Immunoproteomic Identification of Scedosporium boydii Antigens with Potential Diagnostic Interest in Cystic Fibrosis Patients

Fungal infections caused by Scedosporium/Lomentospora species are a significant threat to patients with cystic fibrosis (pwCF), ranking as the second most common filamentous fungi in their airways after Aspergillus. Current serodiagnostic methods, such as counterimmunoelectrophoresis and ELISA using crude extracts, lack standardization and commercial availability and often show cross-reactivity with other fungi. This study aimed to identify specific Scedosporium boydii antigens with potential for serodiagnosis in pwCF. An immunoproteomic approach combining two-dimensional polyacrylamide gel electrophoresis, Western blot, and mass spectrometry was used to analyze the antigenic profile of S. boydii against sera from pwCF with positive cultures for Scedosporium/Lomentospora (Scedo+) and mice intravenously infected with these fungi. We identified 22 proteins specifically recognized by sera from pwCF Scedo+ and mice infected with S. boydii, but not by sera from pwCF or mice infected with Aspergillus spp. or uninfected controls. These proteins are primarily involved in metabolism and exhibit catalytic activity. The most prevalent antigens were the heat shock protein 70, 6-phosphogluconate dehydrogenase, 3-ketoacyl-CoA thiolase, and phosphoenolpyruvate carboxykinase, recognized by 67-81% of pwCF Scedo + sera with minimal cross-reactivity to negative samples. This work identifies promising candidates for the specific serodiagnosis of Scedosporium/Lomentospora infections in pwCF. Data are available via ProteomeXchange (PXD053392).