Adiaspore development and morphological characteristics in a mouse adiaspiromycosis model

Abstract

Lesions of adiaspiromycosis, a respiratory disease affecting wild animals, have been found mainly in dead mammals and free-living mammals captured for surveillance. No report has described an investigation of adiaspore formation progress in the lung. After establishing an experimental mouse model of intratracheal adiaspiromycosis infection with the causative agent Emmonsia crescens, we observed adiaspore development. The spores grew and reached a plateau of growth at 70 days post-infection. The median adiaspore diameter showed a plateau of around 40 μm. The characteristic three-layer cell-wall structure of adiaspores was observed in the lung at 70 days post-infection. We examined infection with a few spores, which revealed that adiaspores in the mouse lung progressed from intratracheal infection of at least 400 spores. Moreover, we developed adiaspores in vitro by culture in fetal bovine serum. Although most spores broke, some large spores were intact. They reached about 50 μm diameter. Thick cell walls and dense granules were found as common points between in vitro adiaspores and in vivo adiaspores. These models are expected to be useful for additional investigations of E. crescens adiaspores and adiaspiromycosis.

Pathological Findings in Eurasian Otters (Lutra lutra) Found Dead between 2015−2020 in Schleswig-Holstein, Germany

“…Bronchopneumonia was seen in two males of an unknown age, in one case together with intralesional fungal spores ( Figure 4 ). An additional female (2.5–4.5 years) likewise showed bronchopneumonia with intralesional structures suggesting adiaspores [ 55 ]. Using a broadrange PCR assay fungal DNA of the typical agent of Adiaspiromycosis, Adiaspiromyces could not be amplified, probably due to inhibition of the PCR, a frequent problem in formalin-fixed and paraffin-embedded tissue, and the presence of other fungal DNA from different potentially contaminating fungi.…”