Project description:Candida auris is an emerging infectious agent and WHO critical priority fungal pathogen. Rising pan-resistance, massive nosocomial outbreaks and diagnostic challenges complicate clinical treatment, with an associated human mortality rate of 45%. Importantly, in vivo gene expression of C. auris during infection has not been described to date. We developed the novel thermotolerant teleost fish embryo yolk-sac microinjection model of Aphanius dispar (Arabian Killifish, AK) for infection by each of the five major C. auris clades. This model enabled dual host-pathogen RNA-seq at 24 and 48 hours post injection (HPI) at mammalian temperature (37 °C), which has not been reported in other teleost fish models. Host gene expression indicated features of nutritional and innate immune responses, including haem-oxygenase and C-type lectin receptor expression. We identified an in vivo transcriptome signature common to all five clades of C. auris compared to in vitro expression that was highly enriched for putative xenosiderophore transmembrane transporters. We describe the seventeen-member xenosiderophore transport candidate family in terms of diverse in-host patterns of expression and cross-kingdom functional prediction. We discovered that only the basal clade V isolate formed filaments in vivo, corresponding with Candida-typical and atypical hypha-formation genetic signals, such as the novel adhesin SCF1. Furthermore, clades that were more virulent (I or IV vs II or III) were strongly characterised by upregulation of the majority of genes at the mating-type locus (MTL), including non-mating genes, consistent with a role for the MTL in C. auris pathogenicity. We hypothesise that both xenosiderophore transport genes and the MTL may play critical roles in C. auris virulence, and are urgent targets for potential therapy.
Project description:The emergence of Candida auris poses a significant health challenge that has led to a new era of multidrug-resistant fungal infections. Invasive infections caused by C. auris are usually associated with remarkable morbidity and mortality. For many years, amphotericin B (AmB) remained the most efficient and the last line of treatment against most hard-to-treat fungal infections. However, strains of C. auris possess extraordinary resistance to most antifungal agents, including AmB. In this study, we screened ~2600 FDA-approved drugs and clinical compounds to identify the antiemetic drug rolapitant as a promising enhancer to AmB against C. auris. Rolapitant exhibited potent synergistic interactions with AmB against all tested (29/29) C. auris isolates. In a time-kill assay, rolapitant restored the fungicidal activity of AmB within 4 h. Additionally, the synergistic relationship between rolapitant and AmB was observed against other medically crucial Candida, Cryptococcus and Aspergillus species with ΣFICI that ranged from 0.16 to 0.5. In a transcriptomic study, ion transporters and ATP generation were identified as primary pathways impacted in C. auris AR0390 cells exposed to rolapitant. An ATP luminescence assay confirmed that rolapitant, at sub-inhibitory concentrations, significantly interfered with ATP production in C. auris. Moreover, rolapitant enhanced the in vivo activity of AmB in a mouse model of disseminated C. auris infection, as the combination reduced the fungal burden in murine kidneys by ~1 log (~90%) colony forming units. Our findings warrant further investigation of using rolapitant to overcome AmB resistance in C. auris and other fungal species.
