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  • American Society for Microbiology  (12)
  • 2010-2014  (12)
  • 1
    In: Clinical and Vaccine Immunology, American Society for Microbiology, Vol. 21, No. 10 ( 2014-10), p. 1385-1395
    Abstract: Live attenuated nonpathogenic Mycobacterium bovis bacillus Calmette-Guérin (BCG) mediates long-lasting immune responses, has been safely administered as a tuberculosis vaccine to billions of humans, and is affordable to produce as a vaccine vector. These characteristics make it very attractive as a human immunodeficiency virus (HIV) vaccine vector candidate. Here, we assessed the immunogenicity of recombinant BCG (rBCG) constructs with different simian immunodeficiency virus (SIV) gag expression cassettes as priming agents followed by a recombinant replication-incompetent New York vaccinia virus (NYVAC) boost in rhesus macaques. Unmutated rBCG constructs were used in comparison to mutants with gene deletions identified in an in vitro screen for augmented immunogenicity. We demonstrated that BCG-SIV gag is able to elicit robust transgene-specific priming responses, resulting in strong SIV epitope-specific cellular immune responses. While enhanced immunogenicity was sustained at moderate levels for 〉 1 year following the heterologous boost vaccination, we were unable to demonstrate a protective effect after repeated rectal mucosal challenges with pathogenic SIVmac251. Our findings highlight the potential for rBCG vaccines to stimulate effective cross-priming and enhanced major histocompatibility complex class I presentation, suggesting that combining this approach with other immunogens may contribute to the development of effective vaccine regimens against HIV.
    Type of Medium: Online Resource
    ISSN: 1556-6811 , 1556-679X
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2014
    detail.hit.zdb_id: 1496863-0
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  • 2
    In: Infection and Immunity, American Society for Microbiology, Vol. 82, No. 12 ( 2014-12), p. 5317-5326
    Abstract: Mycobacteria, the etiological agents of tuberculosis and leprosy, have coevolved with mammals for millions of years and have numerous ways of suppressing their host's immune response. It has been suggested that mycobacteria may contain genes that reduce the host's ability to elicit CD8 + T cell responses. We screened 3,290 mutant Mycobacterium bovis bacillus Calmette Guerin (BCG) strains to identify genes that decrease major histocompatibility complex (MHC) class I presentation of mycobacterium-encoded epitope peptides. Through our analysis, we identified 16 mutant BCG strains that generated increased transgene product-specific CD8 + T cell responses. The genes disrupted in these mutant strains had disparate predicted functions. Reconstruction of strains via targeted deletion of genes identified in the screen recapitulated the enhanced immunogenicity phenotype of the original mutant strains. When we introduced the simian immunodeficiency virus (SIV) gag gene into several of these novel BCG strains, we observed enhanced SIV Gag-specific CD8 + T cell responses in vivo . This study demonstrates that mycobacteria carry numerous genes that act to dampen CD8 + T cell responses and suggests that genetic modification of these genes may generate a novel group of recombinant BCG strains capable of serving as more effective and immunogenic vaccine vectors.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2014
    detail.hit.zdb_id: 1483247-1
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  • 3
    Online Resource
    Online Resource
    American Society for Microbiology ; 2012
    In:  Antimicrobial Agents and Chemotherapy Vol. 56, No. 8 ( 2012-08), p. 4123-4130
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 56, No. 8 ( 2012-08), p. 4123-4130
    Abstract: As members of the indigenous human microbiota found on several mucosal tissues, Methanobrevibacter smithii and Methanosphaera stadtmanae are exposed to the effects of antimicrobial peptides (AMPs) secreted by these epithelia. Although antimicrobial and molecular effects of AMPs on bacteria are well described, data for archaea are not available yet. Besides, it is not clear whether AMPs affect them as the archaeal cell envelope differs profoundly in terms of chemical composition and structure from that of bacteria. The effects of different synthetic AMPs on growth of M. smithii , M. stadtmanae , and Methanosarcina mazei were tested using a microtiter plate assay adapted to their anaerobic growth requirements. All three tested methanoarchaea were highly sensitive against derivatives of human cathelicidin, of porcine lysin, and a synthetic antilipopolysaccharide peptide (Lpep); however, sensitivities differed markedly among the methanoarchaeal strains. The potent AMP concentrations affecting growth were below 10 μM, whereas growth of Escherichia coli WBB01 was not affected at peptide concentrations up to 10 μM under the same anaerobic growth conditions. Atomic force microscopy and transmission electron microscopy revealed that the structural integrity of the methanoarchaeal cells is destroyed within 4 h after incubation with AMPs. The disruption of the cell envelope of M. smithii , M. stadtmanae , and M. mazei within a few minutes of exposure was verified by using LIVE/DEAD staining. Our results strongly suggest that the release of AMPs by eukaryotic epithelial cells is a potent defense mechanism targeting not only bacteria, but also methanoarchaea.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2012
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
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  • 4
    Online Resource
    Online Resource
    American Society for Microbiology ; 2011
    In:  Applied and Environmental Microbiology Vol. 77, No. 24 ( 2011-12-15), p. 8669-8675
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 77, No. 24 ( 2011-12-15), p. 8669-8675
    Abstract: In spite of the significant impact of biomethylation on the mobility and toxicity of metals and metalloids in the environment, little is known about the biological formation of these methylated metal(loid) compounds. While element-specific methyltransferases have been isolated for arsenic, the striking versatility of methanoarchaea to methylate numerous metal(loid)s, including rare elements like bismuth, is still not understood. Here, we demonstrate that the same metal(loid)s (arsenic, selenium, antimony, tellurium, and bismuth) that are methylated by Methanosarcina mazei in vivo are also methylated by in vitro assays with purified recombinant MtaA, a methyltransferase catalyzing the methyl transfer from methylcobalamin [CH 3 Cob(III)] to 2-mercaptoethanesulfonic acid (CoM) in methylotrophic methanogenesis. Detailed studies revealed that cob(I)alamin [Cob(I)] , formed by MtaA-catalyzed demethylation of CH 3 Cob(III), is the causative agent for the multimetal(loid) methylation observed. Moreover, Cob(I) is also capable of metal(loid) hydride generation. Global transcriptome profiling of M. mazei cultures exposed to bismuth did not reveal induced methyltransferase systems but upregulated regeneration of methanogenic cofactors in the presence of bismuth. Thus, we conclude that the multimetal(loid) methylation in vivo is attributed to side reactions of CH 3 Cob(III) with reduced cofactors formed in methanogenesis. The close connection between metal(loid) methylation and methanogenesis explains the general capability of methanoarchaea to methylate metal(loid)s.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2011
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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  • 5
    In: Journal of Virology, American Society for Microbiology, Vol. 87, No. 24 ( 2013-12-15), p. 13589-13597
    Abstract: Effective strategies are needed to block mucosal transmission of human immunodeficiency virus type 1 (HIV-1). Here, we address a crucial question in HIV-1 pathogenesis: whether infected donor mononuclear cells or cell-free virus plays the more important role in initiating mucosal infection by HIV-1. This distinction is critical, as effective strategies for blocking cell-free and cell-associated virus transmission may be different. We describe a novel ex vivo model system that utilizes sealed human colonic mucosa explants and demonstrate in both the ex vivo model and in vivo using the rectal challenge model in rhesus monkeys that HIV-1-infected lymphocytes can transmit infection across the mucosa more efficiently than cell-free virus. These findings may have significant implications for our understanding of the pathogenesis of mucosal transmission of HIV-1 and for the development of strategies to prevent HIV-1 transmission.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2013
    detail.hit.zdb_id: 1495529-5
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  • 6
    Online Resource
    Online Resource
    American Society for Microbiology ; 2010
    In:  Applied and Environmental Microbiology Vol. 76, No. 21 ( 2010-11), p. 7181-7187
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 76, No. 21 ( 2010-11), p. 7181-7187
    Abstract: Recent metagenomic sequencing studies of uncultured viral populations have provided novel insights into the ecology of environmental bacteriophage. At the same time, viral metagenomes could also represent a potential source of recombinant proteins with biotechnological value. In order to identify such proteins, a novel two-step screening technique was devised for cloning phage lytic enzymes from uncultured viral DNA. This plasmid-based approach first involves a primary screen in which transformed Escherichia coli clones that demonstrate colony lysis following exposure to inducing agent are identified. This effect, which can be due to the expression of membrane-permeabilizing phage holins, is discerned by the development a hemolytic effect in surrounding blood agar. In a secondary step, the clones identified in the primary screen are overlaid with autoclaved Gram-negative bacteria (specifically Pseudomonas aeruginosa ) to assay directly for recombinant expression of lytic enzymes, which are often encoded proximally to holins in phage genomes. As proof-of-principle, the method was applied to a viral metagenomic library constructed from mixed animal feces, and 26 actively expressed lytic enzymes were cloned. These proteins include both Gram-positive-like and Gram-negative-like enzymes, as well as several atypical lysins whose predicted structures are less common among known phage. Overall, this study represents one of the first functional screens of a viral metagenomic population, and it provides a general approach for characterizing lysins from uncultured phage.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2010
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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  • 7
    Online Resource
    Online Resource
    American Society for Microbiology ; 2013
    In:  Antimicrobial Agents and Chemotherapy Vol. 57, No. 6 ( 2013-06), p. 2743-2750
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 57, No. 6 ( 2013-06), p. 2743-2750
    Abstract: Methicillin-resistant Staphylococcus aureus (MRSA) and Streptococcus pyogenes (group A streptococcus [GrAS]) cause serious and sometimes fatal human diseases. They are among the many Gram-positive pathogens for which resistance to leading antibiotics has emerged. As a result, alternative therapies need to be developed to combat these pathogens. We have identified a novel bacteriophage lysin (PlySs2), derived from a Streptococcus suis phage, with broad lytic activity against MRSA, vancomycin-intermediate S. aureus (VISA), Streptococcus suis , Listeria , Staphylococcus simulans , Staphylococcus epidermidis , Streptococcus equi , Streptococcus agalactiae (group B streptococcus [GBS]), S. pyogenes , Streptococcus sanguinis , group G streptococci (GGS), group E streptococci (GES), and Streptococcus pneumoniae . PlySs2 has an N-terminal cysteine-histidine aminopeptidase (CHAP) catalytic domain and a C-terminal SH3b binding domain. It is stable at 50°C for 30 min, 37°C for 〉 24 h, 4°C for 15 days, and −80°C for 〉 7 months; it maintained full activity after 10 freeze-thaw cycles. PlySs2 at 128 μg/ml in vitro reduced MRSA and S. pyogenes growth by 5 logs and 3 logs within 1 h, respectively, and exhibited a MIC of 16 μg/ml for MRSA. A single, 2-mg dose of PlySs2 protected 92% (22/24) of the mice in a bacteremia model of mixed MRSA and S. pyogenes infection. Serially increasing exposure of MRSA and S. pyogenes to PlySs2 or mupirocin resulted in no observed resistance to PlySs2 and resistance to mupirocin. To date, no other lysin has shown such notable broad lytic activity, stability, and efficacy against multiple, leading, human bacterial pathogens; as such, PlySs2 has all the characteristics to be an effective therapeutic.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2013
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
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  • 8
    In: mBio, American Society for Microbiology, Vol. 3, No. 1 ( 2012-03)
    Abstract: Many Gram-negative pathogens utilize type 3 secretion systems to deliver tens of effectors into host cells. In order to understand the diverse ways that these organisms cause disease, it is necessary to identify their effectors, many of which require chaperones to be secreted. Here we establish that class IB chaperones are not promiscuous, as previously proposed, but rather recognize a conserved effector sequence. We demonstrate that pattern search algorithms based on this defined sequence can be used to identify previously unknown effectors. Furthermore, we observe that class IB chaperones from at least seven bacterial species are functionally interchangeable. Not only do they bind and mediate the delivery of their own set of effectors into host cells but they also bind to type 3 substrates from other bacteria, suggesting that inhibitors that block chaperone-effector interactions could provide a novel means to effectively treat infections due to Gram-negative pathogens, including organisms resistant to currently available antibiotics.
    Type of Medium: Online Resource
    ISSN: 2161-2129 , 2150-7511
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2012
    detail.hit.zdb_id: 2557172-2
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  • 9
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 55, No. 9 ( 2011-09), p. 4196-4203
    Abstract: GS-9190 (Tegobuvir) is a novel imidazopyridine inhibitor of hepatitis C virus (HCV) RNA replication in vitro and has demonstrated potent antiviral activity in patients chronically infected with genotype 1 (GT1) HCV. GS-9190 exhibits reduced activity against GT2a (JFH1) subgenomic replicons and GT2a (J6/JFH1) infectious virus, suggesting that the compound's mechanism of action involves a genotype-specific viral component. To further investigate the GS-9190 mechanism of action, we utilized the susceptibility differences between GT1b and GT2a by constructing a series of replicon chimeras where combinations of 1b and 2a nonstructural proteins were encoded within the same replicon. The antiviral activities of GS-9190 against the chimeric replicons were reduced to levels comparable to that of the wild-type GT2a replicon in chimeras expressing GT2a NS5B. GT1b replicons in which the β-hairpin region (amino acids 435 to 455) was replaced by the corresponding sequence of GT2a were markedly less susceptible to GS-9190, indicating the importance of the thumb subdomain of the polymerase in this effect. Resistance selection in GT1b replicon cells identified several mutations in NS5B (C316Y, Y448H, Y452H, and C445F) that contributed to the drug resistance phenotype. Reintroduction of these mutations into wild-type replicons conferred resistance to GS-9190, with the number of NS5B mutations correlating with the degree of resistance. Analysis of GS-9190 cross-resistance against previously reported NS5B drug-selected mutations showed that the resistance pattern of GS-9190 is different from other nonnucleoside inhibitors. Collectively, these data demonstrate that GS-9190 represents a novel class of nonnucleoside polymerase inhibitors that interact with NS5B likely through involvement of the β-hairpin in the thumb subdomain.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2011
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
    Library Location Call Number Volume/Issue/Year Availability
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  • 10
    Online Resource
    Online Resource
    American Society for Microbiology ; 2013
    In:  mBio Vol. 4, No. 1 ( 2013-03)
    In: mBio, American Society for Microbiology, Vol. 4, No. 1 ( 2013-03)
    Abstract: External stresses that disrupt metabolic components can perturb cellular functions and affect growth. A similar consequence is expected if endogenously generated metabolites are reactive and persist in the cellular environment. Here we show that the metabolic intermediate 2-aminoacrylate (2AA) causes significant cellular damage if allowed to accumulate aberrantly. Furthermore, we show that the widely conserved protein RidA prevents this accumulation by facilitating conversion of 2AA to a stable metabolite. This work demonstrates that the reactive metabolite 2AA, previously considered innocuous in the cell due to a short half-life in aqueous solution, can survive in the cellular environment long enough to cause damage. This work provides insights into the roles and persistence of reactive metabolites in vivo and shows that the RidA family of proteins is able to prevent damage caused by a reactive intermediate that is created as a consequence of PLP-dependent chemistry.
    Type of Medium: Online Resource
    ISSN: 2161-2129 , 2150-7511
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2013
    detail.hit.zdb_id: 2557172-2
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