P384 Characterization of the virulence potential of Aspergillus species of section Terrei in Galleria mellonella infection model

Abstract Poster session 3, September 23, 2022, 12:30 PM - 1:30 PM Objectives Species belonging to the genus of Aspergillus are among the most common causative agents of human and animal infections. Less than 40 species among all Aspergillus species are known to be associated with human infections, including allergic bronchopulmonary aspergillosis, chronic pulmonary aspergillosis, and invasive aspergillosis. And of these, Aspergillus section Fumigati is one of the major infectious causes of death, followed by members of sections Flavi, Nigri, and Terrei. Aspergillus species in section Terrei are categorized into three series: Ambigui, Nivei, and Terrei. A. terreus sensu stricto is the first species described and the most common species found worldwide in different ecological habitats. However, there are several other species within the section Terrei, stating cryptic species which are not distinguished by conventional morphological analysis, even though they are taxonomically accepted by forming a distinctive phylogenetic clade. Despite definitive species identification, there is still less known about the virulence potential of all species in this section, and it might be underestimated because of their lack of distinction by conventional diagnostic methods. In this ongoing study, the in vivo Galleria mellonella model has been utilized to examine the inter-and/or intraspecies virulence dependency of section Terrei. Methods A total of 18 accepted Aspergillus species in section Terrei (n = 18) were tested, including A. terreus sensu stricto, A. citrinoterreus, A. hortae, A. pseudoterreus, A. alabamensis, A. aureoterreus, A. floccosus, A. iranicus, A. recifensis, A. carneus, A. microcysticus, A. niveus, A. bicephalus, A. neoindicus, A. neoafricanus, A. barbosae, A. ambiguus, and A. allahabadii. Species were identified by sequencing gene regions of b-tubulin, calmodulin, and RNA Polymerase II Subunit 2 (RPB2). Briefly, groups of larvae (n = 30) (0.3 to 0.4 g; SAGIP, Italy) were stored in wood shavings in the dark at 18°C for 24 h before the experiment. Three groups were included: larvae infected with 107 conidia/larva, larvae injected with 20 μL sterile insect physiological saline, and untouched larvae. The survival rate was monitored for up to 144 h at 37°C. Results Median survival rates revealed a species-dependent virulence pattern. Larvae inoculated with A. aureoterreus, A. pseudoterreus (Serie Terrei) and A. niveus, A. carneus, and A. iranicus (Serie Nivei) exhibited high virulence potential by reflecting lower survival rates in comparison with other species. In contrast, species belonging to the series Ambigui showed low virulence potential. Conclusion In conclusion, the virulence characteristics of section Terrei differ between species. Further studies are needed to unravel the species' invasiveness, such as histopathology and immune response of G. mellonella.