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  • American Society for Microbiology  (8)
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  • American Society for Microbiology  (8)
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  • 1
    Online Resource
    Online Resource
    Vascular Endothelial Growth Factor A Contributes to Increased Mammalian Respiratory Epithelial Permeability Induced by Pasteurella multocida Infection
    American Society for Microbiology ; 2023
    In:  Microbiology Spectrum Vol. 11, No. 2 ( 2023-04-13)
    Details
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 11, No. 2 ( 2023-04-13)
    Abstract: Pasteurella multocida infection can cause significant zoonotic respiratory problems in both humans and animals, but little is known about the mechanisms used by P. multocida to invade and cross the mammalian respiratory barrier. In this study, we investigated the influence of P. multocida infection on the dysfunction of the respiratory epithelial barrier. In vivo tests in mouse infection models demonstrated that P. multocida infection significantly increased epithelial permeability and increased the expression of vascular endothelial growth factor A (VEGFA) and endothelial nitric oxide synthase (eNOS) in murine tracheae and lungs. In murine lung epithelial cell (MLE-12) models, P. multocida infection decreased the expression of tight junctions (ZO-1) and adherens junctions (β-catenin and E-cadherin) proteins but induced the activation of hypoxia-inducible factor 1α (HIF-1α) and VEGFA signaling. When the expression of HIF-1α is suppressed, the induction of VEGFA and ZO-1 expression by P. multocida infection is decreased. We also found that intervention of HIF-1α and VEGFA signaling affected infection outcomes caused by respiratory bacteria in mouse models. Most importantly, we demonstrate that P. multocida infection increases the permeability of human respiratory epithelial cells and that this process is associated with the activation of HIF-1α and VEGFA signaling and likely contributes to the pathogenesis of P. multocida infection in humans. IMPORTANCE The mammalian respiratory epithelium forms the first line of defense against infections with P. multocida , an important zoonotic respiratory pathogen. In this study, we found that P. multocida infection increased respiratory epithelial permeability and promoted the induction of the HIF-1α–VEGFA axis in both mouse and murine cell models. Similar findings were also demonstrated in human respiratory epithelial cells. The results from this study provide important knowledge about the pathogenesis of P. multocida causing infections in both animals and humans.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    URL: Article
    DOI: 10.1128/spectrum.04554-22
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2023
    detail.hit.zdb_id: 2807133-5
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  • 2
    Online Resource
    Online Resource
    Identification of a KPC Variant Conferring Resistance to Ceftazidime-Avibactam from ST11 Carbapenem-Resistant Klebsiella pneumoniae Strains
    American Society for Microbiology ; 2022
    In:  Microbiology Spectrum Vol. 10, No. 2 ( 2022-04-27)
    Details
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 10, No. 2 ( 2022-04-27)
    Abstract: A novel Klebsiella pneumoniae carbapenemase (KPC) variant, KPC-93, was identified in two Klebsiella pneumoniae clinical isolates from a patient from China treated with ceftazidime-avibactam. KPC-93 possessed a five-amino-acids insertion (Pro-Asn-Asn-Arg-Ala) between Ambler positions 267 and 268 in KPC-2. Cloning and expression of the bla KPC-93 gene in Escherichia coli , followed by determination of minimum inhibitory concentration (MIC) values and kinetic parameters, showed that KPC-93 exhibited increased resistance to ceftazidime-avibactam, but a drastic decrease in carbapenemase activity. Our data highlight that a KPC variant conferring resistance to ceftazidime-avibactam could be easily induced by ceftazidime-avibactam treatment and that actions are required to control dissemination of these determinants. IMPORTANCE Ceftazidime-avibactam (CZA) is a novel β-lactam/β-lactamase inhibitor combination with activity against serine β-lactamases, including the Ambler class A enzyme KPC. However, during recent years, there have been increasing reports of emergence of new KPC variants that could confer resistance to CZA. This has limited its clinical application. Here, we reported a new KPC variant, KPC-93, that could confer CZA resistance. KPC-93 possessed a five-amino-acids insertion (Pro-Asn-Asn-Arg-Ala) between Ambler positions 267 and 268 in KPC-2. Our findings have revealed the potential risk of bla KPC gene mutations associated with CZA exposure over a short period of time.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    URL: Article
    DOI: 10.1128/spectrum.02655-21
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2022
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  • 3
    Online Resource
    Online Resource
    Survival Characteristics and Transcriptomic Analyses Reveal the Adaptive Response of the Aquatic Pathogen Non-O1/O139 Vibrio cholerae to Starvation Stress
    American Society for Microbiology ; 2022
    In:  Microbiology Spectrum Vol. 10, No. 3 ( 2022-06-29)
    Details
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 10, No. 3 ( 2022-06-29)
    Abstract: Non-O1/O139 Vibrio cholerae is a pathogen of various aquatic organisms but requires major self-regulation to overcome environmental stress in the aquatic environment. However, its survival strategies under environmental stress are not well understood. The objective of this study was to describe the survival characteristics and changes in expression of stress resistance-related genes of non-O1/O139 V. cholerae after 6 months of starvation at room temperature. The results demonstrated that starved cells were still viable, exhibited shortened rods and shrinking surface, and maintained virulence to Macrobrachium rosenbergii . To investigate the changes in gene expression in non-O1/O139 V. cholerae under starvation stress, especially those involved in stress resistance, transcriptome profiles of starved and wild-type cells were determined. The differentially expressed genes (DEGs) in starved cells were identified, including 191 upregulated genes and 180 downregulated genes. Among these DEGs, the well-known stress resistance-related genes were upregulated significantly, including rpoS , rpoD , rpoN , rpoE , uspA , uspC , cspD , hslJ , etc. Gene Ontology (GO) analysis of the DEGs demonstrated that environmental adaptation-related categories, such as response to stimulus and signal transduction, were upregulated significantly in the starved cells, while cell motility was downregulated significantly. These DEGs were also enriched into 54 KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways, including biofilm formation, two-component system, quorum sensing, flagellar assembly, bacterial chemotaxis stress resistance-related pathways, etc. The potential existence of long-starved non-O1/O139 V. cholerae bacteria in the aquatic environment may raise new concerns about this devastating pathogen in aquaculture. IMPORTANCE Non-O1/O139 V. cholerae is a causal agent of vibriosis that can be subject to nutrient insufficiency and cause high rates of mortality in aquatic animals. However, its molecular mechanisms of survival in response to starvation stress have been investigated only partially. Here, we demonstrate that under starvation stress, non-O1/O139 V. cholerae can survive over the long term and cause disease by dwarfing of the cell structure, upregulation of a series of stress resistance-related genes, and downregulation of flagellum assembly-related genes. This knowledge can help the development of intervention strategies to control non-O1/O139 V. cholerae infection in aquaculture.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    URL: Article
    DOI: 10.1128/spectrum.01939-21
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2022
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  • 4
    Online Resource
    Online Resource
    Arsenic trioxide-induced apoptosis contributes to suppression of viral reservoir in SIV-infected rhesus macaques
    American Society for Microbiology ; 2023
    In:  Microbiology Spectrum
    Details
    In: Microbiology Spectrum, American Society for Microbiology
    Abstract: Although antiretroviral therapy (ART) can effectively suppress the viral load of AIDS patients, it cannot functionally cure HIV infection due to the existence of HIV reservoir. Strategies toward HIV functional cure are still highly anticipated to ultimately end the pandemic of AIDS. Herein, we investigated the direct role of As 2 O 3 independent of ART in chronically SIV-infected macaques and explored the underlying mechanisms of the potential of As 2 O 3 in the treatment of HIV/SIV infection. Meanwhile, we investigated the therapeutic effects of ART+As 2 O 3 in acutely SIVmac239-infected macaques. This study showed that As 2 O 3 has the potential to be launched into the “shock-and-kill” strategy to suppress HIV/SIV reservoir due to its latency-reversing and apoptosis-inducing properties.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    URL: Article
    DOI: 10.1128/spectrum.00525-23
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2023
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  • 5
    Online Resource
    Online Resource
    Emergence and Expansion of a Carbapenem-Resistant Pseudomonas aeruginosa Clone Are Associated with Plasmid-Borne bla KPC-2 and Virulence-Related Genes
    American Society for Microbiology ; 2021
    In:  mSystems Vol. 6, No. 3 ( 2021-06-29)
    Details
    In: mSystems, American Society for Microbiology, Vol. 6, No. 3 ( 2021-06-29)
    Abstract: Pseudomonas aeruginosa is a major opportunistic pathogen and one of the leading bacterial species causing health care-associated infections. Carbapenems are the most effective antimicrobial agents for the treatment of severe infections caused by P. aeruginosa . However, our recent surveillance demonstrated that the prevalence of carbapenem-resistant P. aeruginosa (CRPA) reached 38.67% in Zhejiang, China. By analyzing CRPA isolates collected from patients from 2006 to 2018, we found that 33% of CRPA isolates carried the gene bla KPC-2 , which conferred high-level resistance to carbapenems and other β-lactams. In particular, a CRPA clone, ST463 (sequence type 463), emerged and has become the predominant CRPA clone among the population. Genome sequencing demonstrated that ST463 expansion was associated with plasmid-borne bla KPC-2 . The mobile element flanking bla KPC-2 , the type IV secretion system, and the successful expansion of clone ST463 might have further favored bla KPC-2 spread in P. aeruginosa . Molecular clock analysis dated the emergence of clone ST463 to around 2007. Genome-wide association analysis showed that 567 genes were associated with clone ST463, including several known virulence genes related to the biosynthesis of lipooligosaccharide (LOS) O-antigens and exotoxin. These findings indicate that ST463 is expanding with plasmid-borne bla KPC-2 and virulence-related genes in nosocomial infections, and close surveillance should be undertaken in the future. IMPORTANCE Health care-associated infections, also known as nosocomial infections, are the most frequent adverse events in health care delivery worldwide, causing high rates of morbidity and mortality and high health care costs. Pseudomonas aeruginosa is one of the leading bacterial species causing health care-associated infections. Carbapenems are the most effective antimicrobial agents for the treatment of its severe infections. However, the prevalence of carbapenem-resistant P. aeruginosa (CRPA) has been increasing rapidly in recent years, and our surveillance demonstrated that the prevalence of CRPA reached 38.67% in Zhejiang, China. Genome sequencing of CRPA isolates over a decade showed that a CRPA clone (ST463) emerged recently. The clone is highly resistant to β-lactams, including carbapenems, and fluoroquinolones. Genome-wide association analysis showed that the clone expanded with virulence-related genes and the plasmid-borne carbapenem-resistant gene bla KPC-2 . These findings are of significant public health importance, as the information will facilitate the control and minimization of CRPA nosocomial infections.
    Type of Medium: Online Resource
    ISSN: 2379-5077
    URL: Article
    DOI: 10.1128/mSystems.00154-21
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2021
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  • 6
    Online Resource
    Online Resource
    Exacerbated AIDS Progression by PD-1 Blockade during Therapeutic Vaccination in Chronically Simian Immunodeficiency Virus-Infected Rhesus Macaques after Interruption of Antiretroviral Therapy
    American Society for Microbiology ; 2022
    In:  Journal of Virology Vol. 96, No. 3 ( 2022-02-09)
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 96, No. 3 ( 2022-02-09)
    Abstract: The persistence of cells latently infected with HIV-1, named the latent reservoir, is the major barrier to HIV-1 eradication, and the formation and maintenance of the latent reservoir might be exacerbated by activation of the immunoinhibitory pathway and dysfunction of CD8 + T cells during HIV-1 infection. Our previous findings demonstrated that prophylactic vaccination combined with PD-1 blockade generated distinct immune response profiles and conferred effective control of highly pathogenic SIV mac239 infection in rhesus macaques. However, to our surprise, herein we found that a therapeutic vaccination in combination with PD-1 blockade resulted in activation of the viral reservoir, faster viral rebound after treatment interruption, accelerated AIDS progression, and, ultimately, death in chronically SIV-infected macaques after antiretroviral therapy (ART) interruption. Our study further demonstrated that the SIV provirus was preferentially enriched in PD-1 + CD4 + T cells due to their susceptibility to viral entry, potent proliferative ability, and inability to perform viral transcription. In addition, the viral latency was effectively reactivated upon PD-1 blockade. Together, these results suggest that PD-1 blockade may be a double-edged sword for HIV-1 immunotherapy and provide important insight toward the rational design of immunotherapy strategies for an HIV-1 cure. IMPORTANCE As it is one of the most challenging public health problems, there are no clinically effective cure strategies against HIV-1 infection. We demonstrated that prophylactic vaccination combined with PD-1 blockade generated distinct immune response profiles and conferred better control of highly pathogenic SIV mac239 infection in rhesus macaques. In the present study, to our surprise, PD-1 blockade during therapeutic vaccination accelerated the reactivation of latent reservoir and AIDS progression in chronically SIV-infected macaques after ART interruption. Our study further demonstrated that the latent SIV provirus was preferentially enriched in PD-1 + CD4 + T cells because of its susceptibility to viral entry, inhibition of SIV transcription, and potent ability of proliferation, and the viral latency was effectively reactivated by PD-1 blockade. Therefore, PD-1 blockade might be a double-edged sword for AIDS therapy. These findings provoke interest in further exploring novel treatments against HIV-1 infection and other emerging infectious diseases.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    URL: Article
    DOI: 10.1128/jvi.01785-21
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2022
    detail.hit.zdb_id: 1495529-5
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  • 7
    Online Resource
    Online Resource
    Epidemiology and Molecular Characteristics of mcr-9 in Citrobacter spp. from Healthy Individuals and Patients in China
    American Society for Microbiology ; 2022
    In:  Microbiology Spectrum Vol. 10, No. 6 ( 2022-12-21)
    Details
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 10, No. 6 ( 2022-12-21)
    Abstract: With the globally prevailing carbapenemase-producing (CP) Citrobacter spp., polymyxin antibiotics have been reconsidered as one of the last-resort treatment options. Our study was conducted to investigate the prevalence of mcr-9 in Citrobacter species. From October to November 2021, 650 fecal samples and 215 Citrobacter isolates were collected from healthy individuals and infected patients, respectively. Isolates were screened for the presence of the mcr-9 gene by the PCR method. mcr-9 -carrying strains were identified by matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry. Due to the susceptibility to colistin, Citrobacter spp. isolates were first induced to increase the expression of mcr-9 on China blue agar plates containing colistin and were then subjected to conjugation experiments. Whole-genome sequencing was performed on the Illumina NovaSeq PE150 system. The prevalence of mcr-9 in the Citrobacter genus from healthy guts and infected patients was 0.62% and 1.86%, respectively. In all mcr-9 -positive strains, MICs of polymyxin B were observed at ≤2 μg/mL, displaying a nonresistant phenotype. As for conjugation experiments, only one isolate successfully transferred the mcr-9 gene to Escherichia coli C600. Whole-genome sequencing showed that eight mcr-9 -positive Citrobacter isolates carried mcr-9 and genes encoding resistance to beta-lactam antibiotics, including bla CMY , bla DHA , bla SHV , bla TEM , and bla CTX-M . We also discovered that mcr-9 could be located on the pKPC-CAV1321 plasmid. Our study investigated the prevalence of mcr - 9 in Citrobacter spp. in both healthy individuals and infected patients and described the carriage of mcr-9 on the pKPC-CAV1321 plasmid for the first time. IMPORTANCE The emergence of mcr homologues posed a serious threat to the therapeutic efficiency of polymyxin antibiotics. Citrobacter freundii is generally regarded as an opportunistic pathogen associated with a variety of nosocomial infections. In this study, we investigated the prevalence of mcr-9 in Citrobacter spp. isolates from healthy individuals and infected patients and highlighted the importance of the rational use of antibiotics. In addition, this epidemiological investigation is the first to describe the carriage of mcr-9 on plasmid pKPC-CAV1321 and confirms the horizontal transfer of this plasmid. Our research may shed new light on further studies of mcr-9 dissemination in humans.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    URL: Article
    DOI: 10.1128/spectrum.01346-22
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2022
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  • 8
    Online Resource
    Online Resource
    The Sugar Transporter MST1 Is Involved in Colonization of Rhizosphere and Rhizoplane by Metarhizium robertsii
    American Society for Microbiology ; 2021
    In:  mSystems Vol. 6, No. 6 ( 2021-12-21)
    Details
    In: mSystems, American Society for Microbiology, Vol. 6, No. 6 ( 2021-12-21)
    Abstract: It is widely recognized that plant-symbiotic fungi are supported by photosynthates; however, little is known about the molecular mechanisms underlying the utilization of plant-derived sugars by rhizospheric fungi. In the insect-pathogenic and plant-symbiotic fungus Metarhizium robertsii , we previously showed that the utilization of oligosaccharides by the transporter MRT ( Metarhizium raffinose transporter) is important for rhizosphere competency. In this study, we identified a novel monosaccharide transporter (MST1) that is involved in the colonization of the rhizoplane and acts additively with MRT to colonize the rhizosphere. MST1 is not involved in infection of insects by M. robertsii . MST1 is an H + symporter and is able to transport a broad spectrum of monosaccharides, including glucose, sorbose, mannose, rhamnose, and fructose. Deletion of the Mst1 gene impaired germination and mycelial growth in medium containing the sugars that it can transport. Homologs of MST1 were widely found in many fungi, including plant symbionts such as Trichoderma spp. and mycorrhizal fungi and plant pathogens such as Fusarium spp. This work significantly advances insights into the development of symbiotic relationships between plants and fungi. IMPORTANCE Over 90% of all vascular plant species develop an intimate symbiosis with fungi, which has an enormous impact on terrestrial ecosystems. It is widely recognized that plant-symbiotic fungi are supported by photosynthates, but little is known about the mechanisms for fungi to utilize plant-derived carbon sources. In the fungus Metarhizium robertsii , we identified a novel monosaccharide transporter (MST1) that is an H + symporter and can transport a broad spectrum of monosaccharides, including glucose, sorbose, mannose, rhamnose, and fructose. MST1 is involved in the colonization of the rhizoplane and acts additively with the previously characterized oligosaccharide transporter MRT to colonize the rhizosphere. Homologs of MST1 were found in many fungi, including plant symbionts and plant pathogens, suggesting that the utilization of plant-derived sugars by MST1 homologs could also be important for other fungi to develop a symbiotic or parasitic relationship with their respective plant hosts.
    Type of Medium: Online Resource
    ISSN: 2379-5077
    URL: Article
    DOI: 10.1128/mSystems.01277-21
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2021
    detail.hit.zdb_id: 2844333-0
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