Antigens ofAspergillus fumigatusexpressed during infection

1995 ◽  
Vol 73 (S1) ◽  
pp. 1087-1091 ◽  
Author(s):  
Jean-Paul Debeaupuis ◽  
Jacqueline Sarfati ◽  
Hidemitsu Kobayashi ◽  
Drion G. Boucias ◽  
Anne Beauvais ◽  
...  
Keyword(s):  
Invasive Aspergillosis ◽  
Aspergillus Fumigatus ◽  
Virulence Gene ◽  
Culture Conditions ◽  
Infection Process ◽  
Host Cells ◽  
Virulence Determinants

Aspergillus fumigatus secretes an array of antigenic molecules in vitro and in vivo. Recent progresses have been made in the characterization and standardization of A. fumigatus antigens useful for the serodiagnosis of aspergillosis. The chymotrypsin antigen has been purified and can be utilized for the diagnosis of aspergillosis occurring in patients with an immunocompetent B cell population. In the case of immunosuppressed patients suffering from invasive aspergillosis, new methods have been developed to detect the galactofuran containing antigen in the serum. The chemical configuration of this molecule is now known. In contrast to their potential in diagnosis, very little progress has been made on the study of the biochemical and pathoimmunological role of these antigens during the infection process. Two reasons can be advanced for this lack of understanding of the virulence determinants. First of all, antigens studied have been produced in vitro in a dextrose rich medium where pH reaches a value below 5 at maximal growth. These culture conditions are very different from the nutritional environment of the lung, which is a protein-based medium with a slightly basic pH. Antigens expressed under these nutritional conditions are very different from the ones detected in vitro. Second, A. fumigatus is an opportunistic fungus which is characterized by a multifactorial virulence. Gene disruption strategy is not adequate to discriminate the role of a factor in the virulence of the fungus. In contrast, as shown by the studies on two toxins of A. fumigatus, a direct effect of an antigen can be seen directly when several fungal molecules are tested in conjunction on host cells. Key words: Aspergillus fumigatus, antigen, invasive aspergillosis, galactomannan, protease.

scholarly journals In Vitro and In Vivo Characterization of a Bordetella bronchiseptica Mutant Strain with a Deep Rough Lipopolysaccharide Structure

2002 ◽  
Vol 70 (4) ◽  
pp. 1791-1798 ◽  
Author(s):  
Federico Sisti ◽  
Julieta Fernández ◽  
María Eugenia Rodríguez ◽  
Antonio Lagares ◽  
Nicole Guiso ◽  
...  
Keyword(s):  
Parental Strain ◽  
Infection Process ◽  
Bordetella Bronchiseptica ◽  
Host Cells ◽  
Virulence Determinants ◽  
Chronic Infections ◽  
In Vivo Experiments ◽  
Dominant Phenotype

ABSTRACT Bordetella bronchiseptica is closely related to Bordetella pertussis, which produces respiratory disease primarily in mammals other than humans. However, its importance as a human pathogen is being increasingly recognized. Although a large amount of research on Bordetella has been generated regarding protein virulence factors, the participation of the surface lipopolysaccharide (LPS) during B. bronchiseptica infection is less understood. To get a better insight into this matter, we constructed and characterized the behavior of an LPS mutant with the deepest possible rough phenotype. We generated the defective mutant B. bronchiseptica LP39 on the waaC gene, which codes for a heptosyl transferase involved in the biosynthesis of the core region of the LPS molecule. Although in B. bronchiseptica LP39 the production of the principal virulence determinants adenylate cyclase-hemolysin, filamentous hemagglutinin, and pertactin persisted, the quantity of the two latter factors was diminished, with the levels of pertactin being the most greatly affected. Furthermore, the LPS of B. bronchiseptica LP39 did not react with sera obtained from mice that had been infected with the parental strain, indicating that this defective LPS is immunologically different from the wild-type LPS. In vivo experiments demonstrated that the ability to colonize the respiratory tract is reduced in the mutant, being effectively cleared from lungs within 5 days, whereas the parental strain survived at least for 30 days. In vitro experiments have demonstrated that, although B. bronchiseptica LP39 was impaired for adhesion to human epithelial cells, it is still able to survive within the host cells as efficiently as the parental strain. These results seem to indicate that the deep rough form of B. bronchiseptica LPS cannot represent a dominant phenotype at the first stage of colonization. Since isolates with deep rough LPS phenotype have already been obtained from human B. bronchiseptica chronic infections, the possibility that this phenotype arises as a consequence of selection pressure within the host at a late stage of the infection process is discussed.

scholarly journals Efficient Clearance of Aspergillus fumigatus in Murine Lungs by an Ultrashort Antimicrobial Lipopeptide, Palmitoyl-Lys-Ala-dAla-Lys

2008 ◽  
Vol 52 (9) ◽  
pp. 3118-3126 ◽  
Author(s):  
Alexandra Vallon-Eberhard ◽  
Arik Makovitzki ◽  
Anne Beauvais ◽  
Jean-Paul Latgé ◽  
Steffen Jung ◽  
...  
Keyword(s):  
Invasive Aspergillosis ◽  
Aspergillus Fumigatus ◽  
Microscopic Analysis ◽  
Current Standard ◽  
New Family ◽  
Therapeutic Properties ◽  
Survival Assay ◽  
Opportunistic Fungal Pathogen

ABSTRACT Aspergillus fumigatus is an opportunistic fungal pathogen responsible for invasive aspergillosis in immunocompromised individuals. The inefficiency of antifungal agents and high mortality rate resulting from invasive aspergillosis remain major clinical concerns. Recently, we reported on a new family of ultrashort cationic lipopeptides active in vitro against fungi. Mode of action studies supported a membranolytic or a detergent-like effect. Here, we screened several lipopeptides in vitro for their anti-A. fumigatus activity. To investigate the therapeutic properties of the selected peptides in vivo, we challenged immunosuppressed C57BL/6 wild-type mice intranasally with DsRed-labeled A. fumigatus conidia and subsequently treated the animals locally with the lipopeptides. Confocal microscopic analysis revealed the degradation of DsRed-labeled hyphal forms and residual conidia in the lungs of the mice. The most efficient peptide was tested further using a survival assay and was found to significantly prolong the life of the treated animals, whereas no mice survived with the current standard antifungal treatment with amphotericin B. Moreover, as opposed to the drug-treated lungs, the peptide-treated lungs did not display any toxicity of the peptide. Our results highlight the potential of this family of lipopeptides for the treatment of pulmonary invasive aspergillosis.

scholarly journals Aspergillus fumigatus inhibits angiogenesis through the production of gliotoxin and other secondary metabolites

Blood ◽  
2009 ◽  
Vol 114 (26) ◽  
pp. 5393-5399 ◽  
Author(s):  
Ronen Ben-Ami ◽  
Russell E. Lewis ◽  
Konstantinos Leventakos ◽  
Dimitrios P. Kontoyiannis
Keyword(s):  
Invasive Aspergillosis ◽  
Aspergillus Fumigatus ◽  
Capillary Tube ◽  
Umbilical Vein ◽  
Tube Formation ◽  
Dependent Manner ◽  
Antiangiogenic Effect ◽  
Umbilical Vein Endothelial Cells

AbstractIn susceptible hosts, angioinvasion by Aspergillus fumigatus triggers thrombosis, hypoxia, and proinflammatory cytokine release, all of which are stimuli for angiogenesis. We sought to determine whether A fumigatus directly modulates angiogenesis. A fumigatus culture filtrates profoundly inhibited the differentiation, migration, and capillary tube formation of human umbilical vein endothelial cells in vitro. To measure angiogenesis at the site of infection, we devised an in vivo Matrigel assay in cyclophosphamide-treated BALB/c mice with cutaneous invasive aspergillosis. Angiogenesis was significantly suppressed in Matrigel plugs implanted in A fumigatus–infected mice compared with plugs from uninfected control mice. The antiangiogenic effect of A fumigatus was completely abolished by deletion of the global regulator of secondary metabolism, laeA, and to a lesser extent by deletion of gliP, which controls gliotoxin production. Moreover, pure gliotoxin potently inhibited angiogenesis in vitro in a dose-dependent manner. Finally, overexpression of multiple angiogenesis mediator–encoding genes was observed in the lungs of cortisone-treated mice during early invasive aspergillosis, whereas gene expression returned rapidly to baseline levels in cyclophosphamide/cortisone-treated mice. Taken together, these results indicate that suppression of angiogenesis by A fumigatus both in vitro and in a neutropenic mouse model is mediated through secondary metabolite production.

scholarly journals Actin depolymerizing factor controls actin turnover and gliding motility in Toxoplasma gondii

2011 ◽  
Vol 22 (8) ◽  
pp. 1290-1299 ◽  
Author(s):  
Simren Mehta ◽  
L. David Sibley
Keyword(s):  
Toxoplasma Gondii ◽  
Actin Filaments ◽  
Gliding Motility ◽  
Conditional Knockout ◽  
Host Cells ◽  
Actin Binding ◽  
Actin Depolymerizing Factor

Apicomplexan parasites rely on actin-based gliding motility to move across the substratum, cross biological barriers, and invade their host cells. Gliding motility depends on polymerization of parasite actin filaments, yet ∼98% of actin is nonfilamentous in resting parasites. Previous studies suggest that the lack of actin filaments in the parasite is due to inherent instability, leaving uncertain the role of actin-binding proteins in controlling dynamics. We have previously shown that the single allele of Toxoplasma gondii actin depolymerizing factor (TgADF) has strong actin monomer–sequestering and weak filament-severing activities in vitro. Here we used a conditional knockout strategy to investigate the role of TgADF in vivo. Suppression of TgADF led to accumulation of actin-rich filaments that were detected by immunofluorescence and electron microscopy. Parasites deficient in TgADF showed reduced speed of motility, increased aberrant patterns of motion, and inhibition of sustained helical gliding. Lack of TgADF also led to severe defects in entry and egress from host cells, thus blocking infection in vitro. These studies establish that the absence of stable actin structures in the parasite are not simply the result of intrinsic instability, but that TgADF is required for the rapid turnover of parasite actin filaments, gliding motility, and cell invasion.

scholarly journals Conjugation of Hydroxyethyl Starch to Desferrioxamine (DFO) Modulates the Dual Role of DFO in Yersinia enterocolitica Infection

2000 ◽  
Vol 7 (3) ◽  
pp. 457-462 ◽  
Author(s):  
Sören Schubert ◽  
Ingo B. Autenrieth
Keyword(s):  
Yersinia Enterocolitica ◽  
Hydroxyethyl Starch ◽  
Growth Promotion ◽  
Iron Chelator ◽  
Dual Role ◽  
Host Cells ◽  
Immunosuppressive Action

ABSTRACT The iron chelator desferrioxamine (DFO) B is widely used in the therapy of patients with iron overload. As a side effect, DFO may favor the occurrence of fulminant Yersinia infections. Previous work from our laboratory showed that this might be due to a dual role of DFO: growth promotion of the pathogen and immunosuppression of the host. In this study, we sought to determine whether conjugation of DFO to hydroxyethyl starch (HES-DFO) may prevent exacerbation ofYersinia infection in mice. We found HES-DFO to promote neither growth of Yersinia enterocolitica nor mitogen-induced T-cell proliferation and gamma interferon production by T cells in vitro. Nevertheless, in vivo HES-DFO promoted growth ofY. enterocolitica possibly due to cleavage of HES and release of DFO. The pretreatment of mice with DFO resulted in death of all mice 2 to 5 days after application of a normally sublethal inoculum of Y. enterocolitica, while none of the mice pretreated with HES-DFO died within the first 7 days postinfection. However, some of the HES-DFO-treated mice died 8 to 14 days postinfection. Thus, due to the delayed in vivo effect HES-DFO failed to triggerYersinia-induced septic shock, which accounts for early mortality in DFO-associated septicemia. Moreover, our data suggest that DFO needs to be taken up by host cells in order to exert its immunosuppressive action. These results strongly suggest that HES-DFO might be a favorable drug with fewer side effects than DFO in terms of DFO-promoted fulminant infections.

scholarly journals Macrophage Class A Scavenger Receptor-Mediated Phagocytosis of Escherichia coli: Role of Cell Heterogeneity, Microbial Strain, and Culture Conditions In Vitro

2000 ◽  
Vol 68 (4) ◽  
pp. 1953-1963 ◽  
Author(s):  
Leanne Peiser ◽  
Peter J. Gough ◽  
Tatsuhiko Kodama ◽  
Siamon Gordon
Keyword(s):  
Escherichia Coli ◽  
Host Defense ◽  
Bacterial Strain ◽  
Chinese Hamster Ovary Cells ◽  
Culture Conditions ◽  
E Coli ◽  
Class A

ABSTRACT Macrophage class A scavenger receptors (SR-AI and SR-AII) contribute to host defense by binding polyanionic ligands such as lipopolysaccharide and lipoteichoic acid. SR-A knockout (SR-A−/−) mice are more susceptible to endotoxic shock and Listeria monocytogenes infection in vivo, possibly due to decreased clearance of lipopolysaccharide and microorganisms, respectively. We have used flow cytometry to analyze the role of SR-A and other scavenger-like receptors in phagocytosis of bacteria in vitro. Chinese hamster ovary cells stably transfected with human SR-A bound Escherichia coli and Staphylococcus aureus but ingested few organisms. Primary human monocyte-derived macrophages (Mφ) bound and ingested E. coli more efficiently, and this was partially but selectively blocked by the general SR inhibitor, poly(I). A specific and selective role for SR-A was shown, since bone marrow culture-derived Mφ from SR-A−/− mice ingested fewer E. coli organisms than did wild-type cells, while uptake of antibody-opsonized E. coli was unaffected. SR-A-dependent uptake of E. colivaried with the bacterial strain; ingestion of DH5α and K1 by SR-A−/− Mφ was reduced by 30 to 60% and 70 to 75%, respectively. Phagocytosis and endocytosis via SR-A were markedly down-modulated when Mφ were plated on serum-coated tissue culture plastic compared to bacteriologic plastic, where cell adhesion is mediated by SR-A and CR3, respectively. This paper demonstrates that SR-A can bind and ingest bacteria directly, consistent with a role in host defense in vivo, and highlights the importance of the source of the Mφ, bacterial strain, and culture conditions on receptor function in vitro.

scholarly journals Bacillus anthracis Virulence Regulator AtxA Binds Specifically to the pagA Promoter Region

2019 ◽  
Vol 201 (23) ◽  
Author(s):  
Rita M. McCall ◽  
Mary E. Sievers ◽  
Rasem Fattah ◽  
Rodolfo Ghirlando ◽  
Andrei P. Pomerantsev ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Bacillus Anthracis ◽  
Promoter Region ◽  
Virulence Gene ◽  
Anthrax Toxin ◽  
Content Type ◽  
Polymerase Binding

ABSTRACT Anthrax toxin activator (AtxA) is the master virulence gene regulator of Bacillus anthracis. It regulates genes on the chromosome as well as the pXO1 and pXO2 plasmids. It is not clear how AtxA regulates these genes, and direct binding of AtxA to its targets has not been shown. It has been previously suggested that AtxA and other proteins in the Mga/AtxA global transcriptional regulators family bind to the curvature of their DNA targets, although this has never been experimentally proven. Using electrophoretic mobility shift assays, we demonstrate that AtxA binds directly to the promoter region of pagA upstream of the RNA polymerase binding site. We also demonstrate that in vitro, CO2 appears to have no role in AtxA binding. However, phosphomimetic and phosphoablative substitutions in the phosphotransferase system (PTS) regulation domains (PRDs) do appear to influence AtxA binding and pagA regulation. In silico, in vitro, and in vivo analyses demonstrate that one of two hypothesized stem-loops located upstream of the RNA polymerase binding site in the pagA promoter region is important for AtxA binding in vitro and pagA regulation in vivo. Our study clarifies the mechanism by which AtxA interacts with one of its targets. IMPORTANCE Anthrax toxin activator (AtxA) regulates the major virulence genes in Bacillus anthracis. The bacterium produces the anthrax toxins, and understanding the mechanism of toxin production may facilitate the development of therapeutics for B. anthracis infection. Since the discovery of AtxA 25 years ago, the mechanism by which it regulates its targets has largely remained a mystery. Here, we provide evidence that AtxA binds to the promoter region of the pagA gene encoding the main central protective antigen (PA) component of the anthrax toxin. These data suggest that AtxA binding plays a direct role in gene regulation. Our work also assists in clarifying the role of CO2 in AtxA’s gene regulation and provides more evidence for the role of AtxA phosphorylation in virulence gene regulation.

scholarly journals The Bacterial Second Messenger Cyclic di-GMP Regulates Brucella Pathogenesis and Leads to Altered Host Immune Response

2016 ◽  
Vol 84 (12) ◽  
pp. 3458-3470 ◽  
Author(s):  
Mike Khan ◽  
Jerome S. Harms ◽  
Fernanda M. Marim ◽  
Leah Armon ◽  
Cherisse L. Hall ◽  
...  
Keyword(s):  
Immune Response ◽  
Second Messenger ◽  
Host Immune Response ◽  
Vital Role ◽  
Host Cells ◽  
Content Type ◽  
Type Iv

Brucella species are facultative intracellular bacteria that cause brucellosis, a chronic debilitating disease significantly impacting global health and prosperity. Much remains to be learned about how Brucella spp. succeed in sabotaging immune host cells and how Brucella spp. respond to environmental challenges. Multiple types of bacteria employ the prokaryotic second messenger cyclic di-GMP (c-di-GMP) to coordinate responses to shifting environments. To determine the role of c-di-GMP in Brucella physiology and in shaping host- Brucella interactions, we utilized c-di-GMP regulatory enzyme deletion mutants. Our results show that a Δ bpdA phosphodiesterase mutant producing excess c-di-GMP displays marked attenuation in vitro and in vivo during later infections. Although c-di-GMP is known to stimulate the innate sensor STING, surprisingly, the Δ bpdA mutant induced a weaker host immune response than did wild-type Brucella or the low-c-di-GMP guanylate cyclase Δ cgsB mutant. Proteomics analysis revealed that c-di-GMP regulates several processes critical for virulence, including cell wall and biofilm formation, nutrient acquisition, and the type IV secretion system. Finally, Δ bpdA mutants exhibited altered morphology and were hypersensitive to nutrient-limiting conditions. In summary, our results indicate a vital role for c-di-GMP in allowing Brucella to successfully navigate stressful and shifting environments to establish intracellular infection.

scholarly journals Role of the (Mn)superoxide dismutase of Enterococcus faecalis in the in vitro interaction with microglia

Microbiology ◽  
2011 ◽  
Vol 157 (6) ◽  
pp. 1816-1822 ◽  
Author(s):  
Samuele Peppoloni ◽  
Brunella Posteraro ◽  
Bruna Colombari ◽  
Lidia Manca ◽  
Axel Hartke ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Enterococcus Faecalis ◽  
Stress Responses ◽  
Peritoneal Macrophages ◽  
Infection Process ◽  
Microglial Cells ◽  
Infection Model

Enterococcus faecalis is a significant human pathogen worldwide and is responsible for severe nosocomial and community-acquired infections. Although enterococcal meningitis is rare, mortality is considerable, reaching 21 %. Nevertheless, the pathogenetic mechanisms of this infection remain poorly understood, even though the ability of E. faecalis to avoid or survive phagocytic attack in vivo may be very important during the infection process. We previously showed that the manganese-cofactored superoxide dismutase (MnSOD) SodA of E. faecalis was implicated in oxidative stress responses and, interestingly, in the survival within mouse peritoneal macrophages using an in vivo–in vitro infection model. In the present study, we investigated the role of MnSOD in the interaction of E. faecalis with microglia, the brain-resident macrophages. By using an in vitro infection model, murine microglial cells were challenged in parallel with the wild-type strain JH2-2 and its isogenic sodA deletion mutant. While both strains were phagocytosed by microglia efficiently and to a similar extent, the ΔsodA mutant was found to be significantly more susceptible to microglial killing than JH2-2, as assessed by the antimicrobial protection assay. In addition, a significantly higher percentage of acidic ΔsodA-containing phagosomes was found and these also underwent enhanced maturation as determined by the expression of endolysosomal markers. In conclusion, these results show that the MnSOD of E. faecalis contributes to survival of the bacterium in microglial cells by influencing their antimicrobial activity, and this could even be important for intracellular killing in neutrophils and thus for E. faecalis pathogenesis.

scholarly journals Role of G2-S16 Polyanionic Carbosilane Dendrimer in the Prevention of Respiratory Syncytial Virus Infection In Vitro and In Vivo in Mice

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2141
Author(s):  
Ignacio Rodriguez-Izquierdo ◽  
Rafael Ceña-Diez ◽  
Maria Jesús Serramia ◽  
Rosa Rodriguez-Fernández ◽  
Isidoro Martínez ◽  
...  
Keyword(s):  
Respiratory Syncytial Virus ◽  
Cell Surface ◽  
Host Cells ◽  
Carbosilane Dendrimer ◽  
Rsv Infection ◽  
Host Cell Surface ◽  
Syncytial Virus

The respiratory syncytial virus (RSV) causes respiratory infection and bronchiolitis, requiring hospitalization mainly in infants. The interaction between RSV, envelope glycoproteins G and F, and cell surface heparan sulfate proteoglycans (HSPG) is required for binding and entry into the host cells. A G2-S16 polyanionic carbosilane dendrimer was identified as a possible RSV inhibitor. We speculated that the G2-S16 dendrimer adheres to the host cell-surface HSPG, acts through binding to HS receptors, and prevents further RSV infection. The G2-S16 dendrimer was non-toxic when applied intranasally to Balb/c mice, and interestingly enough, this G2-S16 dendrimer inhibits 85% RSV. Therefore, our G2-S16 dendrimer could be a candidate for developing a new possible therapy against RSV infection.

Sign in / Sign up

Export Citation Format

Share Document