Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1
    In: Nature Chemical Biology, Springer Science and Business Media LLC, Vol. 11, No. 9 ( 2015-9), p. 625-631
    Type of Medium: Online Resource
    ISSN: 1552-4450 , 1552-4469
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2015
    detail.hit.zdb_id: 2190276-8
    SSG: 12
    SSG: 15,3
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    In: mBio, American Society for Microbiology, Vol. 8, No. 4 ( 2017-09-06)
    Abstract: The human pathogen Shigella flexneri causes bacterial dysentery by invading colonic epithelial cells, rapidly multiplying within their cytoplasm, and then spreading intercellularly to neighboring cells. Worldwide, Shigella spp. infect hundreds of millions of people annually, with fatality rates up to 15%. Antibiotic treatment of Shigella infections is compromised by increasing antibiotic resistance, and there is no approved vaccine to prevent future infections. This has created a growing need to understand Shigella pathogenesis and identify new targets for antimicrobial therapeutics. Here we show a previously unknown role of phospholipids in S. flexneri pathogenesis. We demonstrate that cardiolipin is required in the outer membrane for proper surface localization of IcsA and in the inner membrane for cell division during growth in the host cell cytoplasm.
    Type of Medium: Online Resource
    ISSN: 2161-2129 , 2150-7511
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2017
    detail.hit.zdb_id: 2557172-2
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    In: Infection and Immunity, American Society for Microbiology, Vol. 86, No. 3 ( 2018-03)
    Abstract: Francisella tularensis is a Gram-negative, facultative, intracellular coccobacillus that can infect a wide variety of hosts. In humans, F. tularensis causes the zoonosis tularemia following insect bites, ingestion, inhalation, and the handling of infected animals. The fact that a very small inoculum delivered by the aerosol route can cause severe disease, coupled with the possibility of its use as an aerosolized bioweapon, has led to the classification of Francisella tularensis as a category A select agent and has renewed interest in the formulation of a vaccine. To this end, we engineered a type A strain SchuS4 derivative containing a targeted deletion of the major facilitator superfamily (MFS) transporter fptB . Based on the attenuating capacity of this deletion in the F. tularensis LVS background, we hypothesized that the deletion of this transporter would alter the intracellular replication and cytokine induction of the type A strain and attenuate virulence in the stringent C57BL/6J mouse model. Here we demonstrate that the deletion of fptB significantly alters the intracellular life cycle of F. tularensis , attenuating intracellular replication in both cell line-derived and primary macrophages and inducing a novel cytosolic escape delay. Additionally, we observed prominent differences in the in vitro cytokine profiles in human macrophage-like cells. The mutant was highly attenuated in the C57BL/6J mouse model and provided partial protection against virulent type A F. tularensis challenge. These results indicate a fundamental necessity for this nutrient transporter in the timely progression of F. tularensis through its replication cycle and in pathogenesis.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 1483247-1
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    In: Infection and Immunity, American Society for Microbiology, Vol. 87, No. 7 ( 2019-07)
    Abstract: Haemophilus ducreyi causes chancroid and is a major cause of cutaneous ulcers in children. Due to environmental reservoirs, both class I and class II H. ducreyi strains persist in cutaneous ulcer regions of endemicity following mass drug administration of azithromycin, suggesting the need for a vaccine. The hemoglobin receptor (HgbA) is a leading vaccine candidate, but its efficacy in animal models is class specific. Controlled human infection models can be used to evaluate vaccines, but only a class I strain (35000HP) has been characterized in this model. As a prelude to evaluating HgbA vaccines in the human model, we tested here whether a derivative of 35000HP containing a class II hgbA allele (FX548) is as virulent as 35000HP in humans. In eight volunteers infected at three sites with each strain, the papule formation rate was 95.8% for 35000HP versus 62.5% for FX548 ( P  = 0.021). Excluding doses of FX548 that were ≥2-fold higher than those of 35000HP, the pustule formation rate was 25% for 35000HP versus 11.7% for FX548 ( P  = 0.0053). By Western blot analysis, FX548 and 35000HP expressed equivalent amounts of HgbA in whole-cell lysates and outer membranes. The growth of FX548 and 35000HP was similar in media containing hemoglobin or hemin. By whole-genome sequencing and single-nucleotide polymorphism analysis, FX548 contained no mutations in open reading frames other than hgbA . We conclude that by an unknown mechanism, FX548 is partially attenuated in humans and is not a suitable strain for HgbA vaccine efficacy trials in the model.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2019
    detail.hit.zdb_id: 1483247-1
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    In: Infection and Immunity, American Society for Microbiology, Vol. 85, No. 6 ( 2017-06)
    Abstract: Mycoplasma gallisepticum , known primarily as a respiratory pathogen of domestic poultry, has emerged since 1994 as a significant pathogen of the house finch ( Haemorhous mexicanus ) causing severe conjunctivitis and mortality. House finch-associated M. gallisepticum (HFMG) spread rapidly and increased in virulence for the finch host in the eastern United States. In the current study, we assessed virulence in domestic poultry with two temporally distant, and yet geographically consistent, HFMG isolates which differ in virulence for house finches—Virginia 1994 (VA1994), the index isolate of the epidemic, and Virginia 2013 (VA2013), a recent isolate of increased house finch virulence. Here we report a significant difference between VA1994 and VA2013 in their levels of virulence for chickens; notably, this difference correlated inversely to the difference in their levels of virulence for house finches. VA1994, while moderately virulent in house finches, displayed significant virulence in the chicken respiratory tract. VA2013, while highly virulent in the house finch, was significantly attenuated in chickens relative to VA1994, displaying less-severe pathological lesions in, and reduced bacterial recovery from, the respiratory tract. Overall, these data indicate that a recent isolate of HFMG is greatly attenuated in the chicken host relative to the index isolate, notably demonstrating a virulence phenotype in chickens inversely related to that in the finch host.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2017
    detail.hit.zdb_id: 1483247-1
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    In: Infection and Immunity, American Society for Microbiology, Vol. 86, No. 10 ( 2018-10)
    Abstract: Proteus mirabilis is a leading cause of catheter-associated urinary tract infections (CAUTIs) and urolithiasis. The transcriptional regulator MrpJ inversely modulates two critical aspects of P. mirabilis UTI progression: fimbria-mediated attachment and flagellum-mediated motility. Transcriptome data indicated a network of virulence-associated genes under MrpJ's control. Here, we identify the direct gene regulon of MrpJ and its contribution to P. mirabilis pathogenesis, leading to the discovery of novel virulence targets. Ch romatin i mmuno p recipitation followed by high-throughput seq uencing (ChIP-seq) was used for the first time in a CAUTI pathogen to probe for in vivo direct targets of MrpJ. Selected MrpJ-regulated genes were mutated and assessed for their contribution to UTI using a mouse model. ChIP-seq revealed a palindromic MrpJ binding sequence and 78 MrpJ-bound regions, including binding sites upstream of genes involved in motility, fimbriae, and a type VI secretion system (T6SS). A combinatorial mutation approach established the contribution of three fimbriae ( fim8A , fim14A , and pmpA ) to UTI and a new pathogenic role for the T6SS in UTI progression. In conclusion, this study (i) establishes the direct gene regulon and an MrpJ consensus binding site and (ii) led to the discovery of new virulence genes in P. mirabilis UTI, which could be targeted for therapeutic intervention of CAUTI.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 1483247-1
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Online Resource
    Online Resource
    American Society for Microbiology ; 2018
    In:  Infection and Immunity Vol. 86, No. 11 ( 2018-11)
    In: Infection and Immunity, American Society for Microbiology, Vol. 86, No. 11 ( 2018-11)
    Abstract: Enterotoxigenic Escherichia coli (ETEC), a heterogeneous diarrheal pathovar defined by production of heat-labile (LT) and/or heat-stable (ST) toxins, causes substantial morbidity among young children in the developing world. Studies demonstrating a major burden of ST-producing ETEC have focused interest on ST toxoids for ETEC vaccines. We examined fundamental aspects of ST biology using ETEC strain H10407, which carries estH and estP genes encoding STh and STp, respectively, in addition to eltAB genes responsible for LT. Here, we found that deletion of estH significantly diminished cyclic GMP (cGMP) activation in target epithelia, while deletion of estP had a surprisingly modest impact, and a dual estH estP mutant was not appreciably different from the estH mutant. However, we noted that either STh or STp recombinant peptides stimulated cGMP production and that the loss of estP was compensated by enhanced estH transcription. We also found that the TolC efflux protein was essential for toxin secretion and delivery, providing a potential avenue for efflux inhibitors in treatment of acute diarrheal illness. In addition, we demonstrated that the EtpA adhesin is required for optimal delivery of ST and that antibodies against either the adhesin or STh significantly impaired toxin delivery and cGMP activation in target T84 cells. Finally, we used FLAG epitope fusions to demonstrate that the STh propeptide sequence is secreted by ETEC, potentially providing additional epitopes for antibody neutralization. These studies collectively extend our understanding of ETEC pathogenesis and potentially inform additional avenues to mitigate disease by these common diarrheal pathogens.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 1483247-1
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    In: Infection and Immunity, American Society for Microbiology, Vol. 87, No. 3 ( 2019-03)
    Abstract: Animal models have played a key role in providing an understanding of the mechanisms that govern the pathophysiology of intestinal diseases. To expand on the repertoire of organisms available to study enteric diseases, we report on the use of the Drosophila melanogaster model to identify a novel function of an effector protein secreted by Vibrio parahaemolyticus , which is an enteric pathogen found in contaminated seafood. During pathogenesis, V. parahaemolyticus secretes effector proteins that usurp the host’s innate immune signaling pathways, thus allowing the bacterium to evade detection by the innate immune system. One secreted effector protein, VopA, has potent inhibitory effects on mitogen-activated protein kinase (MAPK) signaling pathways via the acetylation of critical residues within the catalytic loops of mitogen-activated protein kinase kinases (MAPKKs). Using the Drosophila model and cultured mammalian cells, we show that VopA also has potent modulating activity on focal adhesion complex (FAC) proteins, where VopA markedly reduced the levels of focal adhesion kinase (FAK) phosphorylation at Ser910, whereas the phosphorylation levels of FAK at Tyr397 and Tyr861 were markedly increased. Cultured cells expressing VopA were also impaired in their ability to migrate and repopulate areas subjected to a scratch wound. Consistently, expression of VopA in Drosophila midgut enterocytes disrupted the normal enterocyte arrangement. Finally, VopA inhibited apoptosis in both Drosophila tissues and mammalian cultured cells. Together, our data show that VopA can alter normal intestinal homeostatic processes to facilitate opportunities for V. parahaemolyticus to prolong infection within the host.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2019
    detail.hit.zdb_id: 1483247-1
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    In: Infection and Immunity, American Society for Microbiology, Vol. 86, No. 3 ( 2018-03)
    Abstract: CpxRA is an envelope stress response system found in all members of the family Enterobacteriaceae ; CpxA has kinase activity for CpxR and phosphatase activity for phospho-CpxR, a transcription factor. CpxR also accepts phosphate groups from acetyl phosphate, a glucose metabolite. Activation of CpxR increases the transcription of genes encoding membrane repair and downregulates virulence determinants. We hypothesized that activation of CpxR could serve as an antimicrobial/antivirulence strategy and discovered compounds that activate CpxR in Escherichia coli by inhibiting CpxA phosphatase activity. As a prelude to testing such compounds in vivo , here we constructed cpxA (in the presence of glucose, CpxR is activated because of a lack of CpxA phosphatase) and cpxR (system absent) deletion mutants of uropathogenic E. coli (UPEC) CFT073. By RNA sequencing, few transcriptional differences were noted between the cpxR mutant and its parent, but in the cpxA mutant, several UPEC virulence determinants were downregulated, including the fim and pap operons, and it exhibited reduced mannose-sensitive hemagglutination of guinea pig red blood cells in vitro . In competition experiments with mice, both mutants were less fit than the parent in the urine, bladder, and kidney; these fitness defects were complemented in trans . Unexpectedly, in single-strain challenges, only the cpxA mutant was attenuated for virulence in the kidney but not in the bladder or urine. For the cpxA mutant, this may be due to the preferential use of amino acids over glucose as a carbon source in the bladder and urine by UPEC. These studies suggest that CpxA phosphatase inhibitors may have some utility for treating complex urinary tract infections.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 1483247-1
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    In: Infection and Immunity, American Society for Microbiology, Vol. 85, No. 10 ( 2017-10)
    Abstract: Mycoplasma gallisepticum , the primary etiologic agent of chronic respiratory disease (CRD) in poultry, leads to prolonged recruitment and activation of inflammatory cells in the respiratory mucosa. This is consistent with the current model of immune dysregulation that ostensibly allows the organism to evade clearance mechanisms and establish chronic infection. To date, studies using quantitative reverse transcription-PCR (qRT-PCR) and microarrays have shown a significant transient upregulation of cytokines and chemokines from tracheal epithelial cells (TECs) in vitro and tracheal tissue ex vivo in response to virulent strain R low that contributes to the infiltration of inflammatory cells into the tracheal mucosa. To expand upon these experiments, RNA was isolated from tracheas of 20 chickens infected with M. gallisepticum R low and 20 mock-infected animals at days 1, 3, 5, and 7 postinoculation, and samples were analyzed for differential gene expression using Illumina RNA sequencing. A rapid host response was observed 24 h postinfection, with over 2,500 significantly differentially expressed genes on day 3, the peak of infection. Many of these genes have immune-related functions involved in signaling pathways, including Toll-like receptor (TLR), mitogen-activated protein kinase, Jak-STAT, and the nucleotide oligomerization domain-like receptor pathways. Of interest was the increased expression of numerous cell surface receptors, including TLR4 and TLR15, which may contribute to the production of cytokines. Metabolic pathways were also activated on days 1 and 3 postinfection, ostensibly due to epithelial cell distress that occurs upon infection. Early perturbations in tissue-wide gene expression, as observed here, may underpin a profound immune dysregulation, setting the stage for disease manifestations characteristic of M. gallisepticum infection.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2017
    detail.hit.zdb_id: 1483247-1
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages