Aspergillus fumigatus hyphal branching mutant shows enhanced susceptibility to host defenses and caspofungin in vivo

Author:

TJ Schoen1,2*, DG Calise1,3, M Niu1, JW Bok1, A Huttenlocher1,4, NP Keller1,5

Author address:

1Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, USA

2Comparative Biomedical Sciences Graduate Program, University of Wisconsin-Madison, Madison, USA

3Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, USA

4Department of Pediatrics, University of Wisconsin-Madison, Madison , USA

5Department of Bacteriology , University of Wisconsin-Madison, Madison, USA

Full conference title:

10th Advances Against Aspergillosis and Mucormycosis

Date: 2 February 2022

Abstract:

Purpose:

The efficacy of echinocandins for invasive aspergillosis treatment is marred by the ability of Aspergillus to mount compensatory alterations in cell wall integrity and stress response signaling. The transcription factor ZfpA regulates features of A. fumigatus growth reminiscent of echinocandin tolerance mechanisms, including hyphal branching, septa formation, and cell wall composition. However, the relevance of ZfpA-mediated changes to fungal growth and stress resistance during infection is unclear. We hypothesize that ZfpA regulation of fungal growth and critical stress response pathways shapes fungal interaction with immune cells and echinocandin tolerance in vivo, and therefore represents a valuable target for improving aspergillosis therapies.

 

Methods:

We coupled the optical transparency of larval zebrafish with RFP-expressing wild-type, ZfpA deletion (ΔzfpA), and overexpression (OE:zfpA) strains to track fungal development, immune cell recruitment, and host survival during A. fumigatus (CEA10 genetic background) infection.

 

Results:

Previous in vitro analyses of ZfpA manipulation describe decreased hyphal branching and chitin content in ZfpA deletion mutants, while ZfpA overexpression increases both branching and chitin.Here, we demonstrate a novel role for ZfpA in disease progression and susceptibility to caspofungin in vivo. In a wild-type host, ZfpA deletion does not alter germination or leukocyte recruitment but does reduce fungal burden and attenuate virulence of A. fumigatus in later stages of infection. Virulence of ΔzfpA is re-established in a neutropenic host, suggesting enhanced susceptibility of ΔzfpA to neutrophil killing. Overexpression of ZfpA does not alter germination, fungal burden, leukocyte recruitment, or virulence in wild-type or neutropenic hosts. Concomitant with our in vitro analyses of capsofungin tolerance, caspofungin treatment improves survival of animals infected with ΔzfpA but has no effect on survival of OE:zfpA-infected animals, indicating enhanced caspofungin sensitivity of ΔzfpA and decreased sensitivity of OE:zfpA in vivo.

 

Conclusion:

Our study identifies ZfpA as a regulator of resistance to host defenses and caspofungin treatment during infection.

Abstract Number: 81

Conference Year: 2022

Link to conference website: https://aaam2022.org/

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