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  • American Society for Microbiology  (61)
  • 1
    Online-Ressource
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    Monoclonal antibodies to human cytomegalovirus: three surface membrane proteins with unique immunological and electrophoretic properties specify cross-reactive determinants
    American Society for Microbiology ; 1982
    In:  Infection and Immunity Vol. 36, No. 3 ( 1982-06), p. 924-932
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 36, No. 3 ( 1982-06), p. 924-932
    Kurzfassung: Seventy-seven clones of hybridomas selected for reactivity by immunofluorescence with human cytomegalovirus (CMV)-infected cells were produced by fusing mouse myeloma cells with the spleen cells of mice immunized with CMV strain AD169. The clones were classified into seven groups on the basis of the electrophoretic properties of the polypeptides immune precipitated from extracts of CMV-infected cells. Studies on the three groups of monoclonal antibodies directed against CMV surface membrane antigens showed the following. Clones in each group were differentiated by immunoglobulin subclass, neutralizing activity, and reactivity with the antigenic domains of proteins exposed on the surface membranes of intact CMV-infected cells. Monoclonal antibodies in each group precipitated one slowly migrating protein and multiple faster migrating forms which shared antigenic determinants. The first group of monoclonal antibodies precipitated four glycosylated polypeptides with apparent molecular weights of 130,000, 110,000, 100,000, and 60,000. Monoclonal antibody CH51 of this group neutralized infectious virus but failed to react with antigenic domains on the surfaces of infected cells. The second group of monoclonal antibodies precipitated four polypeptides with apparent molecular weights of approximately 66,000, 55,000, 50,000, and 46,000. Monoclonal antibodies CH65 and CH134 in this group had neutralizing activity and reacted with antigenic domains of proteins exposed on the surface of CMV-infected cells. The third group of monoclonal antibodies precipitated four polypeptides with apparent molecular weights of 49,000, 48,000, 34,000, and 25,000. Serological analysis of 15 naturally occurring CMV strains with a panel of monoclonal antibodies to surface membrane proteins showed that the antigenic determinants reactive with the antibodies tested were conserved in all of the strains. Monoclonal antibodies to surface membrane proteins on CMV-infected cells may prove to be valuable reagents for identification of virus isolates.
    Materialart: Online-Ressource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/iai.36.3.924-932.1982
    RVK:
    XA 10000
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 1982
    ZDB Id: 1483247-1
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  • 2
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    Molecular Mechanism by Which the K70E Mutation in Human Immunodeficiency Virus Type 1 Reverse Transcriptase Confers Resistance to Nucleoside Reverse Transcriptase Inhibitors
    American Society for Microbiology ; 2007
    In:  Antimicrobial Agents and Chemotherapy Vol. 51, No. 1 ( 2007-01), p. 48-53
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 51, No. 1 ( 2007-01), p. 48-53
    Kurzfassung: The K70E mutation in human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) has become more prevalent in clinical samples, particularly in isolates derived from patients for whom triple-nucleoside regimens that include tenofovir (TNV), abacavir, and lamivudine (3TC) failed. To elucidate the molecular mechanism by which this mutation confers resistance to these nucleoside RT inhibitors (NRTI), we conducted detailed biochemical analyses comparing wild-type (WT), K70E, and K65R HIV-1 RT. Pre-steady-state kinetic experiments demonstrate that the K70E mutation in HIV-1 RT allows the enzyme to discriminate between the natural deoxynucleoside triphosphate substrate and the NRTI triphosphate (NRTI-TP). Compared to the WT enzyme, K70E RT showed 2.1-, 2.3-, and 3.5-fold-higher levels of resistance toward TNV-diphosphate, carbovir-TP, and 3TC-TP, respectively. By comparison, K65R RT demonstrated 12.4-, 12.0-, and 13.1-fold-higher levels of resistance, respectively, toward the same analogs. NRTI-TP discrimination by the K70E (and K65R) mutation was primarily due to decreased rates of NRTI-TP incorporation and not to changes in analog binding affinity. The K65R and K70E mutations also profoundly impaired the ability of RT to excise 3′-azido-2′,3′-dideoxythymidine monophosphate (AZT-MP) and other NRTI-MP from the 3′ end of a chain-terminated primer. When introduced into an enzyme with the thymidine analog mutations (TAMs) M41L, L210W, and T215Y, the K70E mutation inhibited ATP-mediated excision of AZT-MP. Taken together, these findings indicate that the K70E mutation, like the K65R mutation, reduces susceptibility to NRTI by selectively decreasing NRTI-TP incorporation and is antagonistic to TAM-mediated nucleotide excision.
    Materialart: Online-Ressource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.00683-06
    RVK:
    XA 24552
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 2007
    ZDB Id: 1496156-8
    SSG: 12
    SSG: 15,3
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  • 3
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    Nonnucleoside Reverse Transcriptase Inhibitor Hypersusceptibility and Resistance by Mutation of Residue 181 in HIV-1 Reverse Transcriptase
    American Society for Microbiology ; 2019
    In:  Antimicrobial Agents and Chemotherapy Vol. 63, No. 8 ( 2019-08)
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 63, No. 8 ( 2019-08)
    Kurzfassung: Substitutions at residue Y181 in HIV-1 reverse transcriptase (RT), in particular, Y181C, Y181I, and Y181V, are associated with nonnucleoside RT inhibitor (NNRTI) cross-resistance. In this study, we used kinetic and thermodynamic approaches, in addition to molecular modeling, to gain insight into the mechanisms by which these substitutions confer resistance to nevirapine (NVP), efavirenz (EFV), and rilpivirine (RPV). Using pre-steady-state kinetics, we found that the dissociation constant ( K d ) values for inhibitor binding to the Y181C and Y181I RT-template/primer (T/P) complexes were significantly reduced. In the presence of saturating concentrations of inhibitor, the Y181C RT-T/P complex incorporated the next correct deoxynucleoside triphosphate (dNTP) more efficiently than the wild-type (WT) complex, and this phenotype correlated with decreased mobility of the RT on the T/P substrate. Interestingly, we found that the Y181F substitution in RT—which represents a transitional mutation between Y181 and Y181I/V, or a partial revertant—conferred hypersusceptibility to EFV and RPV at both the virus and enzyme levels. EFV and RPV bound more tightly to Y181F RT-T/P. Furthermore, inhibitor-bound Y181F RT-T/P was less efficient than the WT complex in incorporating the next correct dNTP, and this could be attributed to increased mobility of Y181F RT on the T/P substrate. Collectively, our data highlight the key role that Y181 in RT plays in NNRTI binding.
    Materialart: Online-Ressource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.00676-19
    RVK:
    XA 24552
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 2019
    ZDB Id: 1496156-8
    SSG: 12
    SSG: 15,3
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  • 4
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    Online-Ressource
    Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Combined Species Identification and Drug Sensitivity Testing in Mycobacteria
    American Society for Microbiology ; 2017
    In:  Journal of Clinical Microbiology Vol. 55, No. 2 ( 2017-02), p. 624-634
    Details
    In: Journal of Clinical Microbiology, American Society for Microbiology, Vol. 55, No. 2 ( 2017-02), p. 624-634
    Kurzfassung: Species identification and drug susceptibility testing (DST) of mycobacteria are important yet complex processes traditionally reserved for reference laboratories. Recent technical improvements in matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) has started to facilitate routine mycobacterial identifications in clinical laboratories. In this paper, we investigate the possibility of performing phenotypic MALDI-based DST in mycobacteriology using the recently described MALDI Biotyper antibiotic susceptibility test rapid assay (MBT-ASTRA). We randomly selected 72 clinical Mycobacterium tuberculosis and nontuberculous mycobacterial (NTM) strains, subjected them to MBT-ASTRA methodology, and compared its results to current gold-standard methods. Drug susceptibility was tested for rifampin, isoniazid, linezolid, and ethambutol ( M. tuberculosis , n = 39), and clarithromycin and rifabutin (NTM, n = 33). Combined species identification was performed using the Biotyper Mycobacteria Library 4.0. Mycobacterium -specific MBT-ASTRA parameters were derived (calculation window, m/z 5,000 to 13,000, area under the curve [AUC] of 〉 0.015, relative growth [RG] of 〈 0.5; see the text for details). Using these settings, MBT-ASTRA analyses returned 175/177 M. tuberculosis and 65/66 NTM drug resistance profiles which corresponded to standard testing results. Turnaround times were not significantly different in M. tuberculosis testing, but the MBT-ASTRA method delivered on average a week faster than routine DST in NTM. Databases searches returned 90.4% correct species-level identifications, which increased to 98.6% when score thresholds were lowered to 1.65. In conclusion, the MBT-ASTRA technology holds promise to facilitate and fasten mycobacterial DST and to combine it directly with high-confidence species-level identifications. Given the ease of interpretation, its application in NTM typing might be the first in finding its way to current diagnostic workflows. However, further validations and automation are required before routine implementation can be envisioned.
    Materialart: Online-Ressource
    ISSN: 0095-1137 , 1098-660X
    URL: Article
    DOI: 10.1128/JCM.02089-16
    RVK:
    XA 10000
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 2017
    ZDB Id: 1498353-9
    SSG: 12
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  • 5
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    Mutations in the HIV-1 3′-Polypurine Tract and Integrase Strand Transfer Inhibitor Resistance
    American Society for Microbiology ; 2021
    In:  Antimicrobial Agents and Chemotherapy Vol. 65, No. 6 ( 2021-05-18)
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 65, No. 6 ( 2021-05-18)
    Materialart: Online-Ressource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.02432-20
    RVK:
    XA 24552
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 2021
    ZDB Id: 1496156-8
    SSG: 12
    SSG: 15,3
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  • 6
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    Structure and Dynamics of FosA-Mediated Fosfomycin Resistance in Klebsiella pneumoniae and Escherichia coli
    American Society for Microbiology ; 2017
    In:  Antimicrobial Agents and Chemotherapy Vol. 61, No. 11 ( 2017-11)
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 61, No. 11 ( 2017-11)
    Kurzfassung: Fosfomycin exhibits broad-spectrum antibacterial activity and is being reevaluated for the treatment of extensively drug-resistant pathogens. Its activity in Gram-negative organisms, however, can be compromised by expression of FosA, a metal-dependent transferase that catalyzes the conjugation of glutathione to fosfomycin, rendering the antibiotic inactive. In this study, we solved the crystal structures of two of the most clinically relevant FosA enzymes: plasmid-encoded FosA3 from Escherichia coli and chromosomally encoded FosA from Klebsiella pneumoniae (FosA KP ). The structure, molecular dynamics, catalytic activity, and fosfomycin resistance of FosA3 and FosA KP were also compared to those of FosA from Pseudomonas aeruginosa (FosA PA ), for which prior crystal structures exist. E. coli TOP10 transformants expressing FosA3 and FosA KP conferred significantly greater fosfomycin resistance (MIC, 〉 1,024 μg/ml) than those expressing FosA PA (MIC, 16 μg/ml), which could be explained in part by the higher catalytic efficiencies of the FosA3 and FosA KP enzymes. Interestingly, these differences in enzyme activity could not be attributed to structural differences at their active sites. Instead, molecular dynamics simulations and hydrogen-deuterium exchange experiments with FosA KP revealed dynamic interconnectivity between its active sites and a loop structure that extends from the active site of each monomer and traverses the dimer interface. This dimer interface loop is longer and more extended in FosA KP and FosA3 than in FosA PA , and kinetic analyses of FosA KP and FosA PA loop-swapped chimeric enzymes highlighted its importance in FosA activity. Collectively, these data yield novel insights into fosfomycin resistance that could be leveraged to develop new strategies to inhibit FosA and potentiate fosfomycin activity.
    Materialart: Online-Ressource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.01572-17
    RVK:
    XA 24552
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 2017
    ZDB Id: 1496156-8
    SSG: 12
    SSG: 15,3
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  • 7
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    Replication Fitness of Multiple Nonnucleoside Reverse Transcriptase-Resistant HIV-1 Variants in the Presence of Etravirine Measured by 454 Deep Sequencing
    American Society for Microbiology ; 2013
    In:  Journal of Virology Vol. 87, No. 15 ( 2013-08), p. 8805-8807
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 87, No. 15 ( 2013-08), p. 8805-8807
    Kurzfassung: We applied an efficient method to characterize the relative fitness levels of multiple nonnucleoside reverse transcriptase (NNRTI)-resistant HIV-1 variants by simultaneous competitive culture and 454 deep sequencing. Using this method, we show that the Y181V mutation in the HIV-1 reverse transcriptase in particular confers a clear selective advantage to the virus over 14 other NNRTI resistance mutations in the presence of etravirine in vitro .
    Materialart: Online-Ressource
    ISSN: 0022-538X , 1098-5514
    URL: Article
    DOI: 10.1128/JVI.00335-13
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 2013
    ZDB Id: 1495529-5
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  • 8
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    Antibody response to cytomegalovirus polypeptides captured by monoclonal antibodies on the solid phase in enzyme immunoassays
    American Society for Microbiology ; 1985
    In:  Journal of Clinical Microbiology Vol. 21, No. 4 ( 1985-04), p. 517-521
    Details
    In: Journal of Clinical Microbiology, American Society for Microbiology, Vol. 21, No. 4 ( 1985-04), p. 517-521
    Kurzfassung: Antibodies to different cytomegalovirus (CMV) polypeptide antigens, captured by monoclonal antibodies coated on the solid phase of an enzyme immunoassay test, were analyzed in 42 serum pairs submitted for serodiagnosis of CMV infection. Three CMV antigens, captured on the solid phase by three monoclonal antibodies of different specificities, designated CH92-1, CH65-1, and CH16-1, were glycoproteins A (gA), gC, and gD, respectively; and one antigen, captured by CH23, was a polypeptide with an apparent molecular weight of 150,000, possibly associated with the nucleocapsid. Of these four CMV antigens, gA captured by CH92-1 was most effective in eliciting an antibody response. Antibody to this antigen was present in serum samples at a higher concentration in primary and reactivated infection and persisted longer than did antibody to the other tested antigens. In contrast, antibody to antigen captured by CH23 was at a lower concentration, rose more slowly in infection, and persisted for a shorter time than did antibody to the other antigens. Antibody response to gC and gD was intermediate in concentration and temporal appearance compared with the antibody response to gA and to the polypeptide bound by CH23. An enzyme immunoassay on paired serum samples with the captured glycoproteins as antigen was equal for the detection of current infection to an enzyme immunoassay with the whole CMV antigen from infected cell lysates. Enzyme immunoassays with either the CMV glycoproteins or the whole CMV antigen from infected cell lysates were superior to a complement fixation test with a glycine extract antigen for serodiagnosis of current infection.
    Materialart: Online-Ressource
    ISSN: 0095-1137 , 1098-660X
    URL: Article
    DOI: 10.1128/jcm.21.4.517-521.1985
    RVK:
    XA 10000
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 1985
    ZDB Id: 1498353-9
    SSG: 12
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  • 9
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    Evaluation and reporting of enzyme immunoassay determinations of antibody to herpes simplex virus in sera and cerebrospinal fluid
    American Society for Microbiology ; 1982
    In:  Journal of Clinical Microbiology Vol. 15, No. 5 ( 1982-05), p. 815-823
    Details
    In: Journal of Clinical Microbiology, American Society for Microbiology, Vol. 15, No. 5 ( 1982-05), p. 815-823
    Kurzfassung: Several methods for evaluating and reporting enzyme immunoassay (EIA) determinations of antibody to herpes simplex virus derived from one dilution of single serum samples were studied. An EIA ratio method for serological evidence of current infection from paired serum samples was also evaluated. Optical density (OD) of the reaction at a 1:100 serum dilution and estimated titers obtained by reference of the OD of the serum dilution to a standard curve were compared to the corresponding plotted EIA titer obtained by titration to endpoint. Neither the OD per se nor the estimated titer was completely predictive of the plotted titer (correlation coefficient [r] of 0.824 and 0.817, respectively), and they provided only a semiquantitative measurement of antibody concentration. For an antibody status report, however, OD would be sufficient if related to the cutoff value as an EIA index (OD of sample divided by cutoff OD for positive specimens). The OD of the EIA reaction at a single dilution (1:5) of cerebrospinal fluid, on the other hand, correlated quite well with the titer obtained by titration (r = 0.950). For serological diagnosis of current infection, the OD ratio of convalescence-phase/acute-phase sera was determined at several dilutions. A ratio of greater than or equal to 1.54 was calculated as a reliable index for a significant rise in antibody concentration and compatibl e with current infection. By determining the convalescent-phase/acute-phase serum ratio at two dilutions, 1:100 and 1:1,000, the EIA ratio method appeared to be a sensitive as or more sensitive than, complement fixation in diagnosing current infection.
    Materialart: Online-Ressource
    ISSN: 0095-1137 , 1098-660X
    URL: Article
    DOI: 10.1128/jcm.15.5.815-823.1982
    RVK:
    XA 10000
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 1982
    ZDB Id: 1498353-9
    SSG: 12
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  • 10
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    Enzyme immunoassay versus plaque neutralization and other methods for determination of immune status to measles and varicella-zoster viruses and versus complement fixation for serodiagnosis of infections with those viruses
    American Society for Microbiology ; 1985
    In:  Journal of Clinical Microbiology Vol. 21, No. 6 ( 1985-06), p. 869-874
    Details
    In: Journal of Clinical Microbiology, American Society for Microbiology, Vol. 21, No. 6 ( 1985-06), p. 869-874
    Kurzfassung: Results by an enzyme immunoassay method (EIA) performed at one serum dilution and results by indirect immunofluorescence (IFA) and hemagglutination inhibition (HI) tests performed at step dilutions were correlated with results by a neutralization test (50% plaque neutralization [PN]) performed at step dilutions on single serum samples for serologic evaluation of immunity status to measles virus. PN results were taken as true indicators of immunity, and the other tests were evaluated on that basis. The predictive value of a positive result being positive also by PN was 95.3% for HI and 93.3% for EIA and IFA. The predictive value of a negative result being negative also by PN was 81.1% for HI, 100% for EIA, and 75.0% for IFA. A similar study on immunity status to varicella-zoster virus by EIA and by an anticomplement immunofluorescence test versus PN showed a 100% predictive value of a positive or negative result by EIA. By the anticomplement immunofluorescence test, the predictive value of a positive result was 97.7%, and that of a negative result was 88.5%. Studies on the comparative ability of EIA versus complement fixation (CF) to detect significant changes in antibody concentration between acute-phase and convalescent-phase serum samples indicative of a current infection were also done. Both tests were satisfactory for the serodiagnosis of measles or varicella-zoster virus infections. However, EIA was preferable to CF because it was less technically difficult, less labor intensive, and could be performed on sera that were anticomplementary in CF reactions.
    Materialart: Online-Ressource
    ISSN: 0095-1137 , 1098-660X
    URL: Article
    DOI: 10.1128/jcm.21.6.869-874.1985
    RVK:
    XA 10000
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 1985
    ZDB Id: 1498353-9
    SSG: 12
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