Galleria mellonella as a Model for Fungal Pathogenicity Testing

Fallon, John P.; Kelly, Judy; Kavanagh, Kevin

doi:10.1007/978-1-61779-539-8_33

Cited by 80 publications

(78 citation statements)

References 16 publications

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“…Importantly, current matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) approaches are apparently unable to robustly distinguish C. africana and C. albicans (see, for example, Bruker Daltonik TechNote 1.0; Bruker Daltonik GmbH, Bremen, Germany). Given the reduced formation of hyphae and slower growth of C. africana compared to C. albicans, as well as previous reports demonstrating that C. dubliniensis exhibits reduced pathogenicity compared to C. albicans in a variety of infection models (reviewed in references 15 and 14), we compared the virulence of isolates of C. albicans, C. africana, and C. dubliniensis in a systemic infection model using the insect larval model Galleria mellonella (34)(35)(36)(37). Although recent studies have failed to reveal differences in pathogenicity between mucosal and systemic isolates of key pathogenic yeast species in Galleria larvae (40), any such potential bias in the current study was avoided by comparing C. africana strains with C. albicans and C. dubliniensis isolates that had also been recovered from female genital samples.…”

Section: Resultsmentioning

confidence: 99%

“…Killing assays were performed in Galleria mellonella essentially as described previously (34)(35)(36)(37). Briefly, final (sixth) instar larvae weighing approximately 300 mg each (Livefood UK Ltd., Rooks Bridge, Somerset, United Kingdom) that were absent of gray markings were maintained at room temperature in the dark and inoculated within 1 week of receipt.…”

Section: Methodsmentioning

confidence: 99%

“…Control groups of larvae received 10 l of sterile PBS in exactly the same manner. Inoculated larvae were incubated at 30°C, 37°C, or 42°C and scored for viability at 8-h intervals as described previously (34)(35)(36)(37). Differences in resulting Kaplan-Meier survival plots were evaluated using the Mann-Whitney (two-sample Wilcoxon) test.…”

Section: Methodsmentioning

confidence: 99%

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Epidemiology, Antifungal Susceptibility, and Pathogenicity of Candida africana Isolates from the United Kingdom

Borman¹,

Székely²,

Linton³

et al. 2013

J Clin Microbiol

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Candida africana was previously proposed as a new species within the Candida albicans species complex, together with C. albicans and C. dubliniensis, although further phylogenetic analyses better support its status as an unusual variant within C. albicans. Here we show that C. africana can be distinguished from C. albicans and C. dubliniensis by pyrosequencing of a short region of ITS2, and we have evaluated its occurrence in clinical samples by pyrosequencing all presumptive isolates of C. albicans submitted to the Mycology Reference Laboratory over a 9-month period. The C. albicans complex constituted 826/1,839 (44.9%) of yeast isolates received over the study period and included 783 isolates of C. albicans, 28 isolates of C. dubliniensis, and 15 isolates of C. africana. In agreement with previous reports, C. africana was isolated exclusively from genital specimens, in women in the 18-to-35-year age group. Indeed, C. africana constituted 15/251 (6%) of "C. albicans" isolates from female genital specimens during the study period. C. africana isolates were germ tube positive, grew significantly more slowly than C. albicans and C. dubliniensis on conventional mycological media, could be distinguished from the other members of the C. albicans complex by appearance on chromogenic agar, and were incapable of forming chlamydospores. Here we present the detailed evaluation of epidemiological, phenotypic, and clinical features and antifungal susceptibility profiles of United Kingdom isolates of C. africana. Furthermore, we demonstrate that C. africana is significantly less pathogenic than C. albicans and C. dubliniensis in the Galleria mellonella insect systemic infection model.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Epidemiology, Antifungal Susceptibility, and Pathogenicity of Candida africana Isolates from the United Kingdom

Borman¹,

Székely²,

Linton³

et al. 2013

J Clin Microbiol

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“…26,59,60 G. mellonella larvae of a similar size were selected (approximately 275-330 mg) and kept without food in petri dishes, at 37 C, in darkness for 24 h prior to use. …”

Section: Animal Modelsmentioning

confidence: 99%

The development of animal infection models and antifungal efficacy assays against clinical isolates ofTrichosporon asahii,T. asteroidesandT. inkin

et al. 2015

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The present study developed Galleria mellonella and murine infection models for the study of Trichosporon infections. The utility of the developed animal models was demonstrated through the assessment of virulence and antifungal efficacy for 7 clinical isolates of Trichosporon asahii, T. asteroides and T. inkin. The susceptibility of the Trichosporon isolates to several common antifungal drugs was tested in vitro using the broth microdilution and the Etest methods. The E-test method depicted a lower minimal inhibitory concentration (MIC) for amphotericin and a slightly higher MIC for caspofungin, while MICs observed for the azoles were different but comparable between both methods. All three Trichosporon species established infection in both the G. mellonella and immunosuppressed murine models. Species and strain dependent differences were observed in both the G. mellonella and murine models. T. asahii was demonstrated to be more virulent than the other 2 species in both animal hosts. Significant differences in virulence were observed between strains for T. asteroides in the murine model. In both animal models, fluconazole and voriconazole were able to improve the survival of the animals compared to the untreated control groups infected with any of the 3 Trichosporon species. In G. mellonella, amphotericin was not able to reduce mortality in any of the 3 species. In contrast, amphotericin was able to reduce murine mortality in the T. asahii or T. inkin models, respectively. Hence, the developed animal infection models can be directly applicable to the future deeper investigation of the molecular determinants of Trichosporon virulence and antifungal resistance.

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“…Sixth-instar-stage G. mellonella larvae were injected through the last proleg with 5 ϫ10 6 A. fumigatus conidia, which had been suspended in 10 l of phosphatebuffered saline (PBS) as previously described (23). The larvae were kept for 8 days at 37°C, and death was monitored by visual inspection and prodding with a toothpick.…”

mentioning

confidence: 99%

Identification and Characterization of a Novel Aspergillus fumigatus Rhomboid Family Putative Protease, RbdA, Involved in Hypoxia Sensing and Virulence

et al. 2016

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dAspergillus fumigatus is the most common pathogenic mold infecting humans and a significant cause of morbidity and mortality in immunocompromised patients. In invasive pulmonary aspergillosis, A. fumigatus spores are inhaled into the lungs, undergoing germination and invasive hyphal growth. The fungus occludes and disrupts the blood vessels, leading to hypoxia and eventual tissue necrosis. The ability of this mold to adapt to hypoxia is regulated in part by the sterol regulatory element binding protein (SREBP) SrbA and the DscA to DscD Golgi E3 ligase complex critical for SREBP activation by proteolytic cleavage. Loss of the genes encoding these proteins results in avirulence. To identify novel regulators of hypoxia sensing, we screened the Neurospora crassa gene deletion library under hypoxia and identified a novel rhomboid family protease essential for hypoxic growth. Deletion of the A. fumigatus rhomboid homolog rbdA resulted in an inability to grow under hypoxia, hypersensitivity to CoCl 2 , nikkomycin Z, fluconazole, and ferrozine, abnormal swollen tip morphology, and transcriptional dysregulation-accurately phenocopying deletion of srbA. In vivo, rbdA deletion resulted in increased sensitivity to phagocytic killing, a reduced inflammatory Th1 and Th17 response, and strongly attenuated virulence. Phenotypic rescue of the ⌬rbdA mutant was achieved by expression and nuclear localization of the N terminus of SrbA, including its HLH domain, further indicating that RbdA and SrbA act in the same signaling pathway. In summary, we have identified RbdA, a novel putative rhomboid family protease in A. fumigatus that mediates hypoxia adaptation and fungal virulence and that is likely linked to SrbA cleavage and activation.T he filamentous fungus Aspergillus fumigatus grows as an environmental saprophyte but can infect humans and animals through its dispersed asexual conidia. Upon inhalation by an immunocompromised host, conidia can germinate to form hyphae which infiltrate the surrounding lung tissue, causing often fatal invasive aspergillosis (IA). It is estimated that worldwide, more than 200,000 individuals suffer from life-threatening IA, with mortality rates ranging between 30 to 95% (1). These alarming statistics are a result of the generally poor health status of the patients, limited diagnostic and therapeutic options, and the arsenal of virulence-promoting properties of this ubiquitous mold (2, 3). Besides the abilities of the fungus to produce potent mycotoxins and to escape from the host innate immune cells, thermophilic growth and versatile nutrient acquisition are further general physiological attributes which favor growth on decaying matter as well as in the human host (4, 5). Adaptation to O 2 concentrations below normal atmospheric levels of 21% is an additional challenge that A. fumigatus must cope with during colonization. O 2 levels can drop to 2 to 4% on the surface of healthy alveolar tissue and be further diminished to less than 1% upon inflammation (6). Such levels of hypoxia are normally no th...

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Galleria mellonella as a Model for Fungal Pathogenicity Testing

Cited by 80 publications

References 16 publications

Epidemiology, Antifungal Susceptibility, and Pathogenicity of Candida africana Isolates from the United Kingdom

Epidemiology, Antifungal Susceptibility, and Pathogenicity of Candida africana Isolates from the United Kingdom

The development of animal infection models and antifungal efficacy assays against clinical isolates ofTrichosporon asahii,T. asteroidesandT. inkin

Identification and Characterization of a Novel Aspergillus fumigatus Rhomboid Family Putative Protease, RbdA, Involved in Hypoxia Sensing and Virulence

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