A new glycoprotein allergen/antigen with the protease activity from Aspergillus fumigatus.
BACKGROUND
Aspergillus fumigatus is an opportunistic fungus causing allergic and invasive aspergillosis in humans and animals. It secretes an array of complex biologically active glycoprotein antigens and allergens. It is important to identify and characterize probable potential virulent factors playing a major role in the pathogenesis of aspergillosis.


METHODS
Using protein purification techniques (lectin affinity chromatography, gel filtration, electroelution and high-pressure liquid chromatography), a major antigen/allergen with a molecular weight of 56 kD (gp56) from A. fumigatus was purified to homogeneity. The protein was characterized by immunoblot, ELISA and protease assays. The N-terminal amino acid sequencing was performed.


RESULTS
The gp56 protein showed a single band on silver staining and isoelectric focussing. The protein to carbohydrate ratio was 1.5:1 and gp56 gave a protein band at a molecular weight of 34 kD on enzymatic deglycosylation. It also exhibited IgG and IgE immunobinding with antibodies present in sera of allergic bronchopulmonary aspergillosis patients. The gp56 exhibited protease activity and N-terminal seven-amino acid sequence showed homology with fungal serine proteases.


CONCLUSIONS
The gp56 protein by virtue of its proteolytic activity could be one of the virulent factors of A. fumigatus involved in establishing infection in the host along with other factors.
Nigam
Shailly
S
Molecular Biochemistry and Diagnostics Division, Centre for Biochemical Technology, Delhi, India.
Ghosh
P C
PC
Sarma
P Usha
PU
D000485:Allergens / Q000276:immunology* / Q000302:isolation & purification; D000908:Antibodies, Fungal / Q000276:immunology; D000946:Antigens, Fungal / Q000276:immunology* / Q000302:isolation & purification; D001229:Aspergillosis, Allergic Bronchopulmonary / Q000276:immunology; D001232:Aspergillus fumigatus / Q000201:enzymology / Q000276:immunology*; D015153:Blotting, Western; D002241:Carbohydrates / Q000032:analysis; D002847:Chromatography, Agarose; D015180:Electrophoresis, Gel, Two-Dimensional; D010450:Endopeptidases / Q000276:immunology* / Q000302:isolation & purification; D004797:Enzyme-Linked Immunosorbent Assay; D006023:Glycoproteins / Q000276:immunology / Q000302:isolation & purification; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D010504:Periodic Acid / Q000378:metabolism
D000485:Allergens; D000908:Antibodies, Fungal; D000946:Antigens, Fungal; D002241:Carbohydrates; D006023:Glycoproteins; D007074:Immunoglobulin G; D010504:Periodic Acid; D007073:Immunoglobulin E; C009288:metaperiodate; D010450:Endopeptidases