An immunodominant 90-kilodalton Aspergillus fumigatus antigen is the subunit of a catalase

Abstract

We have identified, purified, and characterized structurally and functionally a 90-kDa immunodominant antigen associated with the water- soluble fraction of Aspergillus fumigatus. This antigen is recognized by 90.3% of serum samples from patients with aspergilloma and should be considered either by itself or better in combination with other purified antigens as a candidate or developing a standardized immunoassay for the detection of aspergilloma. p90 is a glycoprotein containing at least two N- linked sugar chains of 2 and 5 kDa, respectively, which are not necessary for its reactivity, with aspergilloma serum samples. Using specific anti-p90 rabbit serum, we have demonstrated that under native conditions, p90 exists in oligomeric form and has associated catalase activity. This activity is resistant to extreme temperatures (>60°C), reducing agents (40 mM dithiothreitol), high concentrations of denaturing agents such as 8 M urea and 8% sodium dodecyl sulfate, and treatments with ethanol-chloroform-water (5:3:10 [vol/vol]) mixtures.