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Scavenger receptor class B member 1 (SCARB1) variants modulate hepatitis C virus replication cycle and viral load
Sandra Westhaus1, Maximilian Deest2, Anna T X Nguyen2
1Department of Gastroenterology, Hepatology und Endocrinology, Hannover Medical School, Hannover, Germany; Institute of Virology, University Hospital Essen, Essen, Germany; German Center for Infection Research (DZIF), Hannover-Braunschweig Site, Germany.
Insights
Genetic variations in the SCARB1 gene impact hepatitis C virus (HCV) infection. Specific SCARB1 variants affect HCV replication and viral load, influencing disease course.
Area of Science:
- Genetics
- Virology
- Hepatology
Background:
- The scavenger receptor class B member 1 (SR-BI) is crucial for hepatitis C virus (HCV) entry into liver cells.
- Numerous genetic variants exist in the SCARB1 gene, but their precise effects on HCV infection are not fully understood.
Purpose of the Study:
- To investigate the impact of coding and non-coding SCARB1 variants on HCV replication and the clinical progression of hepatitis C.
- To elucidate the molecular mechanisms by which SCARB1 variants influence HCV infectivity and viral load.
Main Methods:
- Analysis of key coding non-synonymous and non-coding SCARB1 variants.
- Utilized in vitro virological assays and human genetics approaches to assess variant function.
- Haplotype analysis was performed to identify combined effects of variants.
Main Results:
- Non-synonymous variants S112F and T175A significantly impaired SR-BI's HCV receptor function by reducing interaction with HCV E2.
- The G allele of non-coding variant rs3782287 was associated with decreased viral load.
- Haplotype analysis revealed rs3782287 A/rs5888 C as a risk haplotype linked to increased viral load.
- A trend towards lower hepatic SR-BI expression was observed in individuals with the rs3782287 GG genotype.
Conclusions:
- Both coding and non-coding genetic variants in SCARB1 modulate the HCV replication cycle.
- These findings highlight SR-BI's role as a key HCV receptor and explain inter-individual variability in HCV infection.
- SCARB1 variants may influence the clinical features of hepatitis C.
Background & Aims:
There are numerous coding and non-coding variants in the SCARB1 gene that encodes scavenger receptor class B member 1 (SR-BI), a key receptor for both high density lipoproteins and hepatitis C virus (HCV). Many have been linked to clinical phenotypes, yet their impact on the HCV replication cycle is incompletely understood. The aim of this study was to analyze the impact of these variants on the molecular biology and clinical course of HCV.
Methods:
We analyzed key coding non-synonymous as well as non-coding SCARB1 variants using virological in vitro and human genetics approaches.
Results:
Non-synonymous variants: S112F and T175A have greatly reduced HCV receptor function. When present on the cell surface, these variants are impaired in their ability to interact with HCV E2. Non-coding variants: The G allele in rs3782287 is associated with decreased viral load. Haplotype analysis confirmed these findings and identified haplotype rs3782287 A/rs5888 C as a risk allele associated with increased viral load. We also detected a trend towards lower hepatic SR-BI expression in individuals with the rs3782287 GG genotype associated with low viral load suggesting a potential underlying mechanism.
Conclusion:
Coding and non-coding genetic SCARB1 variants modulate the HCV replication cycle and possibly clinical features of hepatitis C. These findings underscore the relevance of SR-BI as an HCV receptor and contribute to our understanding of inter-individual variation in HCV infection.
Lay Summary:
The cell surface receptor SR-BI (scavenger receptor class B member 1), is essential for hepatitis C virus (HCV) entry into hepatocytes. Variations in the gene coding this receptor influence infectivity and viral load. We analyzed these variations to gain a better understanding of inter-individual differences over the course of HCV infection.