EXPRESSION OF THE CU,ZN SUPEROXIDE-DISMUTASE OF ASPERGILLUS-FUMIGATUSAS DETERMINED BY IMMUNOCHEMISTRY AND IMMUNOELECTRON MICROSCOPY

A polyclonal antibody against purified Cu,Zn superoxide dismutase (SOD ) from the pathogen Aspergillus fumigatus was raised in a sheep. This antibody recognised purified A. fumigatus SOD, together with a single band of 19 kDa in A. fumigatus cytoplasmic antigen, by immunodevelopme nt of western blots. The polyclonal serum did not recognise either the manganese or iron containing forms of the enzyme; however, it was rea ctive against putative Cu,Zn SODs in other members of the genus Asperg illus. Immunofluorescent staining of A. fumigatus cultures demonstrate d expression of the Cu,Zn SOD in conidia and hyphae, with the cell wal l staining particularly intensely. Conidiophores were stained in an un iformly intense pattern. Immunoelectron microscopy confirmed that the SOD was present within the hyphal cell wall, although there was also l abelling in the cytoplasm. SOD may protect Aspergillus against oxidant s produced by immune effector cells and these observations demonstrate that the enzyme is available to perform its antioxidant function with in the cell wall.