Potential of fluorescence polarization immunoassay for the detection of Aspergillus fumigatus galactomannan

Abstract

Galactomannan (GM) is a specific polysaccharide antigen of opportunistic mold fungi of the genus Aspergillus. The detection of GM in patients’ biological fluids is a reliable criterion for the diagnosis of invasive pulmonary aspergillosis, a severe disease. In this report, we evaluated the analytical capabilities of the fluorescence polarization immunoassay (FPIA) for detection of GM. Using FPIA, the high affinity of the monoclonal antibody 7B8 to the synthetic oligosaccharide β-d-Galf-[(1→5)-β-d-Galf]₃-(1→6)-α-d-Manp related to the galactomannan fragment was shown. The binding constant in this interaction was found to be equal to (1.02±0.01) • 10⁸ L mol^-1. The detection limit determined for this oligosaccharide with the competitive FPIA method is 3 ng mL^-1. The data obtained indicate the possibility of using FPIA for the diagnosis of invasive aspergillosis.