Characterising Tenebrio molitor, mealworm, as a host for studying Aspergillus fumigatus pathogenesis

Abstract

Aspergillus fumigatus is an opportunistic fungal pathogen that is the leading cause of Invasive Aspergillosis (IA). Despite the availability of diagnostics and treatments, IA has high morbidity and mortality ranging from 30-95%. This is due to the complexity of infection as virulence depends on interactions that occur between fungal traits and host immunity. Model organisms can be utilised to investigate these interactions including invertebrates as they utilise innate immunity, which when impaired in humans represents an important IA risk factor. In this project, Tenebrio molitor larvae were explored as an alternative invertebrate to study A. fumigatus pathogenesis. Several methods were utilised to characterise infection. This includes colony forming unit (CFU) counts and quantitative polymerase chain reaction (qPCR) to quantify infection over time. To visualise infection, histological examination and magnetic resonance imaging (MRI) were utilised, and haemocyte interaction assays to examine haemocyte-fungal interactions in detail. Inoculation of T. molitor larvae with A. fumigatus was observed to decrease survival over time, increase the fungal burden, and cause the presence of nodules within larval tissue. These nodules were accompanied by cells suspected to be haemocytes, which during interaction assays became activated upon exposure to A. fumigatus conidia. Similar observations have been observed in other invertebrates including Galleria mellonella. T. molitor larvae may thus be useful to study A. fumigatus pathogenesis, however further optimisations of these methods are necessary to confirm these findings and characterise infection, such as utilisation of fungal specific stains and additional methodologies including confocal microscopy and flow cytometry to assess phagocytosis.

Date of Award	2022
Original language	English