Fungal hydrophobins form a sheath preventing immune recognition of airborne conidia

Area of Science:

• Medical Mycology
• Immunology
• Microbial Pathogenesis

Background:

• Aspergillus fumigatus is a ubiquitous airborne fungal pathogen.
• Inhaled fungal conidia must evade innate immune defenses to survive in the host.
• The mechanisms by which A. fumigatus conidia resist host defenses remain incompletely understood.

Purpose of the Study:

• To investigate the role of the spore-surface rodlet layer in A. fumigatus immune evasion.
• To determine if the rodlet layer is essential for fungal survival in vivo.

Main Methods:

• Chemical, genetic, and biological methods were used to remove the A. fumigatus spore-surface rodlet layer.
• The immunogenicity of modified A. fumigatus morphotypes was assessed.
• Fungal survival in vivo was evaluated.

Main Results:

• The rodlet layer is composed of hydrophobic proteins (hydrophobins).
• Removal of the rodlet layer resulted in immunostimulatory fungal morphotypes.
• The rodlet layer is essential for A. fumigatus survival in vivo.

Conclusions:

• The spore-surface rodlet layer is critical for preventing immune recognition of Aspergillus fumigatus.
• This layer plays an essential role in the survival of A. fumigatus conidia within the host.