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Immunological characterization of Asp f 2, a major allergen from Aspergillus fumigatus associated with allergic bronchopulmonary aspergillosis.

ABSTRACT: The 37-kDa recombinant protein Asp f 2, encoding an allergen of Aspergillus fumigatus, was expressed in a prokaryotic expression system and immunologically evaluated for its functional and structural properties. The open reading frame for a 310-amino-acid-long protein was shown to encode a signal peptide of 31 amino acids. A native 37-kDa culture filtrate protein and a 55-kDa mycelial glycoprotein (gp55) exhibited complete N-terminal sequence homology to Asp f 2. A GenBank search for homologous proteins revealed 60 and 44% sequence homologies to the cytosolic protein ASPND1 from Aspergillus nidulans and fibrinogen binding protein from Candida albicans, respectively. The glycosylation sites and cysteine molecules are conserved in all the three proteins. The extracellular matrix protein laminin showed a dose-dependent interaction with Asp f 2. This protein, expressed as a major cell-associated protein within 24 h of in vitro fungal culture, comprises 20 to 40% of total fungal protein. Furthermore, both native and recombinant Asp f 2 exhibited specific immunoglobulin (IgE) binding with allergic bronchopulmonary aspergillosis (ABPA) and cystic fibrosis-ABPA patients, whereas A. fumigatus-sensitized allergic asthma and normal control subjects failed to show IgE binding with Asp f 2. These results indicate that Asp f 2 is a major allergen of A. fumigatus exhibiting IgE antibody binding with sera from patients with ABPA. The antigen should be explored further for its potential role in the differential diagnosis of A. fumigatus-associated allergic diseases.

SUBMITTER: Banerjee B

PROVIDER: S-EPMC108645 | biostudies-literature | 1998 Nov

REPOSITORIES: biostudies-literature

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Immunological characterization of Asp f 2, a major allergen from Aspergillus fumigatus associated with allergic bronchopulmonary aspergillosis.

Banerjee B B Greenberger P A PA Fink J N JN Kurup V P VP

Infection and immunity 19981101 11

The 37-kDa recombinant protein Asp f 2, encoding an allergen of Aspergillus fumigatus, was expressed in a prokaryotic expression system and immunologically evaluated for its functional and structural properties. The open reading frame for a 310-amino-acid-long protein was shown to encode a signal peptide of 31 amino acids. A native 37-kDa culture filtrate protein and a 55-kDa mycelial glycoprotein (gp55) exhibited complete N-terminal sequence homology to Asp f 2. A GenBank search for homologous ...[more]

PMID: 9784519

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Project description:A vaccine that effectively protects immunocompromised patients against invasive aspergillosis is a novel approach to a universally fatal disease. Here we present a rationale for selection and in vivo testing of potential protein vaccine candidates, based on the modification of an immunodominant fungal allergen for which we demonstrate immunoprotective properties. Pulmonary exposure to viable Aspergillus fumigatus conidia as well as vaccination with crude hyphal extracts protects corticosteroid-immunosuppressed mice against invasive aspergillosis (J. I. Ito and J. M. Lyons, J. Infect. Dis. 186:869-871, 2002). Sera from the latter animals contain antibodies with numerous and diverse antigen specificities, whereas sera from conidium-exposed mice contain antibodies predominantly against allergen Asp f 3 (and some against Asp f 1), as identified by mass spectrometry. Subcutaneous immunization with recombinant Asp f 3 (rAsp f 3) but not with Asp f 1 was protective. The lungs of Asp f 3-vaccinated survivors were free of hyphae and showed only a patchy low-density infiltrate of mononuclear cells. In contrast, the nonimmunized animals died with invasive hyphal elements and a compact peribronchial infiltrate of predominantly polymorphonuclear leukocytes. Three truncated versions of rAsp f 3, spanning amino acid residues 15 to 168 [rAsp f 3(15-168)], 1 to 142, and 15 to 142 and lacking the known bipartite sequence required for IgE binding, were also shown to be protective. Remarkably, vaccination with either rAsp f 3(1-142) or rAsp f 3(15-168) drastically diminished the production of antigen-specific antibodies compared to vaccination with the full-length rAsp f 3(1-168) or the double-truncated rAsp f 3(15-142) version. Our findings point to a possible mechanism in which Asp f 3 vaccination induces a cellular immune response that upon infection results in the activation of lymphocytes that in turn enhances and/or restores the function of corticosteroid-suppressed macrophages to clear fungal elements in the lungs.

Project description:BackgroundAllergic bronchopulmonary aspergillosis (ABPA) reflects hypersensitivity and an exaggerated immune response to Aspergillus fumigatus. ABPA typically occurs in individuals with airway diseases such as asthma or cystic fibrosis and is associated with worse outcomes for individuals with these conditions. Each year, physicians across the province of British Columbia submit over 2600 diagnostic testing requests to a centralized location in Vancouver, requiring specimen collection, storage, and shipment from different clinics across the province. Timely and reliable testing of Aspergillus precipitins is critical to optimizing diagnosis and management of ABPA. At our centre, we analyzed sample stability in varying storage conditions to provide guidance to those using this routine diagnostic test.MethodsTo determine temperature and time stability, 31 serum specimens positive for Aspergillus fumigatus precipitins from routine clinical testing were each aliquoted and incubated at 4 and 37 °C. Samples were repeatedly assayed for precipitins to Aspergillus fumigatus via agarose gel double immunodiffusion (AGID) at 7, 14, and 28 days post-incubation.To determine freeze-thaw stability, 39 serum specimens submitted for routine clinical testing for Aspergillus precipitins were randomly selected. Each specimen was aliquoted and stored at 4 or -20 °C. 4 °C samples were maintained at 4 °C while -20 °C samples were split into three groups corresponding to one, two, or three freeze-thaw cycles. -20 °C samples were thawed at room temperature in the morning and then immediately frozen overnight for up to a total of three freeze-thaw cycles.ResultsRegarding temperature and time stability, median stability time was 47 and 34 days at 4 and 37 °C, respectively. The log-rank model indicates no statistically significant difference between the two temperature storage conditions (p = 0.14) with a hazard ratio of 0.61 (95% CI, 0.31-1.2).In terms of freeze-thaw stability, no indication of serum degradation with regards to Aspergillus fumigatus precipitins was found with repeated freeze-thaw cycles as compared to refrigerated storage.ConclusionsThe stability of serum precipitins to Aspergillus fumigatus was found to be dependent on time, but not temperature and freeze-thaw cycles. Specimens for Aspergillus fumigatus precipitins testing should be shipped at ambient temperature and tested within 2 weeks from collection.

Dataset Information

Immunological characterization of Asp f 2, a major allergen from Aspergillus fumigatus associated with allergic bronchopulmonary aspergillosis.

Publications

Immunological characterization of Asp f 2, a major allergen from Aspergillus fumigatus associated with allergic bronchopulmonary aspergillosis.

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