Identification and analysis of enriched proteins on the conidial surface of the human pathogenic fungus Aspergillus fumigatus

Abstract

The section Fumigati is composed by Aspergillus fungal strains presenting variable pathogenicity levels. Within this section, Aspergillus fumigatus, an opportunistic pathogen, is responsible for approximately 70% of cases of invasive pulmonary aspergillosis (IPA) presenting the highest pathogenicity rates. Some data have demonstrated that for A. fumigatus, the ability to grow at high temperatures and under nutrient-limiting conditions, in addition to the ability to produce secondary metabolites, favor its pathogenicity and help the survival inside the human host.The API is established after inhalation of infectious fungal propagules produced asexually by Aspergillus and called conidia. These propagules are found dispersed in the environment and can eventually be inhaled by the human host. In healthy individuals, conidia are promptly cleared by the innate immune system. However, in patients with immune dysfunctions or preexisting pulmonary conditions, conidium clearance may fail, culminating culminating with the development of IPA. Thus, the conidia are the first point of contact between the fungus and human cells (of the lung epithelium and the immune system) and, therefore, are extremely important for the progression (or not) of the disease. Furthermore, the ability to produce large quantities of conidia seems to be a differentiating and crucial factor for the success of infection by A. fumigatus. Regarding composition, the conidia surface is mainly composed of proteins, sugars, and secondary metabolites. Some studies have explored the analysis of the saccharide composition of the conidial surface. However, little is known about the protein composition of these cells.The current project is based on a previous study that determined the set of proteins present exclusively on the surface of A. fumigatus conidia, which were identified in a comparative way with 3 other Aspergillus species from the Fumigati section, two not frequently related to API (A. oerlinghausenensis and A. fischeri) and A. lentulus. From 62 proteins enriched on the conidial surface of A. fumigatus, 42 had their respective genes deleted and, to date, these mutant strains have been partially characterized in vitro and in vitro. To expand the knowledge generated previously, the current proposal will focus on the proteomic analysis of the conidial surface from A. fumigatus and A. fischeri by using the trypsin-shaving methodology followed by mass spectrometry. As a difference, 10 new fungal strains will be included in the study, being 5 clinical isolates of A. fumigatus and 5 environmental strains of A. fischeri. The data obtained will be compared to identify the set of proteins specifically enriched on the surface of conidia cells of A. fumigatus. This approach aims to identify peptides that constitute the set of proteins enriched on the surface of A. fumigatus conidia and confirm that the set of proteins enriched occurs among several clinical isolates of the species, and not only in the reference strain used in previously performed assays. (AU)