Host factor interactions during early steps of Hepatitis C Virus cell entry and their inter-individual modulation by genetic and pharmacological perturbations
Red-fluorescent sensor that detects HCV infection of cultivated liver cells. In uninfected cells (upper panel) all signal is in the cytoplasm. In an infected culture (lower panel) the signal has moved to the nucleus in most cells – these are infected by HCV.
The hepatitis C virus causes a chronic infection of the liver, which in the long run can lead to scarring of the liver (liver cirrhosis), liver failure and liver cancer. Approximately 71 million people worldwide are chronically infected with hepatitis C. The disease is known to cause liver cancer. Although hepatitis C is curable today, many people, especially in underprivileged countries, are unaware of their infection and have no access to treatment. Unfortunately, a preventive vaccine is not yet available.
Clinically it has been shown that there are individual differences in the course of hepatitis C infection. An estimated 70 to 75% of those exposed develop a chronic infection. Of these, about 30% must expect the development of liver damage after 15 to 20 years without therapeutic intervention. Why people react differently to a hepatitis C infection is currently poorly understood.
The research groups led by Gisa Gerold and Thomas von Hahn are investigating how inter-individual differences influence hepatitis C infection. Their main focus is on genetic variations in humans and treatment with lipid-reducing drugs. The latter is based on the fact that the virus interacts strongly with the human lipid metabolism. The researchers look at how the virus penetrates liver cells and then multiplies. When entering liver cells, the virus uses several human proteins that form a complex on liver cells and play a central role in human fat metabolism. Gisa Gerold’s and Thomas von Hahn’s teams are investigating how this complex, i.e. the entry portal of the virus, is altered by genetic variants and pharmacological intervention in the lipid metabolism, which ultimately influences virus proliferation and the progression of chronic hepatitis C. They hope to gain new insights into the function of the hepatitis C virus, new diagnostic possibilities and, in the long term, new therapeutic approaches.
The HCV replication cycle and the clinical course of hepatitis C are modulated by genetic and non-genetic variation in the host. CD81, CAPN5, CBLB and SR-BI – the latter a physiological hepatic receptor for lipoproteins – are important host factors for HCV and essential for cell entry of the virus. Numerous genetic variants exist in the genes encoding these five factors. Many of them have a clinical phenotype, mostly in the form of an altered serum lipid profile. However, the effects of these variants on chronic HCV infection are unknown. Moreover, the extent to which drugs that influence lipid metabolism modulate HCV infection remains enigmatic. This project aims to clarify how variation in HCV entry factors and non-genetic factors, such as lipid-reducing drugs, affect the HCV replication cycle and the ability of the virus to establish and maintain a chronic infection.
The project has four parts:
- Known coding non-synonymous CD81, SR-BI variants are expressed in cell lines in which expression of the endogenous factor has been knocked out. We then measure the ability of the variants to serve as HCV receptors using HCV reporter viruses and pseudoparticles.
- Selected CD81 variants are tested to determine whether they affect interaction with SR-BI, CAPN5 and CBLB and how an altered interaction modulates HCV cell entry.
In a complementary approach, we investigate the effects of clinically used lipid-lowering drugs on HCV infection. In particular, we will analyze the expression levels of SR-BI, LDLr and CD81, the membrane and cell cholesterol content and the HCV infection of hepatocytes in vitro and in vivo in the presence of the drugs. Finally, we investigate viral load and hepatitis in patients with chronic hepatitis C under statin therapy.
- Genetic variants of the CD81 interaction partners CBLB and CAPN5 are tested to determine whether they modulate HCV susceptibility. We then characterize selected variants with respect to their interaction with CD81 and SR-BI. For the characterization of multi-protein complexes we use high-resolution quantitative proteomics.
Representation of the gene structure of SCARB1. Genetic variants of interest are indicated.
Gisa Gerold is talking about her research at CRC 900
Gisa Gerold jointed the project at the start of the third funding period in 2018. Together with Thomas von Hahn she is jointly leading the project C7, which addresses the influence of different gene variants and the pharmacological intervention in lipid metabolism on the course of infection with hepatitis C virus.
Thomas von Hahn is talking about his research at CRC 900
Thomas von Hahn joined the CRC at the start of the second funding period in 2014. Together with Gisa Gerold he is jointly leading the project C7, which addresses how various variants of a gene with a central role in fat metabolism influence the course of infection with hepatitis C virus.
Publications of the project C7
- Hepatitis C virus enters liver cells using the CD81 receptor complex proteins calpain-5 and CBLB. Bruening J, Lasswitz L, Banse P, Kahl S, Marinach C, Vondran FW, Kaderali L, Silvie O, Pietschmann T, Meissner F, Gerold G. Plos Pathog. 2018 Juli;14(7):e1007111.
- CD81 Receptor Regions outside the Large Extracellular Loop Determine Hepatitis C Virus Entry into Hepatoma Cells. Banse P, Moeller R, Bruening J, Lasswitz L, Kahl S, Khan AG, Marcotrigiano J, Pietschmann T, Gerold G. Viruses 2018 Apr;10(4).
A screening assay for the identification of host cell requirements and antiviral targets for hepatitis D virus infection. Buchmann B, Döhner K, Schirdewahn T, Sodeik B, Manns MP, Wedemeyer H, Ciesek S, von Hahn T. Antiviral Res. 2017 May;141:116-123.
Scavenger receptor class B member 1 (SCARB1) variants modulate hepatitis C virus replication cycle and viral load. Westhaus S, Deest M, Nguyen ATX, Stanke F, Heckl D, Costa R, Schambach A, Manns MP, Berg T, Vondran FWR, Sarrazin C, Ciesek S, von Hahn T. J Hepatol. 2017 Mar 29. pii: S0168-8278(17)30184-8.
Cyclophilin polymorphism and virus infection. von Hahn T, Ciesek S. Curr Opin Virol. 2015 Oct;14:47-9. Review.
- Quantitative Proteomics Identifies Serum Response Factor Binding Protein 1 as a Host Factor for Hepatitis C Virus Entry. Gerold G, Meissner F, Bruening J, Welsch K, Perin PM, Baumert TF, Vondran FW, Kaderali L, Marcotrigiano J, Khan AG, Mann M, Rice CM, Pietschmann T. Cell Rep. 2015 Aug;12(5):864-78.
Primary biliary acids inhibit hepatitis D virus (HDV) entry into human hepatoma cells expressing the sodium-taurocholate cotransporting polypeptide (NTCP). Veloso Alves Pereira I, Buchmann B, Sandmann L, Sprinzl K, Schlaphoff V, Döhner K, Vondran F, Sarrazin C, Manns MP, Pinto Marques Souza de Oliveira C, Sodeik B, Ciesek S, von Hahn T. PLoS One. 2015 Feb 3;10(2):e0117152.
Impact of single nucleotide polymorphisms in the essential HCV entry factor CD81 on HCV infectivity and neutralization. Deest M, Westhaus S, Steinmann E, Manns MP, von Hahn T, Ciesek S. Antiviral Res. 2014 Jan;101:37-44.
Characterization of the inhibition of hepatitis C virus entry by in vitro-generated and patient-derived oxidized low-density lipoprotein. Westhaus S, Bankwitz D, Ernst S, Rohrmann K, Wappler I, Agné C, Luchtefeld M, Schieffer B, Sarrazin C, Manns MP, Pietschmann T, Ciesek S, von Hahn T. Hepatology. 2013 May;57(5):1716-24.