scholarly journals Embryonated Eggs as an Alternative Infection Model To Investigate Aspergillus fumigatus Virulence

2010 ◽  
Vol 78 (7) ◽  
pp. 2995-3006 ◽  
Author(s):  
Ilse D. Jacobsen ◽  
Katharina Große ◽  
Silvia Slesiona ◽  
Bernhard Hube ◽  
Angela Berndt ◽  
...  
Keyword(s):  
Low Cost ◽  
Animal Experiments ◽  
Infection Model ◽  
Egg Survival ◽  
Chemokine Production ◽  
Rapid Construction ◽  
Infection Models ◽  
Invertebrate Models

ABSTRACT Infection models are essential tools for studying microbial pathogenesis. Murine models are considered the “gold standard” for studying in vivo infections caused by Aspergillus species, such as A. fumigatus. Recently developed molecular protocols allow rapid construction of high numbers of fungal deletion mutants, and alternative infection models based on cell culture or invertebrates are widely used for screening such mutants to reduce the number of rodents in animal experiments. To bridge the gap between invertebrate models and mice, we have developed an alternative, low-cost, and easy-to-use infection model for Aspergillus species based on embryonated eggs. The outcome of infections in the egg model is dose and age dependent and highly reproducible. We show that the age of the embryos affects the susceptibility to A. fumigatus and that increased resistance coincides with altered chemokine production after infection. The progress of disease in the model can be monitored by using egg survival and histology. Based on pathological analyses, we hypothesize that invasion of embryonic membranes and blood vessels leads to embryonic death. Defined deletion mutant strains previously shown to be fully virulent or partially or strongly attenuated in a mouse model of bronchopulmonary aspergillosis showed comparable degrees of attenuation in the egg model. Addition of nutrients restored the reduced virulence of a mutant lacking a biosynthetic gene, and variations of the infectious route can be used to further analyze the role of distinct genes in our model. Our results suggest that embryonated eggs can be a very useful alternative infection model to study A. fumigatus virulence and pathogenicity.

Challenges with Wound Infection Models in Drug Development

2020 ◽  
Vol 21 (13) ◽  
pp. 1301-1312 ◽  
Author(s):  
Sandeep K. Shukla ◽  
Ajay K. Sharma ◽  
Vanya Gupta ◽  
Aman Kalonia ◽  
Priyanka Shaw
Keyword(s):  
Wound Healing ◽  
Wound Infection ◽  
Chronic Wound ◽  
Wound Care ◽  
Infection Model ◽  
In Vivo Models ◽  
Infection Models

: Wound research is an evolving science trying to unfold the complex untold mechanisms behind the wound healing cascade. In particular, interest is growing regarding the role of microorganisms in both acute and chronic wound healing. Microbial burden plays an important role in the persistence of chronic wounds, ultimately resulting in delayed wound healing. It is therefore important for clinicians to understand the evolution of infection science and its various etiologies. Therefore, to understand the role of bacterial biofilm in chronic wound pathogenesis, various in vitro and in vivo models are required to investigate biofilms in wound-like settings. Infection models should be refined comprising an important signet of biofilms. These models are eminent for translational research to obtain data for designing an improved wound care formulation. However, all the existing models possess limitations and do not fit properly in the model frame for developing wound care agents. Among various impediments, one of the major drawbacks of such models is that the wound they possess does not mimic the wound a human develops. Therefore, a novel wound infection model is required which can imitate the human wounds. : This review article mainly discusses various in vitro and in vivo models showing microbial colonization, their advantages and challenges. Apart from these models, there are also present ex vivo wound infection models, but this review mainly focused on various in vitro and in vivo models available for studying wound infection in controlled conditions. This information might be useful in designing an ideal wound infection model for developing an effective wound healing formulation.

scholarly journals Type VI secretion system and its effectors PdpC, PdpD and OpiA contribute to Francisella virulence in Galleria mellonella larvae

2021 ◽  
Author(s):  
Maj Brodmann ◽  
Sophie Schnider ◽  
Marek Basler
Keyword(s):  
Galleria Mellonella ◽  
Response Regulator ◽  
Infection Model ◽  
Type Vi Secretion System ◽  
Infectious Dose ◽  
Infection Models

Francisella tularensis causes the deadly zoonotic disease tularemia in humans and is able to infect a broad range of organisms including arthropods, which are thought to play a major role in Francisella transmission. However, while mammalian in vitro and in vivo infection models are widely used to investigate Francisella pathogenicity, a detailed characterization of the major Francisella virulence factor, a non-canonical T6SS, in an arthropod in vivo infection model is missing. Here we use Galleria mellonella larvae to analyze the role of the Francisella T6SS and its corresponding effectors in F. novicida virulence. We report that G. mellonella larvae killing depends on the functional T6SS and infectious dose. In contrast to other mammalian in vivo infection models, even one of PdpC, PdpD or OpiA T6SS effectors is sufficient to kill G. mellonella larvae while sheath recycling by ClpB is dispensable. We further demonstrate that treatment by polyethylene glycol (PEG) activates Francisella T6SS in liquid culture and that this is independent of the response regulator PmrA. PEG-activated IglC secretion is dependent on T6SS structural component PdpB but independent of putative effectors PdpC, PdpD, AnmK and OpiB1-3. The results of larvae infection and secretion assay suggest that AnmK, a putative T6SS component with unknown function, interferes with OpiA-mediated toxicity but not with general T6SS activity. We establish that the easy-to-use G. mellonella larvae infection model provides new insights into function of T6SS and pathogenesis of Francisella.

scholarly journals Activity of the Pore-Forming Virulence Factor Listeriolysin O Is Reversibly Inhibited by Naturally Occurring S-Glutathionylation

2017 ◽  
Vol 85 (4) ◽  
Author(s):  
Jonathan L. Portman ◽  
Qiongying Huang ◽  
Michelle L. Reniere ◽  
Anthony T. Iavarone ◽  
Daniel A. Portnoy
Keyword(s):  
Protein Function ◽  
Inhibitory Effect ◽  
Cysteine Residue ◽  
Infection Model ◽  
Listeriolysin O ◽  
Content Type ◽  
Pore Forming Proteins

ABSTRACT Cholesterol-dependent cytolysins (CDCs) represent a family of homologous pore-forming proteins secreted by many Gram-positive bacterial pathogens. CDCs mediate membrane binding partly through a conserved C-terminal undecapeptide, which contains a single cysteine residue. While mutational changes to other residues in the undecapeptide typically have severe effects, mutation of the cysteine residue to alanine has minor effects on overall protein function. Thus, the role of this highly conserved reactive cysteine residue remains largely unknown. We report here that the CDC listeriolysin O (LLO), secreted by the facultative intracellular pathogen Listeria monocytogenes, was posttranslationally modified by S-glutathionylation at this conserved cysteine residue and that either endogenously synthesized or exogenously added glutathione was sufficient to form this modification. When recapitulated with purified protein in vitro, this modification completely ablated the activity of LLO, and this inhibitory effect was fully reversible by treatment with reducing agents. A cysteine-to-alanine mutation in LLO rendered the protein completely resistant to inactivation by S-glutathionylation, and a mutant expressing this mutation retained full hemolytic activity. A mutant strain of L. monocytogenes expressing the cysteine-to-alanine variant of LLO was able to infect and replicate within bone marrow-derived macrophages indistinguishably from the wild type in vitro, yet it was attenuated 4- to 6-fold in a competitive murine infection model in vivo. This study suggests that S-glutathionylation may represent a mechanism by which CDC-family proteins are posttranslationally modified and regulated and help explain an evolutionary pressure to retain the highly conserved undecapeptide cysteine.

scholarly journals Corneal Infection Models: Tools to Investigate the Role of Biofilms in Bacterial Keratitis

Cells ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 2450
Author(s):  
Lucy Urwin ◽  
Katarzyna Okurowska ◽  
Grace Crowther ◽  
Sanhita Roy ◽  
Prashant Garg ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Bacterial Species ◽  
Resistance Mechanisms ◽  
Bacterial Keratitis ◽  
Corneal Surface ◽  
Corneal Infection ◽  
Infection Models

Bacterial keratitis is a corneal infection which may cause visual impairment or even loss of the infected eye. It remains a major cause of blindness in the developing world. Staphylococcus aureus and Pseudomonas aeruginosa are common causative agents and these bacterial species are known to colonise the corneal surface as biofilm populations. Biofilms are complex bacterial communities encased in an extracellular polymeric matrix and are notoriously difficult to eradicate once established. Biofilm bacteria exhibit different phenotypic characteristics from their planktonic counterparts, including an increased resistance to antibiotics and the host immune response. Therefore, understanding the role of biofilms will be essential in the development of new ophthalmic antimicrobials. A brief overview of biofilm-specific resistance mechanisms is provided, but this is a highly multifactorial and rapidly expanding field that warrants further research. Progression in this field is dependent on the development of suitable biofilm models that acknowledge the complexity of the ocular environment. Abiotic models of biofilm formation (where biofilms are studied on non-living surfaces) currently dominate the literature, but co-culture infection models are beginning to emerge. In vitro, ex vivo and in vivo corneal infection models have now been reported which use a variety of different experimental techniques and animal models. In this review, we will discuss existing corneal infection models and their application in the study of biofilms and host-pathogen interactions at the corneal surface.

scholarly journals Atovaquone and ELQ-300 Combination Therapy as a Novel Dual-Site Cytochromebc1Inhibition Strategy for Malaria

2016 ◽  
Vol 60 (8) ◽  
pp. 4853-4859 ◽  
Author(s):  
Allison M. Stickles ◽  
Martin J. Smilkstein ◽  
Joanne M. Morrisey ◽  
Yuexin Li ◽  
Isaac P. Forquer ◽  
...  
Keyword(s):  
Combination Therapy ◽  
Acute Infection ◽  
Quinone Reductase ◽  
Infection Model ◽  
Combination Therapies ◽  
Content Type ◽  
Infection Models ◽  
Dual Site ◽  
High Parasitemia

ABSTRACTAntimalarial combination therapies play a crucial role in preventing the emergence of drug-resistantPlasmodiumparasites. Although artemisinin-based combination therapies (ACTs) comprise the majority of these formulations, inhibitors of the mitochondrial cytochromebc1complex (cytbc1) are among the few compounds that are effective for both acute antimalarial treatment and prophylaxis. There are two known sites for inhibition within cytbc1: atovaquone (ATV) blocks the quinol oxidase (Qo) site of cytbc1, while some members of the endochin-like quinolone (ELQ) family, including preclinical candidate ELQ-300, inhibit the quinone reductase (Qi) site and retain full potency against ATV-resistantPlasmodium falciparumstrains with Qosite mutations. Here, we provide the firstin vivocomparison of ATV, ELQ-300, and combination therapy consisting of ATV plus ELQ-300 (ATV:ELQ-300), usingP. yoeliimurine models of malaria. In our monotherapy assessments, we found that ATV functioned as a single-dose curative compound in suppressive tests whereas ELQ-300 demonstrated a unique cumulative dosing effect that successfully blocked recrudescence even in a high-parasitemia acute infection model. ATV:ELQ-300 therapy was highly synergistic, and the combination was curative with a single combined dose of 1 mg/kg of body weight. Compared to the ATV:proguanil (Malarone) formulation, ATV:ELQ-300 was more efficacious in multiday, acute infection models and was equally effective at blocking the emergence of ATV-resistant parasites. Ultimately, our data suggest that dual-site inhibition of cytbc1is a valuable strategy for antimalarial combination therapy and that Qisite inhibitors such as ELQ-300 represent valuable partner drugs for the clinically successful Qosite inhibitor ATV.

scholarly journals Biotechnology Applications of Cell-Free Expression Systems

Life ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1367
Author(s):  
August Brookwell ◽  
Javin P. Oza ◽  
Filippo Caschera
Keyword(s):  
Low Cost ◽  
Free Expression ◽  
Expression Systems ◽  
Genetic Circuits ◽  
Growth Cycles ◽  
Platform Technology ◽  
Near Future ◽  
Cell Free Protein Synthesis

Cell-free systems are a rapidly expanding platform technology with an important role in the engineering of biological systems. The key advantages that drive their broad adoption are increased efficiency, versatility, and low cost compared to in vivo systems. Traditionally, in vivo platforms have been used to synthesize novel and industrially relevant proteins and serve as a testbed for prototyping numerous biotechnologies such as genetic circuits and biosensors. Although in vivo platforms currently have many applications within biotechnology, they are hindered by time-constraining growth cycles, homeostatic considerations, and limited adaptability in production. Conversely, cell-free platforms are not hindered by constraints for supporting life and are therefore highly adaptable to a broad range of production and testing schemes. The advantages of cell-free platforms are being leveraged more commonly by the biotechnology community, and cell-free applications are expected to grow exponentially in the next decade. In this study, new and emerging applications of cell-free platforms, with a specific focus on cell-free protein synthesis (CFPS), will be examined. The current and near-future role of CFPS within metabolic engineering, prototyping, and biomanufacturing will be investigated as well as how the integration of machine learning is beneficial to these applications.

scholarly journals LINC00467 Promotes Tumor Progression via Regulation of the NF-kb Signal Axis in Bladder Cancer

2021 ◽  
Vol 11 ◽  
Author(s):  
Jiawei Xiao ◽  
Lian Gong ◽  
Mengqing Xiao ◽  
Dong He ◽  
Liang Xiang ◽  
...  
Keyword(s):  
Bladder Cancer ◽  
Signaling Pathway ◽  
Molecular Mechanisms ◽  
Animal Experiments ◽  
Bioinformatic Analysis ◽  
New Strategy ◽  
Patient Prognosis

PurposeLong non-coding RNAs (lncRNAs) play an important role in the occurrence and development of bladder cancer, but the underlying molecular mechanisms remain largely unknown. In this study, we found that LINC00467 was significantly highly expressed in bladder cancer through bioinformatic analysis. The present study aimed to explore the role of LINC00467 in bladder cancer and its possible underlying molecular mechanisms.MethodsThe expression of LINC00467 was obtained from GEO (GSE31189), the TCGA database, and qRT-PCR. The role of LINC00467 in bladder cancer was assessed both in vitro and in vivo. RIP, RNA pulldown, and CO-IP were used to demonstrate the potential mechanism by which LINC00467 regulates the progression of bladder cancer.ResultsThrough the analysis of GEO (GSE133624) and the TCGA database, it was found that LINC00467 was highly expressed in bladder cancer tissues and that the expression of LINC00467 was significantly negatively correlated with patient prognosis. Cell and animal experiments suggest that LINC00467 promotes the proliferation and invasion of bladder cancer cells. On the one hand, LINC00467 can directly bind to NF-kb-p65 mRNA to stabilize its expression. On the other hand, LINC00467 can directly bind to NF-kb-p65 to promote its translocation into the nucleus to activate the NF-κB signaling pathway, which promotes the progression of bladder cancer.ConclusionsLINC00467 is highly expressed in bladder cancer and can promote the progression of bladder cancer by regulating the NF-κB signaling pathway. Therefore, targeting LINC00467 is very likely to provide a new strategy for the treatment of bladder cancer and for improving patient prognosis.

scholarly journals Advances in Research on the Protective Mechanisms of Traditional Chinese Medicine (TCM) in Islet β Cells

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Na Li ◽  
Hongli Zhang ◽  
Xiaohua Li
Keyword(s):  
Chinese Medicine ◽  
Cell Function ◽  
Animal Experiments ◽  
Cell Protection ◽  
Insulin Synthesis ◽  
Treatment Of Diabetes ◽  
Insulinoma Cells

The dysfunction and decreased number of islet β cells are central to the main pathogenesis of diabetes. Improving islet β cell function and increasing the number of β cells are effective approaches to treat diabetes and constitute the main direction of diabetes drug development. The role of Chinese medicine in the treatment of diabetes began to be recognized. In recent years, Chinese medicine monomers have been found to increase insulin synthesis and secretion, reduce β cell-apoptosis, and protect the function of β cells. The results of in vivo animal experiments and in vitro studies on insulinoma cells also suggested TCMs could promote the proliferation of pancreatic islet β cells and induce other cells differentiation or transdifferentiation to islet β cells. Thereby, they may play a role in the treatment of diabetes. In this paper, we will review islet β cell protection with TCMs and the related mechanisms found in recent studies. An in-depth explanation of the role of TCM in islet β cell protection can provide a theoretical basis and research ideas for the development of TCM-based diabetes treatment drugs.

scholarly journals 1544. Efficacy of Human-Simulated Cefiderocol Exposure Against Gram-Negative Bacteria in an Iron-Overloaded Murine Thigh Infection Model

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S563-S563
Author(s):  
James M Kidd ◽  
Kamilia Abdelraouf ◽  
David P Nicolau
Keyword(s):  
Iron Overload ◽  
Host Immunity ◽  
Infection Model ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Infection Models ◽  
Student’S T ◽  
Inoculation Treatment ◽  
Student’S T Test

Abstract Background Cefiderocol (CFDC) is a siderophore-cephalosporin conjugate which exploits bacterial iron scavenging in reaction to the hypoferremic response of host immunity and achieves potent in vivo activity against various Gram-negative bacteria (GNB). In patients with hereditary or iatrogenic hemochromatosis, the hypoferremic response may be altered by iron overload, which could hypothetically suppress the bacterial iron scavenging that bolsters CFDC efficacy. We compared CFDC efficacy between iron-overloaded (Fe+) and normal iron (NFe) murine thigh infection models. Methods Female CD-1 mice received iron dextran 100 mg/kg/d for 14 d to induce iron overload (Fe+) (ASM Microbe 2019 abstract HMB-373); an equal number of same-age mice were not dosed (NFe). On day 15, both thighs of mice rendered neutropenic were inoculated with GNB suspensions of 107 CFU/mL. Twenty CFDC-susceptible isolates with previously determined CFDC MIC from 0.25 to 4 mg/L, including Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacteriales, were used. Two hours after inoculation, treatment mice were dosed with a CFDC regimen simulating the human plasma PK profile after doses of 2g q8h (3 h infusion), while control mice were sacrificed (0 h) or dosed with saline placebo on the same schedule as the CFDC regimen (24 h). All procedures were simultaneously performed in Fe+ and NFe mice. Efficacy was defined as a change in log10 CFU/thigh at 24 h vs. 0 h and was compared between Fe+ and NFe mice for individual isolates using Student’s t-test. Results Mean (SD) bacterial burdens at 0 h in Fe+ and NFe control mice were 5.77 (0.52) and 5.76 (0.52) and log10 CFU/thigh, respectively, and, at 24 h, increased by 3.49 (0.73) and 3.42 (0.96) log10 CFU/thigh, respectively. Mean (SD) efficacies of CFDC in Fe+ and NFe mice were -1.98 (0.83) and -1.98 (0.72) log10 CFU/thigh, respectively. For 17 of 20 individual isolates, no significant differences in efficacy between Fe+ and NFe mice were observed (P > 0.05); 2 of the 3 isolates with a difference had greater efficacy in Fe+ mice. Conclusion Human-simulated exposure of CFDC is equally efficacious in iron-overloaded and normal hosts against a variety of GNB susceptible to CFDC. The potential clinical use of CFDC to treat GNB infections in patients with iron overload is supported. Disclosures All authors: No reported disclosures.

scholarly journals Efficacy of Humanized Carbapenem and Ceftazidime Regimens against Enterobacteriaceae Producing OXA-48 Carbapenemase in a Murine Infection Model

2013 ◽  
Vol 58 (3) ◽  
pp. 1678-1683 ◽  
Author(s):  
Dora E. Wiskirchen ◽  
Patrice Nordmann ◽  
Jared L. Crandon ◽  
David P. Nicolau
Keyword(s):  
Wild Type Strain ◽  
Treatment Options ◽  
Infection Model ◽  
Wild Type ◽  
Content Type ◽  
Phenotypic Profile ◽  
Infection Models ◽  
The Relationship ◽  
Growth Controls

ABSTRACTEnterobacteriaceaeproducing the OXA-48 carbapenemase are emerging worldwide, leaving few treatment options. Efficacy has been demonstratedin vivowith ceftazidime against a ceftazidime-susceptible OXA-48 isolate but not with imipenem despite maintaining susceptibility. The relationship between phenotype andin vivoefficacy was assessed for OXA-48 producers using humanized regimens of 2 g doripenem every 8 h (q8h; 4 h infusion), 1 g ertapenem q24h, 2 g ceftazidime q8h (2 h inf), and 500 mg levofloxacin q24h. Each regimen was evaluated over 24 h against an isogenic pair (wild-type and OXA-48Klebsiella pneumoniaestrains) and six clinical OXA-48 isolates with and without other extended-spectrum β-lactamases in immunocompetent and neutropenic murine thigh infection models. Efficacy was determined using the change in bacterial density versus 24-h growth controls in immunocompetent studies and 0-h controls in neutropenic studies. Bacterial reductions of ≥1 log CFU were observed with all agents for the wild-type strain. Consistent with low MICs, ceftazidime and levofloxacin exhibited efficacy against the isogenic OXA-48 strain, whereas doripenem did not, despite having a susceptible MIC; no activity was observed with ertapenem, consistent with a resistant MIC. Similar trends were observed for the clinical isolates evaluated. Ceftazidime, levofloxacin, and ertapenem efficacy against isogenic and clinical OXA-48-producing strains correlated well with phenotypic profiles and pharmacodynamic targets, whereas efficacy with doripenem was variable over the MIC range studied. These data suggest that carbapenems may not be a reliable treatment for treating OXA-48 producers and add to previous observations with KPC and NDM-1 suggesting that genotype may better predict activity of the carbapenems than the phenotypic profile.

Sign in / Sign up

Export Citation Format

Share Document