scholarly journals Insertion sequences drive the emergence of a highly adapted human pathogen

2020 ◽  
Vol 6 (9) ◽  
Author(s):  
Erwin Sentausa ◽  
Pauline Basso ◽  
Alice Berry ◽  
Annie Adrait ◽  
Gwendoline Bellement ◽  
...  
Keyword(s):  
Galleria Mellonella ◽  
Opportunistic Pathogen ◽  
Insertion Sequences ◽  
Pathogenic Potential ◽  
Highly Pathogenic ◽  
Type Iv ◽  
Genome Wide ◽  
Outer Membrane Porin ◽  
Specific Antigens ◽  
Different Levels

Pseudomonas aeruginosa is a highly adaptive opportunistic pathogen that can have serious health consequences in patients with lung disorders. Taxonomic outliers of P. aeruginosa of environmental origin have recently emerged as infectious for humans. Here, we present the first genome-wide analysis of an isolate that caused fatal haemorrhagic pneumonia. In two clones, CLJ1 and CLJ3, sequentially recovered from a patient with chronic pulmonary disease, insertion of a mobile genetic element into the P. aeruginosa chromosome affected major virulence-associated phenotypes and led to increased resistance to the antibiotics used to combat the infection. Comparative genome, proteome and transcriptome analyses revealed that this ISL3-family insertion sequence disrupted the genes for flagellar components, type IV pili, O-specific antigens, translesion polymerase and enzymes producing hydrogen cyanide. Seven-fold more insertions were detected in the later isolate, CLJ3, than in CLJ1, some of which modified strain susceptibility to antibiotics by disrupting the genes for the outer-membrane porin OprD and the regulator of β-lactamase expression AmpD. In the Galleria mellonella larvae model, the two strains displayed different levels of virulence, with CLJ1 being highly pathogenic. This study revealed insertion sequences to be major players in enhancing the pathogenic potential of a P. aeruginosa taxonomic outlier by modulating both its virulence and its resistance to antimicrobials, and explains how this bacterium adapts from the environment to a human host.

scholarly journals Insertion sequences drive the emergence of a highly adapted human pathogen

2018 ◽  
Author(s):  
Erwin Sentausa ◽  
Pauline Basso ◽  
Alice Berry ◽  
Annie Adrait ◽  
Gwendoline Bellement ◽  
...  
Keyword(s):  
Galleria Mellonella ◽  
Pathogenic Potential ◽  
Highly Pathogenic ◽  
Type Iv ◽  
Genome Wide ◽  
Outer Membrane Porin ◽  
Hemorrhagic Pneumonia ◽  
Genes Encoding ◽  
Specific Antigens ◽  
Different Levels

AbstractTaxonomic outliers of Pseudomonas aeruginosa of environmental origin have recently emerged as infectious for humans. Here we present the first genome-wide analysis of an isolate that caused fatal hemorrhagic pneumonia. We demonstrate that, in two sequential clones, CLJ1 and CLJ3, recovered from a patient with chronic pulmonary disease, insertion of a mobile genetic element into the P. aeruginosa chromosome affected major virulence-associated phenotypes and led to increased resistance to antibiotics used to treat the patient. Comparative proteome and transcriptome analyses revealed that this insertion sequence, ISL3, disrupted genes encoding flagellar components, type IV pili, O-specific antigens, translesion polymerase and enzymes producing hydrogen cyanide. CLJ3 possessed seven fold more IS insertions than CLJ1, some modifying its susceptibility to antibiotics by disrupting the genes for the outer-membrane porin OprD and the regulator of β-lactamase expression AmpD. In the Galleria mellonella larvae model, the two strains displayed different levels of virulence, with CLJ1 being highly pathogenic. This work reveals ISs as major players in enhancing the pathogenic potential of a P. aeruginosa taxonomic outlier by modulating both, the virulence and the resistance to antimicrobials, and explains the ability of this bacterium to adapt from the environment to a human host.

scholarly journals Mouse Macrophages Are Permissive to Motile Legionella Species That Fail To Trigger Pyroptosis

2009 ◽  
Vol 78 (1) ◽  
pp. 423-432 ◽  
Author(s):  
Natalie N. Whitfield ◽  
Brenda G. Byrne ◽  
Michele S. Swanson
Keyword(s):  
Cell Death ◽  
Legionella Pneumophila ◽  
Defense Mechanisms ◽  
Opportunistic Pathogen ◽  
Pathogenic Potential ◽  
Innate Defense ◽  
Transplant Patients ◽  
Type Iv ◽  
Mouse Macrophages ◽  
Motile Species

ABSTRACT Legionella pneumophila, a motile opportunistic pathogen of humans, is restricted from replicating in the lungs of C57BL/6 mice. Resistance of mouse macrophages to L. pneumophila depends on recognition of cytosolic flagellin. Once detected by the NOD-like receptors Naip5 and Ipaf (Nlrc4), flagellin triggers pyroptosis, a proinflammatory cell death. In contrast, motile strains of L. parisiensis and L. tucsonensis replicate profusely within C57BL/6 macrophages, similar to flagellin-deficient L. pneumophila. To gain insight into how motile species escape innate defense mechanisms of mice, we compared their impacts on macrophages. L. parisiensis and L. tucsonensis do not induce proinflammatory cell death, as measured by lactate dehydrogenase (LDH) release and interleukin-1β (IL-1β) secretion. However, flagellin isolated from L. parisiensis and L. tucsonensis triggers cell death and IL-1β secretion when transfected into the cytosol of macrophages. Neither strain displays three characteristics of the canonical L. pneumophila Dot/Icm type IV secretion system: sodium sensitivity, LAMP-1 evasion, and pore formation. Therefore, we postulate that when L. parisiensis and L. tucsonensis invade a mouse macrophage, flagellin is confined to the phagosome, protecting the bacteria from recognition by the cytosolic surveillance system and allowing Legionella to replicate. Despite their superior capacity to multiply in mouse macrophages, L. parisiensis and L. tucsonensis have been associated with only two cases of disease, both in renal transplant patients. These results point to the complexity of disease, a product of the pathogenic potential of the microbe, as defined in the laboratory, and the capacity of the host to mount a measured defense.

scholarly journals Genetic and virulence variation in an environmental population of the opportunistic pathogen Aspergillus fumigatus

Microbiology ◽  
2014 ◽  
Vol 160 (4) ◽  
pp. 742-751 ◽  
Author(s):  
Fadwa Alshareef ◽  
Geoffrey D. Robson
Keyword(s):  
Aspergillus Fumigatus ◽  
Galleria Mellonella ◽  
Rapd Analysis ◽  
Opportunistic Pathogen ◽  
Clinical Isolates ◽  
Environmental Isolates ◽  
Pathogenic Potential ◽  
Patient Infection ◽  
Selection Of ◽  
Virulence Variation

Environmental populations of the opportunistic pathogen Aspergillus fumigatus have been shown to be genotypically diverse and to contain a range of isolates with varying pathogenic potential. In this study, we combined two RAPD primers to investigate the genetic diversity of environmental isolates from Manchester collected monthly over 1 year alongside Dublin environmental isolates and clinical isolates from patients. RAPD analysis revealed a diverse genotype, but with three major clinical isolate clusters. When the pathogenicity of clinical and Dublin isolates was compared with a random selection of Manchester isolates in a Galleria mellonella larvae model, as a group, clinical isolates were significantly more pathogenic than environmental isolates. Moreover, when relative pathogenicity of individual isolates was compared, clinical isolates were the most pathogenic, Dublin isolates were the least pathogenic and Manchester isolates showed a range in pathogenicity. Overall, this suggests that the environmental population is genetically diverse, displaying a range in pathogenicity, and that the most pathogenic strains from the environment are selected during patient infection.

scholarly journals Disparate Subcellular Localization Patterns of Pseudomonas aeruginosa Type IV Pilus ATPases Involved in Twitching Motility

2005 ◽  
Vol 187 (3) ◽  
pp. 829-839 ◽  
Author(s):  
Poney Chiang ◽  
Marc Habash ◽  
Lori L. Burrows
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Fluorescent Protein ◽  
Protein Localization ◽  
Yellow Fluorescent Protein ◽  
Distribution Patterns ◽  
Opportunistic Pathogen ◽  
Twitching Motility ◽  
Polar Localization ◽  
Type Iv ◽  
And Function

ABSTRACT The opportunistic pathogen Pseudomonas aeruginosa expresses polar type IV pili (TFP), which are responsible for adhesion to various materials and twitching motility on surfaces. Twitching occurs by alternate extension and retraction of TFP, which arise from assembly and disassembly of pilin subunits at the base of the pilus. The ATPase PilB promotes pilin assembly, while the ATPase PilT or PilU or both promote pilin dissociation. Fluorescent fusions to two of the three ATPases (PilT and PilU) were functional, as shown by complementation of the corresponding mutants. PilB and PilT fusions localized to both poles, while PilU fusions localized only to the piliated pole. To identify the portion of the ATPases required for localization, sequential C-terminal deletions of PilT and PilU were generated. The conserved His and Walker B boxes were dispensable for polar localization but were required for twitching motility, showing that localization and function could be uncoupled. Truncated fusions that retained polar localization maintained their distinctive distribution patterns. To dissect the cellular factors involved in establishing polarity, fusion protein localization was monitored with a panel of TFP mutants. The localization of yellow fluorescent protein (YFP)-PilT and YFP-PilU was independent of the subunit PilA, other TFP ATPases, and TFP-associated proteins previously shown to be associated with the membrane or exhibiting polar localization. In contrast, YFP-PilB exhibited diffuse cytoplasmic localization in a pilC mutant, suggesting that PilC is required for polar localization of PilB. Finally, localization studies performed with fluorescent ATPase chimeras of PilT and PilU demonstrated that information responsible for the characteristic localization patterns of the ATPases likely resides in their N termini.

scholarly journals Genetic and phenotypic analysis of the pathogenic potential of two novel Chlamydia gallinacea strains compared to Chlamydia psittaci

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Marloes Heijne ◽  
Martina Jelocnik ◽  
Alexander Umanets ◽  
Michael S. M. Brouwer ◽  
Annemieke Dinkla ◽  
...  
Keyword(s):  
Virulence Factors ◽  
Opportunistic Pathogen ◽  
Chlamydia Psittaci ◽  
Phenotypic Analysis ◽  
Pathogenic Potential ◽  
The Family ◽  
Chicken Eggs ◽  
Sequence Types ◽  
Insight Into ◽  
Embryonated Chicken

AbstractChlamydia gallinacea is an obligate intracellular bacterium that has recently been added to the family of Chlamydiaceae. C. gallinacea is genetically diverse, widespread in poultry and a suspected cause of pneumonia in slaughterhouse workers. In poultry, C. gallinacea infections appear asymptomatic, but studies about the pathogenic potential are limited. In this study two novel sequence types of C. gallinacea were isolated from apparently healthy chickens. Both isolates (NL_G47 and NL_F725) were closely related to each other and have at least 99.5% DNA sequence identity to C. gallinacea Type strain 08-1274/3. To gain further insight into the pathogenic potential, infection experiments in embryonated chicken eggs and comparative genomics with Chlamydia psittaci were performed. C. psittaci is a ubiquitous zoonotic pathogen of birds and mammals, and infection in poultry can result in severe systemic illness. In experiments with embryonated chicken eggs, C. gallinacea induced mortality was observed, potentially strain dependent, but lower compared to C. psittaci induced mortality. Comparative analyses confirmed all currently available C. gallinacea genomes possess the hallmark genes coding for known and potential virulence factors as found in C. psittaci albeit to a reduced number of orthologues or paralogs. The presence of potential virulence factors and the observed mortality in embryonated eggs indicates C. gallinacea should rather be considered as an opportunistic pathogen than an innocuous commensal.

scholarly journals Antimicrobial susceptibility and pathogenicity of Escherichia coli strains of environmental origin

2015 ◽  
Vol 45 (7) ◽  
pp. 1249-1255 ◽  
Author(s):  
Daiane Carvalho ◽  
Fabrine Finkler ◽  
Tiela Trapp Grassotti ◽  
Hiran Castagnino Kunert Filho ◽  
Francisco Esmaile de Sales Lima ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Susceptibility ◽  
Disc Diffusion ◽  
Diffusion Test ◽  
Pathogenic Potential ◽  
Highly Pathogenic ◽  
E Coli ◽  
Intermediate Degree

The study aimed to evaluate the antimicrobial susceptibility of 109 samples of Escherichia coli (E. coli) of environmental origin and to characterize these isolates according to the degree of pathogenicity in vivo, verifying a possible relationship between this variable and susceptibility to the active principles tested. The isolates were subjected to disc diffusion test to 14 antibiotics. From 16.5% to 90% of the samples were sensitive; 1 - 28.5% showed intermediate degree of susceptibility and between 9 to 78% of E. coli analyzed were resistant. The highest resistance percentages were seen in the class of quinolones and tetracyclines (>75%), and for sensitivity in the class of amphenicols (68.8%). By inoculating 1- day - old chicks, the isolates were classified as highly pathogenic (2.7%), intermediate (10.1%), low (42.2%) and apathogenic (45%). It was observed a wide variation in the susceptibility profile of isolates in relation to antimicrobials. It was also found that most of the samples had pathogenic potential (55%), thus being considered as APEC (avian pathogenic E. coli). No relationship between pathogenicity and antimicrobial susceptibility (P≤0.05) was observed.

scholarly journals Cryo-EM reveals new species-specific proteins and symmetry elements in the Legionella pneumophila Dot/Icm T4SS

2021 ◽  
Author(s):  
Michael J Sheedlo ◽  
Clarissa L Durie ◽  
Jeong Min Chung ◽  
Louise Chang ◽  
Michele Swanson ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Genetic Locus ◽  
Opportunistic Pathogen ◽  
Effector Proteins ◽  
Large Set ◽  
Type Iv ◽  
Specific Proteins ◽  
Multiple Conformations ◽  
Membrane Spanning ◽  
Species Specific

Legionella pneumophila is an opportunistic pathogen that causes the potentially fatal pneumonia known as Legionnaires’ Disease. The pathology associated with infection depends on bacterial delivery of effector proteins into the host via the membrane spanning Dot/Icm type IV secretion system (T4SS). We have determined sub-3.0 Å resolution maps of the Dot/Icm T4SS core complex by single particle cryo-EM. The high-resolution structural analysis has allowed us to identify proteins encoded outside the Dot/Icm genetic locus that contribute to the core T4SS structure. We can also now define two distinct areas of symmetry mismatch, one that connects the C18 periplasmic ring (PR) and the C13 outer membrane cap (OMC) and one that connects the C13 OMC with a 16-fold symmetric dome. Unexpectedly the connection between the PR and OMC is DotH, with five copies sandwiched between the OMC and PR to accommodate the symmetry mismatch. Finally, we observe multiple conformations in the reconstructions that indicate flexibility within the structure. We hypothesize this conformational flexibility is likely to facilitate the Dot/Icm T4SS’s ability to translocate a remarkably large set of ~300 putative substrates across the inner and outer membranes of the bacterial cell.

scholarly journals An Update on Animal Models for Severe Acute Respiratory Syndrome Coronavirus 2 Infection and Countermeasure Development

2021 ◽  
Vol 12 ◽  
Author(s):  
Liang Zhang ◽  
Shuaiyin Chen ◽  
Weiguo Zhang ◽  
Haiyan Yang ◽  
Yuefei Jin ◽  
...  
Keyword(s):  
Animal Models ◽  
Severe Acute Respiratory Syndrome ◽  
Research Progress ◽  
Laboratory Mice ◽  
Disease Manifestation ◽  
Highly Pathogenic ◽  
The World ◽  
Coronavirus Infection ◽  
Different Levels ◽  
Critical Aspects

Coronavirus Disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a pandemic since March 2020 and led to significant challenges to over 200 countries and regions all over the world. The establishment of highly pathogenic coronavirus animal model is beneficial for the study of vaccines and pathogenic mechanism of the virus. Laboratory mice, Syrian hamsters, Non-human primates and Ferrets have been used to establish animal models of emerging coronavirus infection. Different animal models can reproduce clinical infection symptoms at different levels. Appropriate animal models are of great significance for the pathogenesis of COVID-19 and the research progress related to vaccines. This review aims to introduce the current progress about experimental animal models for SARS-CoV-2, and collectively generalize critical aspects of disease manifestation in humans and increase their usefulness in research into COVID-19 pathogenesis and developing new preventions and treatments.

scholarly journals Probabilistic data integration identifies reliable gametocyte-specific proteins and transcripts in malaria parasites

2017 ◽  
Author(s):  
Lisette Meerstein-Kessel ◽  
Robin van der Lee ◽  
Will Stone ◽  
Kjerstin Lanke ◽  
David A Baker ◽  
...  
Keyword(s):  
Transcript Abundance ◽  
Data Sets ◽  
Asexual Blood Stage ◽  
Systematic Analysis ◽  
Humoral Immune ◽  
Proteomic Data ◽  
Genome Wide ◽  
Field Samples ◽  
Specific Proteins ◽  
Specific Antigens

AbstractPlasmodium gametocytes are the sexual forms of the malaria parasite essential for transmission to mosquitoes. To better understand how gametocytes differ from asexual blood-stage parasites, we performed a systematic analysis of available ‘omics data for P. falciparum and other Plasmodium species. 18 transcriptomic and proteomic data sets were evaluated for the presence of curated “gold standards” of 41 gametocyte-specific versus 46 non-gametocyte genes and integrated using Bayesian probabilities, resulting in gametocyte-specificity scores for all P. falciparum genes.To illustrate the utility of the gametocyte score, we explored newly predicted gametocyte-specific genes as potential biomarkers of gametocyte carriage and exposure. We analyzed the humoral immune response in field samples against 30 novel gametocyte-specific antigens and found five antigens to be differentially recognized by gametocyte carriers as compared to malaria-infected individuals without detectable gametocytes. We also validated the gametocyte-specificity of 15 identified gametocyte transcripts on culture material and samples from naturally infected individuals, resulting in eight transcripts that were >1000-fold higher expressed in gametocytes compared to asexual parasites and whose transcript abundance allowed gametocyte detection in naturally infected individuals. Our integrated genome-wide gametocyte-specificity scores provide a comprehensive resource to identify targets and monitor P. falciparum gametocytemia.

scholarly journals Robust, Comprehensive Molecular, and Phenotypical Characterisation of Atypical Candida albicans Clinical Isolates From Bogotá, Colombia

2020 ◽  
Vol 10 ◽  
Author(s):  
Giovanni Rodríguez-Leguizamón ◽  
Andrés Ceballos-Garzón ◽  
Carlos F. Suárez ◽  
Manuel A. Patarroyo ◽  
Claudia M. Parra-Giraldo
Keyword(s):  
Candida Albicans ◽  
Galleria Mellonella ◽  
Opportunistic Pathogen ◽  
Clinical Isolates ◽  
High Genetic Diversity ◽  
Cluster Membership ◽  
Protein Mass ◽  
Molecular Tests ◽  
Well Differentiated ◽  
Clade 1

Candida albicans is commensal in human microbiota and is known to be the commonest opportunistic pathogen, having variable clinical outcomes that can lead to up to 60% mortality. Such wide clinical behaviour can be attributed to its phenotypical plasticity and high genetic diversity. This study characterised 10 Colombian clinical isolates which had already been identified as C. albicans by molecular tests; however, previous bioinformatics analysis of protein mass spectra and phenotypical characteristics has shown that this group of isolates has atypical behaviour, sharing characteristics of both C. africana and C. albicans. This study was aimed at evaluating atypical isolates’ pathogenic capability in the Galleria mellonella model; susceptibility profiles were determined and MLST was used for molecular characterisation. Cluster analysis, enabling unbiased bootstrap to classify the isolates and establish their cluster membership and e-BURST, was used for establishing clonal complexes (CC). Both approaches involved using representative MLST data from the 18 traditional C. albicans clades, as well as C. albicans-associated and minor species. Ten atypical isolates were distributed as follows: 6/10 (B71, B41, B60, R6, R41, and R282) were grouped into a statistically well-supported atypical cluster (AC) and constituted a differentiated CC 6; 2/10 of the isolates were clearly grouped in clade 1 and were concurrent in CC 4 (B80, B44). Another 2/10 atypical isolates were grouped in clade 10 and concurred in CC 7 (R425, R111); most atypical isolates were related to geographically distant isolates and some represented new ST. Isolates B41 and R41 in the AC had greater virulence. Isolate B44 was fluconazole-resistant and was grouped in clade 1. The atypical nature of the isolates studied here was demonstrated by the contrast between phenotypical traits (C. africana-like), molecular markers (C. albicans-like), virulence, and antifungal resistance, highlighting the widely described genetic plasticity for this genus. Our results showed that the atypical isolates forming well-differentiated groups belonged to C. albicans. Our findings could contribute towards developing molecular epidemiology approaches for managing hospital-acquired infection.

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