Aspergillus fumigatus somatic antigens: comparison between two methods of preparation and immunochemical characterization

Abstract

Aspergillus fumigatus and other species of the same genus can cause different pathological processes amongst which can be found pulmonary hypersensitivity, intracavitary colonization and invasive and disseminated aspergillosis. The diagnosis of these processes is helped in a great way by the immunological response of the patient to Aspergillus antigens or by the detection of these as a metabolic product in blood and other fluids such as urine. To date, no firm agreement exists regarding the best preparation and standardization technique of aspergillar antigens, which is however the most important step towards the development of immunological diagnostic tests. In this study, two methods for the obtention of A. fumigatus somatic antigens have been compared, using 3 strains of different origins. The main differences between both antigenic extraction methods were the liquid media used for cultures (Czapek and Glucose peptone), the incubation times (4 weeks and 3 days respectively), the type of agitation during the incubation period (intermittent or continuous) and the dialysis and concentration method. The antigens obtained were standardized by the determination of the proteic and hydrocarbonate content, vertical electrophoresis in SDS PAGE, immunoprecipitation and immunoblotting against experimental antisera. From the comparison between both extraction methods, it was found that the highest proteic content was obtained with the somatic antigens of mycelium developed in Czapek for 4 weeks, whereas fungi cultivated in Glucose peptone had a higher glucide content. Vertical electrophoresis revealed the presence of 6 common fractions in all the antigens, whilst some fractions were in majority, only found in one antigen such as the MW 109 kDa, present in the GP 69 antigen.(ABSTRACT TRUNCATED AT 250 WORDS)