

Actins↗
PubMed1982

Further characterization of the Ca2+-dependent F-actin-depolymerizing protein of human serum.

The F-actin-depolymerizing factor (ADF) of human serum was purified and identified as a 93000-daltons protein. The concentration of ADF was calculated to 120-150 micrograms/ml in four normal sera and about half as much in three sera from leukemia patients treated with cytostatic drugs. In the presence of Ca2+ ADF shortened actin filaments into fragments, the size of which was correlated to the actin: ADF molar ratio, as judged by electron microscopy. The severing of F-actin was not necessarily followed by an increase in the quantities of monomeric actin, as determined by a DNase I inhibition assay and a sedimentation assay. The findings indicated that ADF shortens filamentous actin by breaking bonds between adjacent actin molecules thereby forming stable ADF-actin complexes, without a monomeric net release. The effect of ADF on F-actin was rapid and was reversed upon chelation of Ca2+. ADF cross-reacted immunologically and exhibited similarity in reaction mechanism with gelsolin, the Ca2+-dependent F-actin-severing protein from macrophages. This implies that the proteins are both structurally and functionally related. The physiological role of ADF may be to handle actin released at cell destruction, probably by forming ADF-G-actin 1:1 complexes thereby preventing formation of actin filaments.

Actin Depolymerizing Factors↗
PubMed1981

Three sets of actin filaments in sensory cells of the inner ear. Identification and functional orientation determined by gel electrophoresis, immunofluorescence and electron microscopy.

Receptor cells in the ear are mechanically excited through displacement of sensory hairs, stereocilia, in relation to a sub-surface platform, the cuticular plate, into which rootlets of the stereocilia insert. The presence of actin in inner ear sensory organs and receptor cells was established by gel electrophoresis, by labelling with antibodies against actin, and by electron microscopy after decoration with subfragment-1 of myosin. The latter method was used to determine the functional orientation of actin filaments found to be present in the mechanosensitive region of the receptor cells. Actin filaments were demonstrated in the stereocilia and their rootlets, in the cuticular plate and in relation to the zonula adherens surrounding the top of the cell. Filaments which run parallel to the cell surface were found in the cuticular plate and zonula adherens. Some filaments associated with the zonula adherens had a functional orientation opposite to that of more centrally located filaments in the cuticular plate. A structural complex consisting of a solid filament surrounded by actin filaments in hexagonal packing was found in the periphery of the cuticular plate. The possibility is suggested that the central filament is myosin.

Actins↗
PubMed1981

A radioimmunoassay for determination of anti-actin antibodies.

The reaction of spontaneously occurring human anti-human antibodies and experimentally produced rabbit anti-actin antibodies was investigated in a solid-phase radioimmunoassay (RIA). Three structurally different in vitro forms of actin monomeric G-actin filamentous F-actin and aggregated denatured actin were used as antigens. Human anti-actin antibodies reacted with F- and G-actin but not with aggregated actin, while rabbit anti-actin antibodies gave a strong reaction with all 3 forms of actin indicating differences in antibody specificities. The results of the anti-actin RIA were compared with those obtained by indirect immunofluorescence (IFL) on cryostat sections of rat stomach. The anti-actin RIA discriminated between patients' sera and control sera in most cases, although the indirect IFL test gave more conclusive results. The seemingly low sensitivity of the anti-actin RIA compared with that of indirect IFL test for detection of human anti-actin antibodies is probably due to favourable antigen distribution in tissue, not available in the solid phase. The anti-actin RIA was able to detect anti-actin antibodies in 8 out of 8 immunized rabbits although only two produced antibodies detectable by indirect IFL. The differences in reactivity between the two methods may depend on the presence of aggregated denatured actin in the antigen preparation used for immunization and exposure of the corresponding antigenic determinants of actin on the solid phase.

Actins↗
PubMed1979

F-Actin-depolymerizing activity of human serum.

Non-heated human and animal sera contain a factor which exhibited an inhibiting activity on the staining of actin-containing structures by anti-actin antibodies in indirect immunofluorescence experiments. The presence of this factor lowered the viscosity of F-actin preparations and caused, as studied by electron-microscopy, a depolymerization of F-actin filaments as well as inhibition of filament formation of G-actin. The factor was, after its reaction with F-actin, liberated seemingly unaffected, indicating an enzymatic activity. The factor tentatively termed 'F-actin depolymerizing factor' was heat-sensitive and trypsin sensitive but resisted reduction. It was Ca2+ dependent and the staining inhibiting reaction was faster at 30 degrees C and 37 degrees C than at lower temperatures. Gel filtration experiments on Sephadex G-200 suggested a molecular size of the actin depolymerizing factor slightly higher than that of albumin. The electrophoretic mobility was that of gamma 2 globulin. The physiological role of the factor might be to prevent the presence of F-actin filaments within the circulation.

Actins↗
PubMed1978

Purification of hepatitis B surface antigen by affinity chromatography.

Hepatitis B surface antigen (HBsAg), was purified from plasma by affinity chromatography on matrix-bound sulphated carbohydrates such as heparin or dextran sulphate. Further purification by precipitation with polyethylene glycol (PEG) 6000 resulted in a highly purified HBsAg preparation. The overall recovery amounted to about 70% of the total antigen content of the starting plasma. Electron microscopic data revealed mainly 22 nm spherical particles accompanied by few or no filaments. The process is simple, rapid and lends itself readily to large-scale applications.

Chromatography, Affinity↗