Surface display of Gaussia princeps luciferase allows sensitive fungal pathogen detection during cutaneous aspergillosis

Abstract

Non-invasive imaging techniques in microbial disease models have delivered valuable insights in the intimate pathogen-host interplay during infection. Here we describe evaluation and validation of a transgenic bioluminescence reporter strain of the human-pathogenic mold Aspergillus fumigatus, one of the main fungal pathogens affecting immunocompromised individuals. Expression and surface display of the Gaussia princeps luciferase allowed sensitive and rapid detection of luminescence emitted from this strain after substrate addition, with photon fluxes strongly correlating to the amounts of fungal conidia or germlings. The reporter strain allowed spatio-temporal monitoring of infection in a cutaneous model of aspergillosis, where neutropenic mice maintained the fungal burden while immunocompetent ones were able to clear it entirely. Most importantly, antifungal therapy could be followed in this type of disease model making use of the bioluminescent A. fumigatus strain. In conclusion, combining sensitivity of the Gaussia luciferase with a surface display expression system in the fungal host allows longitudinal infection studies on cutaneous forms of aspergillosis, providing perspective on drug screening approaches at high-throughput.

Keywords: :

• Aspergillus fumigatus
• antifungal therapy
• bioluminescence
• biophotonic imaging
• cutaneous aspergillosis

Disclosure of Potential Conflict of Interest

No potential conflicts of interest were disclosed.

Acknowledgments

We are indebted to Astrid Dylda, Axelle Degla, and Michaela Dümig for excellent technical assistance and to all other members of the Institute for Molecular Infection Biology for continuous support. Werner J. Heinz is thanked for providing posaconazole, Thomas Hartmann for qPCR analyses, Hilde Merkert for providing assistance with fluorescence microscopy, and Christian Erck from the HZI Braunschweig, Germany for typing the monoclonal α-GLuc antibody. Funding was received from the German José Carreras Leukaemia Foundation (Cooperation Project DJCLS 10/15), the Free State of Bavaria, and the University of Würzburg.