lid-1 Antibody
Description
Introduction to LID-1 Antibody
The LID-1 antibody refers to immunoglobulins (primarily IgG1) that target the LID-1 antigen, a recombinant fusion protein used in diagnosing Mycobacterium leprae infections. LID-1 is part of the LID (Leprosy ID) panel, which combines antigens to improve serological detection of leprosy, particularly in multibacillary (MB) cases .
Mechanism of Action and Antigen Structure
LID-1 is a synthetic protein designed to mimic M. leprae epitopes. It is composed of:
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NDO: A synthetic peptide mimicking the phenolic glycolipid-I (PGL-I) component of M. leprae.
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LID-1: A fusion protein containing sequences from the M. leprae proteins ML0049 and ML0050 .
The LID-1 antibody response is dominated by IgG1 isotypes, which correlate with high bacillary loads and MB leprosy . Unlike IgM responses (e.g., to NDO-BSA), IgG1 against LID-1 is specific to M. leprae and distinguishes MB from paucibacillary (PB) leprosy .
Sensitivity and Specificity
LID-1 demonstrates high specificity but moderate sensitivity, particularly for MB leprosy:
| Parameter | LID-1 | NDO-BSA | NDO-LID |
|---|---|---|---|
| Sensitivity (MB) | 89% | 95% | 95% |
| Specificity (MB) | 96% | 88% | 88% |
| AUC (MB) | 0.963 | 0.961 | 0.978 |
Note: AUC = Area Under the Curve (ROC analysis). Higher AUC indicates better diagnostic accuracy.
Clinical Correlation
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Bacillary Load: Antibody levels strongly correlate with bacterial index (BI) in MB patients (r = 0.84 for LID-1; p < 0.001) .
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Disease Spectrum: LID-1 antibodies are absent in PB leprosy (TT/BT) and rise linearly from tuberculoid to lepromatous poles (TT → LL) .
NDO-BSA vs. LID-1 vs. NDO-LID
NDO-LID (a conjugate of NDO and LID-1) outperforms individual antigens in combined sensitivity and specificity:
| Group | LID-1 Sensitivity | NDO-BSA Sensitivity | NDO-LID Sensitivity |
|---|---|---|---|
| MB | 89% | 95% | 95% |
| PB | 0% | 7% | 17% |
| Household Contacts (HHC) | 11.9% | 17.8% | N/A |
Longitudinal Studies
Serum LID-1 antibody levels predict leprosy progression in high-risk groups:
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Household Contacts (HHC):
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Risk Estimation: A linear model predicts 8.3% of HHC with LID-1 seropositivity will develop leprosy .
Challenges and Limitations
Product Specs
Constituents: 50% Glycerol, 0.01M PBS, pH 7.4
Target Background
- In the intestinal cells of *C. elegans*, a newly identified protein, lipid droplet protein 1 (LID-1; C25A1.12), modulates lipolysis by binding to adipose triglyceride lipase 1 (ATGL-1; C05D11.7) during periods of nutritional deprivation. PMID: 25202121
