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Evaluating the Potential of Galactosaminogalactan as a Diagnostic Target for Invasive Aspergillosis

Summary

Researchers developed a new test to detect invasive fungal infections caused by Aspergillus by targeting a molecule called galactosaminogalactan (GAG) on the fungus surface. The test worked very well in mice with the infection and showed better specificity than current methods. However, the test did not detect GAG in blood or other body fluids from human patients, suggesting that additional research is needed before it can be used clinically.

Background

Invasive aspergillosis (IA) is a serious opportunistic infection affecting immunocompromised patients, with an estimated 2 million deaths annually worldwide. Current diagnostic methods using galactomannan (GM) detection have limitations in sensitivity and specificity. Galactosaminogalactan (GAG), a polysaccharide component of Aspergillus cell walls, represents a potential alternative diagnostic marker.

Objective

To evaluate the diagnostic utility of GAG as a biomarker for invasive aspergillosis by developing a monoclonal antibody-based ELISA, assessing its specificity across various pathogens, and comparing its performance with GM detection in both mouse models and human clinical samples.

Results

The GAG ELISA showed strong reactivity with Aspergillus fumigatus and Aspergillus flavus with minimal cross-reactivity to other pathogens. In mice with IA, GAG was detected in lung tissue, serum, BALF, and urine with strong correlation to fungal burden. However, GAG was not detectable in human serum, BALF, or urine samples despite being visible in human lung tissue immunostaining.

Conclusion

While GAG ELISA shows promise as a diagnostic tool in experimental models and demonstrates higher specificity than GM, the failure to detect GAG in human body fluids requires further investigation. Additional research is needed to understand whether GAG levels are insufficient in natural human infection or if host factors interfere with detection.
  • Published in:Mycoses,
  • Study Type:Experimental Study,
  • Source: PMID: 41060078, DOI: 10.1111/myc.70125
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