Reinvestigation of carbohydrate specificity of EB-A2 monoclonal antibody used in the immune detection of Aspergillus fumigatus galactomannan

Great progresses have been made in the recent years in the detection of circulating galactofuranose-bearing molecules for the diagnosis of aspergillosis. However, the test used in the clinical practice is hampered by the occurrence of false positives. A glycoarray with dozens of oligosaccharides structurally related to the Aspergillus fumigatus galactomannan has allowed us to reinvestigate the carbohydrate specificity of the EB-A2 monoclonal antibody used in the Platelia (TM) Aspergillus sandwich immune assay. We have now demonstrated that the mAb can recognize shorter oligosaccharides than the previously reported tetrasaccharide Galf-beta-(1 -> 5)-Galf-beta-(1 -> 5)-Galf-beta-(1 -> 5)-Galf-beta and oligosaccharides which contains alternating beta-(1 -> 5)/beta-(1 -> 6)-linkages. This result could explain the occurrence of false-positive signals due to the presence of the abovementioned epitopes not only in A. fumigatus galactomannan but also in other bacteria and fungi.