HTLV-1 gp21
Description
Membrane Fusion Mechanism
HTLV-1 gp21 mediates fusion through a multi-step process:
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Receptor binding: Surface subunit gp46 interacts with heparan sulfate proteoglycans (HSPG) and neuropilin-1 (NRP-1) .
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Conformational change: Exposure of the FP enables insertion into the host membrane .
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Fusion activation: Interaction with glucose transporter-1 (GLUT-1) triggers fusion pore formation .
Immunosuppressive Properties
The FP region (residues 338–425) suppresses T-cell activation via:
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Th1/Th2 modulation: Reduces IFN-γ (Th1) and elevates IL-4 (Th2) cytokines .
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TCR bypass: Inhibits T-cell receptor signaling downstream of CD3ζ phosphorylation .
In vivo effects:
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Delayed onset of experimental autoimmune encephalomyelitis (EAE) in mice .
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Reduced CD4+ T-cell proliferation by 60–70% in human models .
Diagnostic Applications
HTLV-1 gp21 is a key antigen in serological assays. Performance metrics from recent studies :
| Assay Name | Method | Sensitivity (95% CI) | Specificity (95% CI) |
|---|---|---|---|
| Serodia HTLV-I | PA | 100% (92.44–100) | 100% (91.24–100) |
| Architect HTLV-I/II Score | CLIA | 99.19% (97.64–99.78) | 99.40% (98.70–99.72) |
| Espline HTLV-I/II | LFIA | 98.5% | 99.8% |
LFIA = Lateral flow immunoassay; CLIA = Chemiluminescent immunoassay.
Vaccine Development Prospects
HTLV-1 gp21 is a candidate for prophylactic vaccines due to:
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High conservation: <8% amino acid variability across isolates .
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Immunodominant epitopes: Residues 351–404 induce neutralizing antibodies .
Preclinical results:
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Recombinant gp21 vaccines elicited syncytium-inhibiting antibodies in rabbits .
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Murine models showed enhanced CD8+ T-cell responses to co-administered antigens .
Research Gaps and Future Directions
Product Specs
Product Science Overview
Human T-cell leukemia virus type 1 (HTLV-1) is a retrovirus that primarily infects T-lymphocytes, leading to diseases such as adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The virus is composed of several proteins, among which the envelope glycoprotein gp21 plays a crucial role in the virus’s ability to infect host cells.
The gp21 protein is a transmembrane glycoprotein that is part of the envelope complex of HTLV-1. It is derived from the precursor glycoprotein gp61, which is cleaved to form the surface glycoprotein gp46 and the transmembrane glycoprotein gp21 . The gp21 protein is essential for the fusion of the viral membrane with the host cell membrane, facilitating the entry of the viral RNA into the host cell .
Recombinant gp21 is a laboratory-produced version of the gp21 protein. It is typically expressed in bacterial systems such as E. coli and purified using chromatographic techniques . The recombinant form retains the immunodominant regions of the native protein, making it useful for various research and diagnostic applications.
- Diagnostic Tool: Recombinant gp21 is used as an antigen in enzyme-linked immunosorbent assays (ELISA) and Western blots to detect HTLV-1 infections. Its high specificity and minimal cross-reactivity make it an excellent reagent for accurate diagnosis .
- Research: The protein is used in studies to understand the mechanisms of HTLV-1 infection and the immune response to the virus. It helps in the development of vaccines and therapeutic strategies against HTLV-1 .
- Therapeutic Potential: Research has shown that the gp21 fusion peptide can inhibit antigen-specific T-cell activation, suggesting potential therapeutic applications in modulating immune responses .
