Analysis of HIV seropositive thalassemic children for antibodies specific to Aspergillus fumigatus by luminescent immunoassay

Antibody testing in aspergillosis--quo vadis?

Humans are constantly exposed to airborne Aspergillus spores. Most develop Aspergillus-specific antibodies by adulthood. Persons with chronic lung disease or Aspergillus airway colonization often have raised levels of Aspergillus-specific immunoglobululin G (IgG). It is not known whether this signifies an increased risk of future aspergillosis.Chronic and allergic forms of pulmonary aspergillosis are estimated to affect over three million people worldwide. Antibody testing is central to diagnosis of these conditions, with raised Aspergillus-specific IgG in chronic pulmonary aspergillosis and raised Aspergillus-specific IgE in allergic aspergillosis. Antibody levels are also used to monitor treatment response in these syndromes. Acute invasive disease is less common. There is a more limited role for antibody testing in this setting as immunosuppression often results in delayed or absent antibody response.Many methods exist to detect Aspergillus-specific antibodies, but there are limited published data regarding comparative efficacy and reproducibility. We discuss the comparative merits of the available tests in the various clinical settings and their suitability for use in the resource-poor settings where the majority of cases of aspergillosis are thought to occur. We summarize the gaps in existing knowledge and opportunities for further study that could allow optimal use of antibody testing in this field.

Elisa based diagnostic test for Aspergillosis

Detection of lgE and lgG antibodies in Aspergillosis is of diagnostic significance. The serological methods, such as agglutination, gel diffusion and counter immuno electrophoresis that are commonly used in the laboratories for diagnosis of Aspergillus induced infections, are less sensitive and high cross reactivity is often encountered. We carried out work on characterization and identification of diagnostically relevant antigens ofA. fumigatus. Well characterized antigens were used to develop an ELISA with 92% sensitivity and 89% specificity for detection of specific lgE and lgG in the sera of patients of allergic bronchopulmonary aspergillosis (ABPA), aspergilloma and invasive aspergillosis. Subsequently, a sample kit having "ready to use type" of dry reagents (powder/tableted buffers and lyophilized antigen, conjugate and reference sera) was formulated. The kit was validated with sera from patients of ABPA, related allergic disorders, tuberculosis, post-Kochs cases and thalassemic children receiving repeated blood transfusions. The performance of the kit was found to be satisfactory with coded sera.

Novel cytosolic allergens of Aspergillus fumigatus identified from germinating conidia

Aspergillus fumigatus is the common cause of allergic broncho-pulmonary aspergillosis (ABPA) and most of the allergens have been described from its secreted fraction. In the present investigation, germinating conidial cytosolic proteins of A. fumigatus were extracted from a 16 h culture. The proteome from this fraction was developed, and immuno-blots were generated using pooled ABPA patients' sera. Well separated Immunoglobulin-E (IgE) and Immunoglobulin-G (IgG) reactive spots were picked from corresponding 2DE gels and subjected to mass spectrometric analysis. As a result, 66 immuno-reactive proteins were identified from two geographically different strains (190/96 and DAYA) of A. fumigatus. Only 3 out of 66 proteins reacted with IgG, and the remaining 63 proteins were found to be IgE reactive. These 63 IgE-reactive cytosolic proteins from germinating conidia included 2 already known (Asp f12 and Asp f22) and 4 predicted allergens (Hsp88, Hsp70, malate dehydrogenase, and alcohol dehydrogenase) based on their homology with other known fungal allergens. In view of this, the panel of presently identified IgE-reactive novel proteins holds the potential of providing a basis for the wider diagnostic application in assay for allergic aspergillosis. We could demonstrate that recombinantly expressed proteins from this panel showed consistent reactivity with IgE of individual sera of ABPA patients. The recombinantly expressed proteins may also be useful in desensitization therapy of allergic disorders including ABPA.

Studies on antimycotic properties of Datura metel

The hexane, chloroform, acetone and methanolic fractions of Datura metel L. were investigated for antifungal properties using pathogenic species of Aspergillus. The chloroform fraction was found to be endowed with antifungal activity. The minimum inhibitory concentration (MIC) of chloroform fraction of D. metel L. was 625.0 microg ml(-1) against all the three species of Aspergillus, i.e. A. fumigatus, A. flavus and A. niger, by microbroth dilution and percent spore germination inhibition assays. The MIC by disc diffusion assay was observed to be 12.5 microg disc(-1). The chloroform fraction of D. metel, when investigated for potency, turned to be 9.2 times less active than amphotericin B. However, it was important to note that the cytotoxicity of chloroform fraction in vitro was 117.8 times less than amphotericin B.