Related Experiment Videos
Immunodiagnosis of nocardiosis
Insights
Researchers identified a specific 54-kDa antigen from Nocardia asteroides, crucial for diagnosing nocardiosis. This antigen shows promise for developing a sensitive and specific diagnostic test for this infection.
Area of Science:
- Medical Microbiology
- Immunology
- Diagnostic Development
Background:
- Nocardia asteroides causes nocardiosis, an infection often difficult to diagnose.
- Identifying specific antigens is key to developing accurate diagnostic tools.
Purpose of the Study:
- To purify and characterize immunodominant antigens of Nocardia asteroides.
- To develop specific diagnostic markers for nocardiosis.
Main Methods:
- Immunoaffinity chromatography was used to purify antigens from Nocardia asteroides culture filtrate.
- Western blot (immunoblot) analysis was performed using patient sera.
- Monoclonal antibodies (mAbs) were generated against the purified 54-kDa antigen.
Main Results:
- A 54-kDa antigen was purified and found to be immunodominant in patients with nocardiosis.
- The 54-kDa antigen showed specificity, with no cross-reactivity with sera from tuberculosis, leprosy, or healthy controls.
- Generated monoclonal antibodies reacted specifically with the 54-kDa antigen and showed no cross-reactivity with mycobacterial antigens.
Conclusions:
- The 54-kDa antigen is a specific marker for Nocardia asteroides infections.
- The developed monoclonal antibodies are suitable candidates for a sensitive and specific diagnostic test for nocardiosis.
Abstract:
A specific immunodominant 54-kDa antigen was purified from a culture filtrate of Nocardia asteroides by immunoaffinity chromatography. The chromatography column was prepared with immunoglobulin G obtained from sera from patients with lepromatous leprosy. Unbound solutes consisted of specific, partially purified N. asteroides antigens, primarily a 54-kDa band, accompanied by two others of 31 and 62 kDa. The Western blot (immunoblot) technique was applied to detecting the immunologic response to nocardiae in the serum of nocardiosis patients. Each of the serum samples from immunosuppressed or immunocompetent patients infected with N. asteroides reacted with the 54-kDa band, and two reacted with the 31- and 62-kDa bands. There was no reaction to either the 54- or the 31-kDa antigen with all serum samples obtained from patients with tuberculosis, except for one, with all serum samples obtained from patients with leprosy, or with all sera obtained from healthy controls. The partially purified 54-kDa antigen, specific for N. asteroides, was used as the immunogen to generate monoclonal antibodies (mAbs) and two mAbs were selected. As determined by Western blot, both mAbs reacted with the 54-kDa band. Using indirect immunofluorescence or enzyme immunoassay with whole N. asteroides micro-organisms, the mAbs did not react with N. asteroides cells. No cross-reactivity with mycobacterial antigens, either culture-filtrate antigens or tuberculin, was exhibited with any of the two mAbs. These mAbs are candidates to be used for the development of a sensitive and specific diagnostic test for nocardiosis.