Galleria mellonellaas a host model to studyAspergillus terreusvirulence and amphotericin B resistance

Abstract

Keywords: amphotericin B resistant and susceptible A. terreus strain cluster, Galleria mellonella, invertebrate in vivo modelThe aim of this study was to investigate if the alternative in vivo model Galleria mellonella can be used (i) to determine differences in pathogenicity of amphotericin B (AMB) resistant and susceptible A. terreus isolates, (ii) to evaluate AMB efficacy in vivo (iii) and to correlate outcome to in vitro susceptibility data. Larvae were infected with 2 A. terreus AMB resistant (ATR) and 3 AMB susceptible (ATS) isolates and survival rates were correlated to physiological attributes and killing ability of larval haemocytes. Additionally, infected larvae were treated with different concentrations of L-AMB. Haemocyte density were ascertained to evaluate the influence of L-AMB on the larval immune cells. Larvae were sensitive to A. terreus infection in an inoculum-size and temperature dependent manner. In vitro susceptibility to L-AMB correlated with in vivo outcome of antifungal treatment, defining an AMB susceptible strain cluster of A. terreus. Susceptibility to L-AMB increased virulence potential in the larval model, but this increase was also in accordance with faster growth and less damage caused by larval haemocytes. L-AMB treatment primed the larval immune response by increasing haemocyte density. G. mellonella provides a convenient model for the in vivo screening of A. terreus virulence and treatment options, contributing to the generation of a hypothesis that can be further tested in refined experiments in mammalian models.

Cryptic species of Aspergillus section Terrei display essential physiological features to cause infection and are similar in their virulence potential in Galleria mellonella

“…Germination rates of phialidic conidia (= spores) were determined for each isolate after 8 h of incubation at 30°C (body surface temperature) and 37°C (body core temperature) ( Table 2). At that time point, the percentage of spores showing germ tube formation were higher at 37°C, which correlates to what has been previously reported [31]. Highest rate of spores with germ tubes was detected for A. citrinoterreus (56.6% ± SD 2.2).…”

N -Chlorotaurine Exhibits Fungicidal Activity against Therapy-Refractory Scedosporium Species and Lomentospora prolificans

“…Suspensions of pure conidia were gained by harvesting them from the agar plates with 5.0 ml of 0.9% saline plus 0.01% Tween 20 after growth for 8 to 10 weeks, followed by 10-m filtration (CellTrics; Partec GmbH, Görlitz, Germany) (26). For tests using the Galleria mellonella in vivo model (see below), conidia grown and harvested from Scedosporium selective agar (SceSelϩ [27]) were ultrasonicated for 10 min in the Sonorex RK 102 apparatus, followed by 40-m filtration (Falcon cell strainer; Corning, Inc., NY) and then 10-m (CellTrics) filtration.…”

Arginine Auxotrophy Affects Siderophore Biosynthesis and Attenuates Virulence of Aspergillus fumigatus

“…Virulence studies in G. mellonella were carried out according to Maurer et al [35]. Before use, sixth instar larvae, weighing between 0.4 and 0.5 g (SAGIP, Bagnacavallo, Italy), were kept in the dark at 18 • C. Then, 1 × 10 7 freshly harvested A. fumigatus spores were suspended in 20 µL of insect physiological saline (IPS) and injected into the hemocoel via one of the hind pro-legs.…”