In a study designed to determine whether cytotoxic T lymphocytes contribute immunity against influenza virus infection, we inoculated 63 volunteers intranasally with live unattenuated A/Munich/1/79 virus. Over the next seven days clinical observations were made, and amount of shed was measured. The protective effects preinfection serum antibody T-cell A assessed for each participant. All subjects demonstrable responses cleared effectively. This response observed in all age groups, including...

Numerous bacteria secrete low molecular weight compounds termed siderophores that have a high affinity for iron ions. Siderophores well-documented role as iron-scavenging chemicals, chelating ions in the environment whereupon ferrisiderophores reenter bacterial cells by means of specific cell-surface receptors. The is then released incorporation into proteins. Here we show addition to its an iron-scavenger, siderophore pyoverdine secreted Pseudomonas aeruginosa regulates production at least...

ABSTRACT Central to Q fever pathogenesis is replication of the causative agent, Coxiella burnetii , within a phagolysosome-like parasitophorous vacuole (PV) in mononuclear phagocytes. C. modulates PV biogenesis and other host cell functions, such as apoptotic signaling, presumably via activity proteins delivered cytosol by Dot/Icm type IVB secretion system (T4BSS). In this study, we utilized strain carrying IcmD inactivated Himar1 transposon investigate requirements for function parasitism...

ABSTRACT We recently described acidified citrate cysteine medium (ACCM), which supports host cell-free (axenic) growth of Coxiella burnetii . After 6 days incubation, greater than 3 logs was achieved with the avirulent Nine Mile phase II (NMII) strain. Here, we describe modified ACCM and culture conditions that support improved C. their use in genetic transformation pathogen isolation from tissue samples. by replacing fetal bovine serum methyl-β-cyclodextrin to generate ACCM-2. Cultivation...

ABSTRACT Genetically distinct isolates of Coxiella burnetii , the cause human Q fever, display different phenotypes with respect to in vitro infectivity/cytopathology and pathogenicity for laboratory animals. Moreover, correlations between C. genomic groups disease presentation (acute versus chronic) have been described, suggesting that virulence characteristics. To provide a more-complete understanding 's genetic diversity, evolution, pathogenic potential, we deciphered whole-genome...

Summary Under iron‐limiting conditions, Pseudomonas aeruginosa produces a siderophore called pyoverdine. Pyoverdine is secreted into the extracellular environment where it chelates iron, and resulting ferri‐pyoverdine complexes are transported back bacteria by cell surface receptor protein FpvA. also acts as signalling molecule inducing production of three virulence factors. Binding to FpvA transduces signal periplasmic part membrane‐spanning antisigma factor FpvR. The transmitted...

The intracellular bacterial pathogen Coxiella burnetii directs biogenesis of a phagolysosome-like parasitophorous vacuole (PV), in which it replicates. organism encodes Dot/Icm type IV secretion system (T4SS) predicted to deliver the host cytosol effector proteins that mediate PV formation and other cellular events. All C. isolates carry large, autonomously replicating plasmid or have chromosomally integrated plasmid-like sequences (IPS), suggesting IPS genes are critical for infection....

ABSTRACT Coxiella burnetii is an obligate intracellular bacterium that directs biogenesis of a parasitophorous vacuole (PV) for replication. Effectors PV maturation are likely translocated into the host cytosol by type IV secretion system (T4SS) with homology to Dot/Icm apparatus Legionella pneumophila . Since secreted bacterial virulence factors often functionally mimic activities proteins, prokaryotic proteins eukaryotic features considered candidate T4SS substrates. Genes encoding...

Coxiella burnetii, a gram-negative obligate intracellular bacterium, causes human Q fever and is considered potential agent of bioterrorism. Distinct genomic groups C. burnetii are revealed by restriction fragment-length polymorphisms (RFLP). Here we comprehensively define the genetic diversity hybridizing genomes 20 RFLP-grouped four ungrouped isolates from disparate sources to high-density custom Affymetrix GeneChip containing all open reading frames (ORFs) Nine Mile phase I (NMI)...

Coxiella burnetii is a gram-negative obligate intracellular bacterium and the causative agent of human Q fever. The lack methods to genetically manipulate C. significantly impedes study this organism. We describe here cloning characterization ftsZ mutant generated by mariner-based Himar1 transposon (Tn) mutagenesis. was coelectroporated with plasmid encoding C9 transposase variant containing chloramphenicol acetyltransferase, mCherry fluorescent protein, ColE1 origin replication. Vero cells...

ABSTRACT Coxiella burnetii is a ubiquitous zoonotic bacterial pathogen and the cause of human acute Q fever, disabling influenza-like illness. C. 's former obligate intracellular nature significantly impeded genetic characterization putative virulence factors. However, recent host cell-free (axenic) growth organism has enabled development shuttle vector, transposon, inducible gene expression technologies, with targeted inactivation remaining an important challenge. In present study, we...

Significance The vesicular trafficking pathways required for generation of the phagolysosome-like vacuole occupied by Coxiella burnetii are poorly defined, and no pathogen effectors known. Here, we reveal an important role clathrin-mediated in formation identify a type 4B secretion system effector protein [ vacuolar A (CvpA)] that engages this pathway. C . CvpA traffics through endocytic recycling compartment, sorting motifs within bind clathrin adaptor complex AP2. Mutation cvpA , or...

Infections by obligate intracellular bacterial pathogens result in significant morbidity and mortality worldwide. These bacteria include Chlamydia spp., which causes millions of cases sexually transmitted disease blinding trachoma annually, members the α-proteobacterial genera Anaplasma, Ehrlichia, Orientia Rickettsia, agents serious human illnesses including epidemic typhus. Coxiella burnetii, agent Q fever, has also been considered a prototypical bacterium, but recent host cell-free...

The intracellular bacterial pathogen Coxiella burnetii directs biogenesis of a parasitophorous vacuole (PV) that acquires host endolysosomal components. Formation PV supports C. replication requires Dot/Icm type 4B secretion system (T4BSS) delivers effector proteins into the cell cytosol. Thus, subset T4BSS effectors are presumed to direct biogenesis. Recently, PV-localized protein CvpA was found promote growth and expansion. We predict additional localize membrane regulate eukaryotic...

Coxiella burnetii is an intracellular pathogen that causes human Q fever, a disease normally presents as severe flu-like illness. Due to high infectivity and severity, the considered risk group 3 organism. Full-length lipopolysaccharide (LPS) required for full virulence by C. only factor currently defined infection of immunocompetent animal. Transition virulent phase I bacteria with smooth LPS, avirulent II rough occurs during in vitro passage. Semi-rough intermediate forms are also...

Scrub typhus is an understudied, potentially fatal infection that threatens one billion persons in the Asia-Pacific region. How causative obligate intracellular bacterium, Orientia tsutsugamushi facilitates its survival and pathogenesis poorly understood. Many bacterial pathogens utilize Type 1 (T1SS) or 4 secretion system (T4SS) to translocate ankyrin repeat-containing proteins (Anks) traffic distinct subcellular locations modulate host cell processes. The O. genome encodes of largest known...

Host cell-free (axenic) culture of Coxiella burnetii in acidified citrate cysteine medium-2 (ACCM-2) has provided important opportunities for investigating the biology this naturally obligate intracellular pathogen and enabled development tools genetic manipulation. However, ACCM-2 complex nutrient sources that preclude a detailed study nutritional factors required C. growth. Metabolic reconstruction predicts bacterium cannot synthesize all amino acids therefore must sequester some from...

A hallmark of Coxiella burnetii, the bacterial cause human Q fever, is a biphasic developmental cycle that generates biologically, ultrastructurally, and compositionally distinct large cell variant (LCV) small (SCV) forms. LCVs are replicating, exponential phase forms while SCVs non-replicating, stationary The SCV has several properties, such as condensed nucleoid an unusual envelope, suspected conferring enhanced environmental stability. To identify genetic determinants LCV to transition,...

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in immunocompromised individuals is associated with prolonged virus shedding and evolution of viral variants. Rapamycin its analogs (rapalogs, including everolimus, temsirolimus, ridaforolimus) are FDA approved as mTOR inhibitors for the treatment human diseases, cancer autoimmunity. Rapalog use commonly an increased susceptibility to infection, which has been traditionally explained by impaired adaptive immunity. Here,...

ABSTRACT Q fever is a widespread zoonosis caused by Coxiella burnetii . Diagnosis of usually based on serological testing patient serum. The diagnostic antigen test kits formalin-fixed phase I and II organisms the Nine Mile reference strain. Deficiencies this include (i) potential for cross-reactivity with other pathogens; (ii) an inability to distinguish between C. strains; (iii) need propagate purify , difficult potentially hazardous process. Consequently, there sensitive specific...

Coxiella burnetii is an intracellular, gram-negative bacterium that causes the zoonosis Q fever. This disease typically presents as acute flu-like illness with persistent, focalized infections occurring less frequently. Clinical outcomes of fever have been associated distinct genomic groups C. burnetii, suggesting gene content responsible for virulence potential. To investigate this hypothesis, thirteen strains (representing I-VI) was evaluated in a guinea pig infection model by...

Repurposing FDA-approved drugs that treat respiratory infections caused by coronaviruses, such as SARS-CoV-2 and MERS-CoV, could quickly provide much needed antiviral therapies. In the current study, potency cellular toxicity of four fluoroquinolones (enoxacin, ciprofloxacin, levofloxacin, moxifloxacin) were assessed in Vero cells A549 engineered to overexpress ACE2, entry receptor. All suppressed replication at high micromolar concentrations both cell types, with enoxacin demonstrating...

A variety of immunolabeling procedures for both light and electron microscopy were used to examine the cellular origins host membranes supporting SARS-CoV-2 replication complex. The endoplasmic reticulum has long been implicated as a source membrane coronavirus organelle. Using dsRNA marker sites viral RNA synthesis, we provide additional evidence ER prominent membrane. In addition, observed rapid fragmentation Golgi apparatus which is visible by 6 h complete 12 post-infection. derived lipid...