Interaction of Talaromyces marneffei with free living soil amoeba as a model of fungal pathogenesis

Abstract

Talaromyces (Penicillium) marneffei is an important dimorphic mycosis endemic in Southeast Asia and Southern China, but the origin and maintenance of virulence traits in this organism remains obscure. Several pathogenic fungi, including Cryptococcus neoformans, Aspergillus fumigatus, Blastomyces dermatitidis, Sporothrix schenckii, Histoplasma capsulatum and Paracoccidioides spp. interact with free living soil amoebae and data suggests that fungal pathogenic strategies may emerge from environmental interactions of these fungi with ubiquitous phagocytic microorganisms. In this study, we examined the interactions of T. marneffei with the soil amoeba Acanthamoeba castellanii. T. marneffei was rapidly ingested by A. castellanii and phagocytosis of fungal cells resulted in amoeba death after 24 h of contact. Co-culture also resulted in a rapid transition for conidia to the fission-yeast form. In addition, well-established virulence factors such as melanin and a yeast specific mannoprotein of T. marneffei were expressed during interaction with A. castellanii at 37°C. Our findings support the assumption that soil amoebae environmental predators play a role in the selection and maintenance of particular features in T. marneffei that impart virulence to this clinically important dimorphic fungus in mammalian hosts.

Adaptation to an amoeba host drives selection of virulence-associated traits and genetic variation in saprotrophic Candida albicans

“…Amoebae were collected by tapping the flasks, centrifuged at 3,000 rpm for 10 minutes, and suspended in sterile phosphate buffer saline (1× PBS, pH 7.2). The cells were counted using a modified Fuchs-Rosenthal chamber, and viability was evaluated by trypan blue staining ( Pruksaphon et al., 2022 ). The initial viability was always greater than 98% (data not shown).…”

“…The yeast cells were then subjected to a 10-fold dilution. The viability of yeast cells was assessed by spreading them on SDA and incubating at 28°C for 24 hours, determined by the colony-forming units (CFU)/mL count and calculated as direct determination of the cell viability ( Pruksaphon et al., 2022 ).…”