Related Experiment Videos
Serodiagnosis of tuberculosis using the A60 IgG ELISA
1Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, R.O.C.
Insights
This study evaluated enzyme-linked immunosorbent assay (ELISA) for tuberculosis (TB) serodiagnosis using IgG against mycobacterial antigen 60 (A60). The test showed promise, particularly in high TB prevalence areas, with positive results supporting active TB diagnosis.
Area of Science:
- Immunology
- Infectious Diseases
- Medical Diagnostics
Background:
- Tuberculosis (TB) diagnosis remains a challenge, especially in resource-limited settings.
- Serodiagnostic tests offer a potential alternative or adjunct to traditional diagnostic methods.
- Evaluating novel biomarkers like mycobacterial antigen 60 (A60) is crucial for improving TB detection.
Purpose of the Study:
- To evaluate the efficacy of an enzyme-linked immunosorbent assay (ELISA) for detecting IgG antibodies against mycobacterial antigen 60 (A60) for tuberculosis serodiagnosis.
- To determine the sensitivity and specificity of the A60 IgG ELISA in patients with active TB, old pulmonary TB, and various control groups.
- To assess the diagnostic utility of the A60 IgG ELISA in different TB prevalence scenarios.
Main Methods:
- An enzyme-linked immunosorbent assay (ELISA) was developed to detect IgG antibodies against mycobacterial antigen 60 (A60).
- The study included 63 patients with TB (50 active, 13 old) and 43 controls (healthy, non-TB pulmonary, non-pulmonary infectious diseases).
- A cut-off value of 200 units was used to classify samples as positive or negative.
Main Results:
- The A60 IgG ELISA demonstrated a low false-positive rate (5%) in control groups.
- Serological positivity in active TB cases varied: 82% (smear-positive), 67% (smear-negative/culture-positive), and 38% (culture-negative).
- A positive IgG ELISA result may support the diagnosis of active TB, especially in populations with high TB prevalence.
Conclusions:
- The A60 IgG ELISA shows potential as a valuable tool for TB serodiagnosis.
- The test's predictive values are influenced by TB prevalence, making it more informative in high-prevalence settings.
- Further validation is warranted to establish its role in clinical TB diagnostics.
Abstract:
The serodiagnosis of tuberculosis (TB) by using an enzyme-linked immunosorbent assay (ELISA) to detect IgG against mycobacterial antigen 60 (A60) was evaluated. Forty-three controls (10 healthy adults, 19 patients with non-tuberculous pulmonary diseases and 14 patients with non-pulmonary infectious diseases) and 63 patients with TB in different disease activity (50 patients with active TB and 13 patients with old pulmonary TB) were studied. When a cut-off value of 200 units was selected, the results obtained with controls were: 100% negative in IgG titers in healthy adults and patients with non-pulmonary infectious diseases, 89% negative in IgG titers in patients with non-tuberculous pulmonary diseases. The overall "false positive" rate was 5% in the control groups. The percentage of serologically positive cases of active TB was: 82% in smear-positive, 67% in smear-negative/culture-positive and 38% in culture-negative. Of the 13 patients with calcified pulmonary TB, four had a positive serological response (31%). Four out of eight patients with active TB showed an elevation in IgG titer 1 to 3 months after diagnosis and anti-TB chemotherapy. The positive and negative predictive values of the test may provide valuable information according to the prevalence of TB in different populations. When the TB prevalence is high, a positive IgG ELISA test may support the diagnosis of active TB.