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  • American Society for Microbiology  (10)
  • 1995-1999  (10)
  • 1
    Online Resource
    Online Resource
    Characterization of Activity and Expression of Isocitrate Lyase in Mycobacterium avium and Mycobacterium tuberculosis
    American Society for Microbiology ; 1999
    In:  Journal of Bacteriology Vol. 181, No. 23 ( 1999-12), p. 7161-7167
    Details
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 181, No. 23 ( 1999-12), p. 7161-7167
    Abstract: Analysis by two-dimensional gel electrophoresis revealed that Mycobacterium avium expresses several proteins unique to an intracellular infection. One abundant protein with an apparent molecular mass of 50 kDa was isolated, and the N-terminal sequence was determined. It matches a sequence in the M. tuberculosis database (Sanger) with similarity to the enzyme isocitrate lyase of both Corynebacterium glutamicum and Rhodococcus fascians . Only marginal similarity was observed between this open reading frame (ORF) (termed icl ) and a second distinct ORF (named aceA ) which exhibits a low similarity to other isocitrate lyases. Both ORFs can be found as distinct genes in the various mycobacterial databases recently published. Isocitrate lyase is a key enzyme in the glyoxylate cycle and is essential as an anapleurotic enzyme for growth on acetate and certain fatty acids as carbon source. In this study we express and purify Icl, as well as AceA proteins, and show that both exhibit isocitrate lyase activity. Various known inhibitors for isocitrate lyase were effective. Furthermore, we present evidence that in both M. avium and M. tuberculosis the production and activity of the isocitrate lyase is enhanced under minimal growth conditions when supplemented with acetate or palmitate.
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    URL: Article
    DOI: 10.1128/JB.181.23.7161-7167.1999
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1999
    detail.hit.zdb_id: 1481988-0
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Infectious Clones and Vectors Derived from Adeno-Associated Virus (AAV) Serotypes Other Than AAV Type 2
    American Society for Microbiology ; 1998
    In:  Journal of Virology Vol. 72, No. 1 ( 1998-01), p. 309-319
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 72, No. 1 ( 1998-01), p. 309-319
    Abstract: Adeno-associated viruses (AAVs) are single-stranded dependent parvoviruses being developed as transducing vectors. Although at least five serotypes exist (AAV types 1 to 5 [AAV1 to -5]), only AAV2, AAV3, and AAV4 have been sequenced, and the vectors in use were almost all derived from AAV2. Here we report the cloning and sequencing of a second AAV3 genome and a new AAV serotype designated AAV6 that is related to AAV1. AAV2, AAV3, and AAV6 were 82% identical at the nucleotide sequence level, and AAV4 was 75 to 78% identical to these AAVs. Significant sequence variation was noted in portions of the capsid proteins that presumably are responsible for serotype-specific functions. Vectors produced from AAV3 and AAV6 differed from AAV2 vectors in host range and serologic reactivity. The AAV3 and AAV6 vector serotypes were able to transduce cells in the presence of serum from animals previously exposed to AAV2 vectors. Our results suggest that vectors based on alternative AAV serotypes will have advantages over existing AAV2 vectors, including the transduction of different cell types, and resistance to neutralizing antibodies against AAV2. This could be especially important for gene therapy, as significant immunity against AAV2 exists in human populations and many protocols will likely require multiple vector doses.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    URL: Article
    DOI: 10.1128/JVI.72.1.309-319.1998
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1998
    detail.hit.zdb_id: 1495529-5
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  • 3
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    Online Resource
    High-Fidelity Correction of Mutations at Multiple Chromosomal Positions by Adeno-Associated Virus Vectors
    American Society for Microbiology ; 1999
    In:  Journal of Virology Vol. 73, No. 9 ( 1999-09), p. 7376-7380
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 73, No. 9 ( 1999-09), p. 7376-7380
    Abstract: The gene targeting techniques used to modify chromosomes in mouse embryonic stem cells have had limited success with many other cell types, especially normal primary cells with restricted growth capacity outside the organism. This is due in large part to the technical problems and/or inefficiency of conventional DNA transfer methods, as well as the low rates of homologous recombination obtained in unselected cell populations. We recently described an alternative approach in which adeno-associated virus (AAV) vectors were used to modify homologous chromosomal sequences, and targeting rates close to 1% were observed at the single copy hypoxanthine phosphoribosyl transferase (HPRT) locus in normal human cells (D. W. Russell and R. K. Hirata, Nat. Genet. 18:325–330, 1998). Here we report experiments in which we used a retroviral shuttle vector system to introduce and characterize target loci in human chromosomes, and demonstrate that AAV vectors can correct several types of mutations with high fidelity, independent of chromosomal position. The gene targeting rates varied depending on the type of mutation being corrected, implicating cellular mismatch recognition functions in the reaction. Since AAV vectors can efficiently deliver DNA to many cell types both in vivo and ex vivo, our results suggest that AAV-mediated gene targeting will have wide applicability, including therapeutic gene correction.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    URL: Article
    DOI: 10.1128/JVI.73.9.7376-7380.1999
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1999
    detail.hit.zdb_id: 1495529-5
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  • 4
    Online Resource
    Online Resource
    Molecular Cloning and Characterization of the Genes Coding for the Highly Immunogenic Cluster of 90-Kilodalton Envelope Proteins from the Chlamydia psittaci Subtype That Causes Abortion in Sheep
    American Society for Microbiology ; 1998
    In:  Infection and Immunity Vol. 66, No. 4 ( 1998-04), p. 1317-1324
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 66, No. 4 ( 1998-04), p. 1317-1324
    Abstract: Proteins present in the outer membrane of chlamydiae that are involved in mucosal epithelial cell infection must clearly be identified and characterized if we are to understand and modify the pathogenic mechanisms utilized by these organisms. We have identified and isolated a family of four genes encoding putative outer membrane proteins (POMPs), a group of proteins of approximately 90 kDa present in the outer membrane of the subtype of Chlamydia psittaci that causes ovine enzootic abortion (strain S26/3). These proteins, although minor components, are major immunogens, as shown by the immunoblotting of chlamydial outer membrane complexes with postabortion sheep sera, and are therefore potential diagnostic and/or protective antigen candidates. Immunoblotting of the expressed amino- and carboxy-terminal halves of one of the POMPs with postabortion sheep sera showed that the major humoral immune response appeared to be directed solely against the amino-terminal half. This result, in combination with the positive immunofluorescence staining of S26/3-infected cells using POMP-specific (specific to the amino-terminal half of the proteins) monoclonal antibodies, suggests the probable surface localization of the POMPs and, more specifically, the surface exposure of the amino-terminal half of these proteins. The four pomp genes are highly homologous, sharing 82 to 100% similarity with each other (two of the genes are identical). Genes with strong and weak homologies were also detected in C. psittaci avian and feline pneumonitis strains, respectively. No pomp homologs were found in strains of C. trachomatis and C. pneumoniae , but this does not preclude their existence. The absence of homology with various subtypes of C. pecorum , which complicate the diagnosis of the ovine abortion subtype, indicates the possible suitability of the these 90-kDa proteins as serodiagnostic antigens.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.66.4.1317-1324.1998
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1998
    detail.hit.zdb_id: 1483247-1
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  • 5
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    Online Resource
    Comparison of Escherichia coli Strains Recovered from Human Cystitis and Pyelonephritis Infections in Transurethrally Challenged Mice
    American Society for Microbiology ; 1998
    In:  Infection and Immunity Vol. 66, No. 7 ( 1998-07), p. 3059-3065
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 66, No. 7 ( 1998-07), p. 3059-3065
    Abstract: Urinary tract infection, most frequently caused by Escherichia coli , is one of the most common bacterial infections in humans. A vast amount of literature regarding the mechanisms through which E. coli induces pyelonephritis has accumulated. Although cystitis accounts for 95% of visits to physicians for symptoms of urinary tract infections, few in vivo studies have investigated possible differences between E. coli recovered from patients with clinical symptoms of cystitis and that from patients with symptoms of pyelonephritis. Epidemiological studies indicate that cystitis-associated strains appear to differ from pyelonephritis-associated strains in elaboration of some putative virulence factors. With transurethrally challenged mice we studied possible differences using three each of the most virulent pyelonephritis and cystitis E. coli strains in our collection. The results indicate that cystitis strains colonize the bladder more rapidly than do pyelonephritis strains, while the rates of kidney colonization are similar. Cystitis strains colonize the bladder in higher numbers, induce more pronounced histologic changes in the bladder, and are more rapidly eliminated from the mouse urinary tract than pyelonephritis strains. These results provide evidence that cystitis strains differ from pyelonephritis strains in this model, that this model is useful for the study of the uropathogenicity of cystitis strains, and that it would be unwise to use pyelonephritis strains to study putative virulence factors important in the development of cystitis.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.66.7.3059-3065.1998
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1998
    detail.hit.zdb_id: 1483247-1
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  • 6
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    Online Resource
    Molecular Epidemiologic Evaluation of Transmissibility and Virulence of Mycobacterium tuberculosis
    American Society for Microbiology ; 1999
    In:  Journal of Clinical Microbiology Vol. 37, No. 6 ( 1999-06), p. 1764-1770
    Details
    In: Journal of Clinical Microbiology, American Society for Microbiology, Vol. 37, No. 6 ( 1999-06), p. 1764-1770
    Abstract: Discovery of genotypic markers associated with increased transmissibility in Mycobacterium tuberculosis would represent an important step in advancing mycobacterial virulence studies. M. tuberculosis strains may be classified into one of three genotypes on the basis of the presence of specific nucleotide substitutions in codon 463 of the katG gene ( katG -463) and codon 95 of the gyrA gene ( gyrA -95). It has previously been reported that two of these three genotypes are associated with increased IS 6110 -based clustering, a potential proxy of virulence. We designed a case-control analysis of U.S.-born patients with tuberculosis in San Francisco, Calif., between 1991 and 1997 to investigate associations between katG -463 and gyrA -95 genotypes and epidemiologically determined measures of strain-specific infectivity and pathogenicity and IS 6110 -based clustering status. We used a new class of molecular probes called molecular beacons to genotype the isolates rapidly. Infectivity was defined as the propensity of isolates to cause tuberculin skin test conversions among named contacts, and pathogenicity was defined as their propensity to cause active disease among named contacts. The molecular beacon assay was a simple and reproducible method for the detection of known single nucleotide polymorphisms in large numbers of clinical M. tuberculosis isolates. The results showed that no genotype of the katG -463- and gyrA -95-based classification system was associated with increased infectivity and pathogenicity or with increased IS 6110 -based clustering in San Francisco during the study period. We speculate that molecular epidemiologic studies investigating clinically relevant outcomes may contribute to the knowledge of the significance of laboratory-derived virulence factors in the propagation of tuberculosis in human communities.
    Type of Medium: Online Resource
    ISSN: 0095-1137 , 1098-660X
    URL: Article
    DOI: 10.1128/JCM.37.6.1764-1770.1999
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1999
    detail.hit.zdb_id: 1498353-9
    SSG: 12
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  • 7
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    Online Resource
    Packaging Cells Based on Inducible Gene Amplification for the Production of Adeno-Associated Virus Vectors
    American Society for Microbiology ; 1998
    In:  Journal of Virology Vol. 72, No. 9 ( 1998-09), p. 7024-7031
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 72, No. 9 ( 1998-09), p. 7024-7031
    Abstract: Although vectors based on adeno-associated virus (AAV) offer several unique advantages, their usage has been hampered by the difficulties encountered in vector production. In this report, we describe a new AAV packaging system based on inducible amplification of integrated helper and vector constructs containing the simian virus 40 (SV40) replication origin. The packaging and producer cell lines developed express SV40 T antigen under the control of the reverse tetracycline transactivator system, which allows inducible amplification of chromosomal loci linked to the SV40 origin. Culturing these cells in the presence of doxycycline followed by adenovirus infection resulted in helper and vector gene amplification as well as higher vector titers. Clonal producer cell lines generated vector titers that were 10 times higher than those obtained by standard methods, with approximately 10 4 vector particles produced per cell. These stocks were free of detectable replication-competent virus. The lack of a transfection step combined with the reproducibility of stable producer lines makes this packaging method ideally suited for the large-scale production of vector stocks for human gene therapy.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    URL: Article
    DOI: 10.1128/JVI.72.9.7024-7031.1998
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1998
    detail.hit.zdb_id: 1495529-5
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  • 8
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    Online Resource
    The Role of Interferon in Influenza Virus Tissue Tropism
    American Society for Microbiology ; 1998
    In:  Journal of Virology Vol. 72, No. 11 ( 1998-11-01), p. 8550-8558
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 72, No. 11 ( 1998-11-01), p. 8550-8558
    Abstract: We have studied the pathogenesis of influenza virus infection in mice that are unable to respond to type I or II interferons due to a targeted disruption of the STAT1 gene. STAT1−/− animals are 100-fold more sensitive to lethal infection with influenza A/WSN/33 virus than are their wild-type (WT) counterparts. Virus replicated only in the lungs of WT animals following intranasal (i.n.) virus inoculation, while STAT1−/− mice developed a fulminant systemic influenza virus infection following either i.n. or intraperitoneal inoculation. We investigated the mechanism underlying this altered virus tropism by comparing levels of virus replication in fibroblast cell lines and murine embryonic fibroblasts derived from WT mice, STAT−/− mice, and mice lacking gamma interferon (IFNγ−/− mice) or the IFN-α receptor (IFNαR−/− mice). Influenza A/WSN/33 virus replicates to high titers in STAT1−/− or IFNαR−/− fibroblasts, while cells derived from WT or IFNγ−/− animals are resistant to influenza virus infection. Immunofluorescence studies using WT fibroblast cell lines demonstrated that only a small subpopulation of WT cells can be infected and that in the few infected WT cells, virus replication is aborted at an early, nuclear phase. In all organs examined except the lung, influenza A WSN/33 virus infection is apparently prevented by an intact type I interferon response. Our results demonstrate that type I interferon plays an important role in determining the pathogenicity and tissue restriction of influenza A/WSN/33 virus in vivo and in vitro.
    Type of Medium: Online Resource
    ISSN: 1098-5514 , 0022-538X
    URL: Article
    DOI: 10.1128/JVI.72.11.8550-8558.1998
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1998
    detail.hit.zdb_id: 1495529-5
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  • 9
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    Immune Response to Yersinia Outer Proteins and Other Yersinia pestis Antigens after Experimental Plague Infection in Mice
    American Society for Microbiology ; 1999
    In:  Infection and Immunity Vol. 67, No. 4 ( 1999-04), p. 1922-1928
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 67, No. 4 ( 1999-04), p. 1922-1928
    Abstract: There is limited information concerning the nature and extent of the immune response to the virulence determinants of Yersinia pestis during the course of plague infection. In this study, we evaluated the humoral immune response of mice that survived lethal Y. pestis aerosol challenge after antibiotic treatment. Such a model may replicate the clinical situation in humans and indicate which virulence determinants are expressed in vivo. Immunoglobulin G enzyme-linked immunosorbent assay and immunoblotting were performed by using purified, recombinant antigens including F1, V antigen, YpkA, YopH, YopM, YopB, YopD, YopN, YopE, YopK, plasminogen activator protease (Pla), and pH 6 antigen as well as purified lipopolysaccharide. The major antigens recognized by murine convalescent sera were F1, V antigen, YopH, YopM, YopD, and Pla. Early treatment with antibiotics tended to reduce the immune response and differences between antibiotic treatment regimens were noted. These results may indicate that only some virulence factors are expressed and/or immunogenic during infection. This information may prove useful for selecting potential vaccine candidates and for developing improved serologic diagnostic assays.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.67.4.1922-1928.1999
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1999
    detail.hit.zdb_id: 1483247-1
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  • 10
    Online Resource
    Online Resource
    Immune Response to Yersinia Outer Proteins and Other Yersinia pestis Antigens after Experimental Plague Infection in Mice
    American Society for Microbiology ; 1999
    In:  Infection and Immunity Vol. 67, No. 4 ( 1999), p. 1922-1928
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 67, No. 4 ( 1999), p. 1922-1928
    Type of Medium: Online Resource
    ISSN: 1098-5522 , 0019-9567
    URL: Article
    DOI: 10.1128/.67.4.1922-1928.1999
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1999
    detail.hit.zdb_id: 1483247-1
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