Development of a Highly Sensitive β-Glucan Detection System Using Scanning Single-Molecule Counting Method

Area of Science:

• Mycology
• Biotechnology
• Medical Diagnostics

Background:

• The Limulus amebocyte lysate (LAL) assay is widely used for diagnosing invasive fungal infections but suffers from limitations, including cross-reactivity with plant-derived glucans, leading to false positives.
• Accurate and reliable detection of fungal infections is crucial for timely and effective patient treatment.

Purpose of the Study:

• To develop a novel diagnostic method for invasive fungal infections that overcomes the limitations of the LAL assay.
• To evaluate a new detection system combining recombinant β-glucan binding proteins with scanning single-molecule counting (SSMC).

Main Methods:

• Preparation of a novel (1→3)-β-D-glucan recognition protein (S-BGRP) and a (1→6)-β-glucanase mutant protein.
• Testing the binding affinity of these recombinant proteins to fungal β-glucans from *Candida* and *Aspergillus* species.
• Utilizing the scanning single-molecule counting (SSMC) method for sensitive detection of β-glucan levels.

Main Results:

• The S-BGRP and mutant protein demonstrated specific binding to fungal β-glucans.
• The SSMC method showed significantly reduced sensitivity to plant-derived (1→3)-β-D-glucan compared to the LAL assay.
• This reduction in cross-reactivity minimizes false positives, a known issue with the LAL method.

Conclusions:

• The developed detection system using recombinant β-glucan-binding proteins and SSMC is a promising alternative to the LAL assay for diagnosing fungal infections.
• This novel method offers improved specificity by reducing false positives associated with plant-derived glucans.
• The SSMC-based system represents a significant advancement in the accurate and reliable diagnosis of invasive fungal infections.