HCV NS3 (1192-1459 a.a.)
Description
Introduction to HCV NS3 (1192–1459 aa)
HCV NS3 (aa 1192–1459) refers to the helicase domain of the nonstructural protein 3 (NS3) in hepatitis C virus (HCV). This region is critical for viral replication, as it facilitates RNA unwinding via ATP-dependent helicase activity and nucleic acid binding . The helicase domain is structurally distinct from the N-terminal protease domain (aa 1–180) and is essential for processing viral RNA and interacting with host factors . Recombinant versions of this region (e.g., GST-fused proteins produced in E. coli) are widely used in research for antibody production, diagnostic assays, and structural studies .
Domain Organization and Key Features
The HCV NS3 helicase (aa 1192–1459) includes:
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ATP-binding motifs: Walker A (K210) and Walker B motifs critical for ATP hydrolysis .
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Nucleic acid-binding regions: Motifs I, II, and III involved in RNA-DNA interactions .
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Conserved epitopes: Linear (e.g., EP05: 1231PTGSGKSTK) and semi-conformational sequences recognized by monoclonal antibodies (mAbs) .
Antibody Responses and Epitope Mapping
The NS3 helicase domain elicits strong humoral immune responses, particularly in chronic HCV infection:
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Dominant epitopes: EP05 (100% conserved) and EP21 (highly conserved) react with 59–79% of chronic HCV sera .
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Diagnostic utility: NS3#201 (aa 1192–1459) is used in serological assays to distinguish acute from chronic infections .
| Antigen | Acute HCV IgG Response (Geometric Mean) | Chronic HCV IgG Response (Geometric Mean) | Reference |
|---|---|---|---|
| NS3#201 | 0.87 | 6.82 | |
| Core | 3.74 | 13.10 |
Functional Inhibition and Viral Replication
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Helicase inhibition: mAb 2E12 (targeting EP05) reduces unwinding activity by 50% in vitro, highlighting its potential as an antiviral agent .
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Host-virus interactions: NS3 helicase may impair DNA repair via interactions with WRN (Werner syndrome) protein, exacerbating cellular damage .
Therapeutic and Prophylactic Applications
Product Specs
Product Science Overview
Hepatitis C Virus (HCV) is a significant global health concern, affecting millions of individuals worldwide. The virus is known for its ability to cause chronic liver diseases, including cirrhosis and hepatocellular carcinoma. Among the various genotypes of HCV, genotype 1b is one of the most prevalent and studied. The nonstructural protein 3 (NS3) of HCV plays a crucial role in the virus’s life cycle and is a target for antiviral therapies.
The NS3 protein is a multifunctional enzyme that contains three catalytic activities: serine protease, helicase, and nucleotide triphosphatase (NTPase). The N-terminal domain of NS3 exhibits protease activity, which is essential for the cleavage of the HCV polyprotein into functional units. The C-terminal domain contains helicase and NTPase activities, which are vital for the unwinding of RNA and the hydrolysis of nucleotides, respectively .
Research has identified several immunogenic regions within the NS3 protein. These regions are recognized by the immune system and can elicit an immune response in HCV-infected individuals. Four putative immunogenic regions have been identified: E (around amino acids 1250/1251), A (within amino acids 1250-1334), A/B (around amino acids 1323 and 1334), and B/C (around amino acids 1407 and 1412). Among these, region E is the most immunodominant .
The recombinant NS3 protein from HCV genotype 1b, covering amino acids 1192-1459, includes the full-length immunodominant region c33c. This recombinant protein is immunoreactive with sera from HCV-infected individuals, making it suitable for use in diagnostic assays such as ELISA and Western Blot . The recombinant protein is typically expressed in Escherichia coli and purified using chromatographic techniques .
The recombinant NS3 protein is used in various research and diagnostic applications. It is particularly useful in the detection of HCV infections due to its high specificity and minimal cross-reactivity. For storage, the protein can be kept at 4°C for short-term use or at -20°C for long-term storage. Aliquots are stable for at least six months when stored at -20°C .
