Powerful and Real-Time Quantification of Antifungal Efficacy against Triazole-Resistant and -Susceptible Aspergillus fumigatus Infections in Galleria mellonella by Longitudinal Bioluminescence Imaging

Abstract

Triazole-resistant Aspergillus fumigatus strains are rapidly emerging, and resistant infections are difficult to treat, causing mortality rates of up to 88%. The recent WHO priority list underscores A. fumigatus as one of the most critical fungal pathogens for which innovative antifungal treatment should be (urgently) prioritized.

Sensitive bioluminescence imaging of cryptococcosis in Galleria mellonella improves antifungal screening under in vivo conditions

“…The BLI signal was read using an IVIS Spectrum (PerkinElmer, USA) imaging system by acquiring five consecutive images with an exposure time of 30 s (open filter, F/stop1, subject height 0.5 cm, medium binning). Living Image Software (version 4.5.4, PerkinElmer, USA) was used to define regions of interest (ROI) covering each individual well and to calculate the total photon flux (p/s) per well, and peak total fluxes were used for analysis and comparison [ 27 ].…”

“…Therefore, the study of cryptococcosis in G. mellonella would benefit from a novel readout of fungal burden that is quantitatively correct but also non-invasive, allowing direct longitudinal follow-up of cryptococcal infection and treatment effects over time, independent of overall larval health state and off-target toxicity. Recently, we optimized bioluminescence imaging (BLI) for real-time quantitative readout of Aspergillus fumigatus , a filamentous fungus, in G. mellonella [ 27 ]. Similarly, BLI has the potential to be implemented as a fungal readout in G. mellonella for yeasts, such as C. neoformans.…”

Galleria mellonella as a Model for the Study of Fungal Pathogens: Advantages and Disadvantages

“…G. mellonella has been used to study many fungi, including Aspergillus spp., Candida spp., Cryptococcus spp., Conidiobolus coronatus , Histoplasma capsulatum , Madurella mycetomatis , Malassezia spp. and Paraccocidioides brasiliensis [ 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 ].…”

“…Categorising studies using G. mellonella larvae to assess virulence or drug efficacy is a challenging task. It is more appropriate to evaluate the work based on different fungal genera since some species have undergone extensive research in recent years [ 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 ].…”

“…The authors show that bioluminescence imaging is a more reliable, sensitive and quicker method for quantifying fungal load. This method can not only detect the treatment effects for both susceptible and triazole-resistant infections, but it can also improve the translatability of in vitro antifungal screening results to in vivo confirmation in mouse and human studies [ 93 ].…”